超好的环氧树脂复合材料英文文献

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高性能复合材料用环氧树脂胶黏剂的制备与性能_陈泽明

2.6 PSi/PMMA 改性氧树脂固化物 TEM 谱图分析由图 2.3 中的 DMA 测试可以看出增韧剂与环
氧树脂呈均相结构，通过增韧剂改性氧树脂固化物 TEM 谱图可以进一步确定增韧剂在环氧树脂中的
Keywords: High Properties；Composites；Adhesive
环氧树脂胶黏剂具有力学性能高、附着力强等优点，主要用于金属材料的粘接，但其对非金属材料粘接效果较差，如聚乙烯材料（PE）、片状模塑料（SMC）以及复合材料等【1- 。 2】近年来国内外对非金属材料用环氧树脂胶黏剂，尤其是先进树脂基复合材料用环氧胶黏剂的开展了大量的研究工作【3- 。 7】本文采用有机硅液体橡胶增韧环氧树脂胶黏剂，用于非金属材料和复合材料的粘接，获得了较高的力学性能，而且成本低。
2 结果与讨论
2.1 增韧剂含量对改性环氧树脂的粘度分析粘度是环氧树脂工艺性能的重要技术指标，本
文对改性环氧树脂进行了旋转粘度的测试分析，得到树脂粘度随加入增韧剂量的变化规律，如图 2-1 所示：
形成氢键同样较少，因此粘接强度下降。因此，增韧剂的含量为 5phr 最佳。 2.3 增韧剂含量对环氧树脂固化温度的影响
1 实验材料及方法
1.1 原材料环氧树脂 E51：岳阳树脂厂，工业级；200#聚酰
胺：天津延安化工厂，工业级；苄基-2-甲胺：嘉兴市精博化学品有限公司。工业级；有机硅液体橡胶：自制。 1.2 改性环氧树脂的制备
在室温条件下，将 200gE51 型环氧树脂与一定量的有机硅液体橡胶在反应器中混合均匀，加入 1.0g 苄基-2-甲胺作为催化剂，缓慢加热至 150℃，反应 1h，即制得有机硅液体橡胶含量的改性环氧树脂。 1.3 实验方法

复合材料聚合物基体第二章环氧树脂

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2.1引言>>2.1.2环氧树脂生产情况及应用
3）环氧树脂在各行业的分配风电、涂料行业和电子行业复合材料成型用环氧（主要应用于电子行业的印刷电路板）占四分之一。
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2.1引言>>2.1.2环氧树脂生产情况及应用
(1) 汽车工业：是我国四大支柱产业之一，且汽车需求量越来越大，电泳漆、另外维修用漆亦需环氧。 (2)船舶、海洋工业：我国是海洋大国，造船大国， 21世纪是海洋的世纪。船舶、码头设施、海上建筑、钻井平台、输油管道、海水养殖设施等等，需要大量的环氧涂料（防腐、防海洋生物污染）。
5
2.1 引言
1947年美国的DeVoe－Raynolds公司进行了第一次具有工业生产价值的环氧树脂的制造。不久，瑞士的CIBA公司，美国的Shell公司等都开始了环氧树脂的工业化 20世纪50年代初期，环氧树脂在电气绝缘浇铸、防腐蚀涂料、金属的粘结等应用领域有了突破，于是环氧树脂作为一个行业蓬勃地发展起来了
O H2C CH2CH2Cl + ROH
catalyst
H R O C C CH2Cl H2 OH
29
3）水解反应
高温下与碱液接触，会逐步水解成甘油
O H2C CH2CH2Cl OHH2O ClCH2 H C H2 C
(4)电子工业：为我国四大支柱产业之一，发展迅猛。 (5)集装箱工业：我国集装箱工业发展迅猛，已成为世界主要集装箱生产基地（占世界总量的 10%～15%）。集装箱用涂料，主要是环氧树脂。
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2.1引言>>2.1.2环氧树脂生产情况及应用
环氧树脂砂浆地坪
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2.1引言>>2.1.2环氧树脂生产情况及应用

POSS改性环氧树脂制备及性能研究进展文献综述

POSS改性环氧树脂制备及性能研究进展文献综述近年来，随着科学技术的快速发展，环氧树脂作为一种重要的高性能材料得到了广泛的应用。

而POSS作为环氧树脂的一种新型改性剂，具有独特的结构和卓越的性能，引起了广泛的研究兴趣。

本文将综述近年来在POSS改性环氧树脂制备及性能研究方面的最新进展。

首先，POSS改性环氧树脂的制备方法可以分为两类，即物理混合和化学改性。

物理混合是将POSS和环氧树脂机械混合，通过表面张力和分散力使POSS分散在环氧树脂中。

而化学改性是通过共聚或交联反应将POSS与环氧树脂进行共价结合，形成POSS改性环氧树脂。

其次，POSS改性环氧树脂的性能也受到了广泛关注。

研究表明，POSS的加入可以显著改善环氧树脂的力学性能，如增加抗拉强度、弯曲强度和冲击强度。

同时，POSS还可以提高环氧树脂的玻璃化转变温度和热稳定性，减少热膨胀系数和燃烧性能。

此外，POSS改性环氧树脂还具有良好的阻燃性能、耐化学性能和耐热老化性能等。

最后，POSS改性环氧树脂在应用方面也取得了显著的进展。

例如，POSS改性环氧树脂可以用于制备高性能复合材料，如航空航天材料、高性能涂层和电子封装材料等。

此外，POSS改性环氧树脂还可以用于制备低介电常数、低介质损耗的微波介质材料。

另外，POSS改性环氧树脂还可以用于制备纳米复合涂料、纳米填料和纳米复合材料等。

总结起来，POSS改性环氧树脂在制备及性能研究方面取得了显著的进展。

然而，目前仍存在一些问题需要进一步研究解决。

例如，POSS的加入量、POSS在环氧树脂中的分散性以及POSS改性环氧树脂的界面相容性等问题需要深入研究。

同时，对于POSS改性环氧树脂的结构和性能之间的关系还有待深入探索。

我们相信，随着研究的不断推进，POSS改性环氧树脂将在未来得到更广泛的应用。

环氧树脂胶粘剂英语

环氧树脂胶粘剂英语英文回答：Epoxy adhesives are a type of structural adhesive that is widely used in various industries, including aerospace, automotive, and construction. They are known for their excellent bonding strength, durability, and resistance to chemicals and environmental factors. Epoxy adhesives are typically formulated using two components: a resin and a hardener. The resin is the main adhesive component, while the hardener initiates the curing process. When the two components are mixed together, they react to form a strong, cross-linked polymer network that provides the adhesive bond.Epoxy adhesives offer several advantages over other types of adhesives. They have high shear and peel strength, making them ideal for applications where the bonded jointis subjected to significant stress. Epoxy adhesives also exhibit good impact resistance and fatigue strength,ensuring the longevity of the bond under dynamic loading conditions. Additionally, epoxy adhesives have excellent chemical resistance, making them suitable for use in environments with exposure to solvents, acids, and bases.The bonding process of epoxy adhesives involves several steps. The first step is surface preparation, which includes cleaning and roughening the surfaces to be bonded to ensure proper adhesion. The next step is mixing the resin and hardener components in the correct proportions, typically using a 1:1 or 2:1 ratio. The mixed adhesive is then applied to one of the surfaces to be bonded, and the two surfaces are brought together and held in place until the adhesive cures. The curing time of epoxy adhesives can vary depending on the specific formulation and the temperature at which they are applied.中文回答：环氧树脂胶粘剂是一种广泛应用于航空航天、汽车和建筑等行业的结构胶粘剂。

有机累托石／环氧树脂(OREC／EP)复合材料的制备和性能研究

自制热变形温度仪、ＨＩＡＣ一７ＴＨＩ５０型电镜扫描仪、日本理学Ｄ／ＭＡＸ一Ｃ型ｘ射线衍射仪、ＰＳｌ３ＹＲ型ＤＳＣ测试仪、真空系统、油浴加热系统、紫外老
鹱
素
静
化系统，其他常规仪器。
１３配方，
１实验部分
１１原料．
２１ＯＲＣ对树脂体系力学性能的影响．Ｅ按Ｇ５０１８和Ｇ５１１８标准测试Ｂ２７ — ９１Ｂ２７ — ９１
Ｅ５环氧树脂（氧６８：星辰化］无锡树脂一ｌ环ｌ）：厂；２一乙基一一４甲基咪唑：天津天锋化学品公司；有机累托石：自制；ｌ２（２７氯化十二烷基二甲基苄
ｍ（一ｌ氧树脂）ｍ（一Ｅ５环：２乙基一一甲基眯唑）４＝
１０：．０３５
收稿臼期：０８０ — ５２０ — ４２
作者简介：王娟娟（９一，，西礼泉人，究方向为商分子复合材料及胶黏剂的改性、能陶瓷的制备及其改性。１７）女陕７研功
入及其含量对复合材料ＯＲＥＥＰ体系的力学性能、耐介质性能和耐紫外线性能的影响。研究发现：Ｃ／
ＯＥＲＣ是一种良好的环氧树脂增韧改性剂，ＯＥＲＣ的加入可改善复合材料的综合性能。当ＯＥＲＣ质量分数为３时，冲击强度和弯曲强度提高幅度最大，分别为６２％．８３％，耐海水性能效果最好；在添加％．５和．９

AlN／低粘度环氧树脂复合材料的性能研究

ｔｅＡＩｖｌｍｅｆａｔｏｆ４％．ｈＮｏｕｒｃｉｎｏ６
Ｋｅｒｓ：ｉｕａｉｇｍａｅｉｌｔｅｍａ－ｏｄｃｉｇｃｍｐｓｅｔｅｍａｎｕｔｉｙｒｉｉｉｙｙｗｏｄｓｎｌｔｔｒ；ｈｒｌｎｕｔｎｏｏｉ；ｈｒｌｄｃｉｔ；ｅｓｖｔｎａｃｔｏｃｖｓｔ
填料的形态，用纤维状填料代替颗粒状填料［，如７方］
便导热通道的形成。事实上，绝缘导热填料的添加量和综合性能受
具有高的热导率，不绝缘，时耐化学腐蚀性能但同差；高分子材料绝缘性能和耐化学腐蚀性能好，热但导率很低；因此这２种材料都无法满足特殊领域对
维普资讯
国外建材科技
２００８年
第２９卷
第３期
Ａｌｆ度环氧树脂复合材料的性能研究Ｎ／氐粘
徐信，学单刚王钧任鲁林，云，
（汉理工大学材料科学与工程学院，汉４０７）武武３００
ＸＵｎｘｉＬＵｅｌｎ，ＳＲｅ — ｎ，Ｘｕ－ｉＨＡＮｎｇｎ，ＷＡＮＧＪｎＹｕ — ａｇｕ
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木质素环氧树脂复合材料

Thermochimica Acta431(2005)76–80Glass transition and thermal decomposition ofepoxy resins from the carboxylic acid systemconsisting of ester-carboxylic acid derivatives ofalcoholysis lignin and ethylene glycol with variousdicarboxylic acidsShigeo Hirose a,∗,Tatsuko Hatakeyama b,Hyoe Hatakeyama ca National Institute of Advanced Industrial Science and Technology,Central5,Tsukuba,Ibaraki305-8565,Japanb Otsuma Women’s University,12Sanbancho,Chiyoda-ku,Tokyo102-8537,Japanc Fukui University of Technology,3-6-1Gakuen,Fukui910-8501,JapanReceived14October2004;received in revised form10December2004;accepted21January2005Available online23May2005AbstractAlcoholysis lignin(AL)was dissolved in ethylene glycol and the obtained mixture was reacted with succinic anhydride to form a mixture of ester-carboxylic acid derivatives of AL and ethylene glycol(AL-poly(ester-carboxylic acid),ALEGPA).The obtained ALEGPA was mixed with dicarboxylic acids with different alkylene chain length such as succinic acid(alkylene chain,C2),adipic(C4)acid and sebacic acid(C8). The obtained mixture of ALEGPA and dicarboxylic acid was reacted with ethylene glycol diglycidyl ether in the presence of a catalytic amount of dimethylbenzylamine to form ester-epoxy resins.The curing reaction was carried out at130◦C for5h.The molar ratio of epoxy groups to carboxylic acid groups([EPOXY]/[AA]ratios,mol/mol)was1.0.The ALEGPA content in the above mixture was varied from0to100%. Thermal properties of epoxy resins were studied by differential scanning calorimetry(DSC)and thermogravimetry(TG).Glass transition temperatures(T g’s)increased with increasing ALEGPA contents,suggesting that lignin acts as a hard segment in epoxy resin networks.The values of T g’s of epoxy resins with dicarboxylic acids increased in the following order;epoxy resins with succinic acid(alkylene chain,C2), adipic acid(C4)and sebacic acid(C8).Thermal degradation temperatures(T d’s)of epoxy resins slightly decreased with increasing ALEGPA contents.The values of mass residue at500◦C(MR500)increased with increasing AL contents in epoxy resins and also with decreasing chain lengths of dicarboxylic acids.©2005Elsevier B.V.All rights reserved.Keywords:Glass transition;Thermal decomposition;Epoxy resins;Alcoholysis lignin;Aliphatic dicarboxylic acids1.IntroductionLignin is recognized as one of the most important renew-able resources,since the amount of production is very large [1].Lignin has a highly branched chemical structure con-sisting of phenyl propane units which are connected mainly by ether linkage.It is known that lignin shows insufﬁcient ∗Corresponding author.Tel.:+81298616250;fax:+81298616250.E-mail address:s-hirose@aist.go.jp(S.Hirose).mechanical properties in solid state as a polymeric material [2].Many attempts in chemical and physical modiﬁcations of lignin have been made in order to solve the above problems in its utilization as a polymeric material.In the last10years, we have extensively studied synthetic polymers from lignin [3,4].In the above studies,synthetic polymers were derived from lignin on the basis of molecular design concerning the basic structures such as phenyl propane units,and also the functional groups in lignin molecules such as hydroxyl and methoxyl groups.Recently,it was found that polyurethanes0040-6031/$–see front matter©2005Elsevier B.V.All rights reserved. doi:10.1016/j.tca.2005.01.043S.Hirose et al./Thermochimica Acta431(2005)76–8077derived from lignin and also from lignin-based caprolactones show excellent thermal and mechanical properties and also biodegradability[5–9].Epoxy resins are recognized as one of the important ther-moset polymers,since they are used in various materials such as adhesives,matrix of composites and elastomers. In the past,many researchers studied ether type of lignin-based epoxy resins prepared from lignin[10–12].Recently, aliphatic polyesters,such as polycaprolactones,poly ethy-lene succinate,polylactic acid,have received considerable attention due to the fact that they are biodegradable.In our previous study,we investigated synthesis and thermal prop-erties of the ester type of epoxy resins,which can be derived from lignin,polyethylene glycol diglycidyl ether and azelaic anhydride[13].We also studied epoxy resins which can be prepared from an ester-carboxylic acid derivative of lignin synthesized from alcoholysis lignin(AL)and succinic acid anhydride.The obtained ester-carboxylic acid derivative of AL(ALEGPA)was reacted with ethylene glycol diglycidyl ether(EGDGE)to form epoxy resins under various condi-tions.The behavior in curing reactions was studied by differ-ential scanning calorimetry(DSC).Furthermore,the thermal properties of the obtained epoxy resins were studied by DSC and thermogravimetry(TG)[14].In the present study,epoxy resins were prepared from a carboxylic acid system consist-ing of ALEGPA with aliphatic dicarboxylic acids with dif-ferent alkylene chain lengths such as succinic acid(alkylene chain,C2),adipic acid(C4)and sebacic acid(C8).The ther-mal properties such as glass transition and thermal decompo-sition of the obtained epoxy resins were studied by DSC and TG.The inﬂuence of the difference in chemical structure of epoxy resins on thermal properties is investigated.2.Experimental2.1.MaterialsAlcoholysis lignin(AL)was kindly supplied by Repap Co.,USA,and was dried in vacuum at70◦C.Other reagents such as ethylene glycol(EG),ethylene glycol diglycidyl ether(EGDGE),dimethylbenzylamine(DMBA),succinic acid,adipic acid and sebacic acid were commercially ob-tained from Wako Pure Chemical Industries Ltd.,Japan.The above reagents were used without further puriﬁcation.2.2.Preparation of epoxy resinsAL polyacid(ALEGPA)was prepared from AL,EG and succinic anhydride,according to the method previously re-ported[14].ALEGPA and a dicarboxylic acid(DCA)was mixed well with EGDGE at80◦C,and the mixture was al-lowed to stand at130◦C for5h in an oven.Each of succinic acid,adipic acid and sebacic acid was used as an aliphatic di-carboxylic acid(DCA).The molar ratios of carboxylic acid groups to epoxy groups[EPOXY]/[ACID]ratio(mol mol−1)was maintained at1.0.ALEGPA contents were varied at0, 20,40,60,80and100%.The[EPOXY]/[ACID]ratios and the ALEGPA contents were calculated by the following equa-tions:[EPOXY]/[ACID]ratio(mol/mol)=(M EGDGE W EGDGE)/ (M ALEGPA W ALEGPA+M DCA W DCA),ALEGPA content(%) =[W ALEGPA/(W ALEGPA+W DCA)]×100where M EGDGE is the mole number of epoxy groups per gram of EGDGE(7.7mmol g−1),W EGDGE the weight of EGDGE, M ALEGPA the mole number of carboxylic acid groups per gram of ALEGPA(6.62mmol g−1),W ALEGPA the weight of ALEGPA,M DCA the mole number of carboxylic acid groups per gram of DCA,W DCA the weight of DCA.2.3.MeasurementsA Perkin-Elmer Spectrum One Fourier transform infrared spectrometer equipped with a universal ATR unit was used for infrared spectrometry.A Seiko DSC220was used for dif-ferential scanning calorimetry(DSC).The measurements of glass transition of epoxy resins were carried out ranging from −60to80◦C at a heating rate of10◦C min−1using ca.5mg of samples.The samples were heated to130◦C and main-tained for10min,and then they were quenched to−60◦C in DSC aluminum vessels before measurements.The glass transition temperatures(T g’s)were determined according to a method reported by Nakamura et al.[15].A Seiko TG/DTA 220was used for thermogravimetry(TG).The measurements were carried out using ca.5mg of samples at a heating rate of10◦C min−1in nitrogenﬂow of300mL min−1.Thermal decomposition temperatures(T d’s)were determined accord-ing to a method reported by Hatakeyama and coworkers [16].3.Results and discussionIn the present study,epoxy resins were obtained by the reaction of a mixture ALEGPA/DCA with EGDGE. The reaction scheme is shown in Scheme1.The chemical structure of the obtained ALEGPA is conﬁrmed by FT-IR. FT-IR spectrum of ALEGPA is shown in Fig.1.The characteristic absorption peaks of carboxylic acid groups at1780,around2700and3200cm−1,and also of ester groups at1720,1200cm−1are observed in the spectrum. The FT-IR spectrum of an epoxy resin with succinic acid with ALEGPA content60%after curing at130◦C for5h is also shown in Fig.1.The characteristic absorption peaks for ester groups1720and1200cm−1and also hydroxyl groups at3300cm−1are observed.Glass transition of epoxy resins was studied by DSC.Fig.2 shows DSC curves of epoxy resins with various ALEGPA contents.A heat capacity gap in baseline due to glass transi-78S.Hirose et al./Thermochimica Acta 431(2005)76–80Scheme 1.Reaction scheme for the preparation of epoxyresins.Fig.1.FT-IR spectra of ALEGPA,EGDGE and an epoxy resin with succinicacid.Fig.2.DSC curves of epoxy resins with various ALEGPA contents in a ALEGPA/succinic acid system.Numbers indicate ALEGPA contents.tion is observed in each DSC curve.T g ’s change according to the change in ALEGPA contents of epoxy resins in the ALEGPA/succinic acid system.Fig.3shows the relationship between T g and ALEGPA content of epoxy resins with dicar-boxylic acids (DCA)with various alkylene chain lengths.T g increases with increasing ALEGPA content of epoxy resin.The above results indicate that lignin acts as a hard segment in epoxy resin molecules.It is known that lignin is a highly branched polymer consisting of phenylpropane units mainly connected by ether linkage.It has also a number of hydroxyl groups in a molecule [1].Therefore,it is considered that lignin exists as cross-linking points.The chain lengths of epoxy resins between cross-linking points decrease with in-creasing ALEGPA content in epoxy resins.The increase in the chain lengths between cross-linking points enhances the main chain molecular motion.The T g values are high intheFig.3.Relationship between T g and ALEGPA content of epoxy resins with DCA with various alkylene chain lengths.C 2(᭹),C 4( )and C 8( ).S.Hirose et al./Thermochimica Acta 431(2005)76–8079Fig.4.TG and differential TG (DTG)curves of the starting materials such as ALPA,EGDGE and AL.order of epoxy resins with succinic acid (C 2),adipic acid (C 4)and sebacic acid (C 8).The above results are reasonable when we consider that the ﬂexibility of main chains in epoxy resin molecules increases with increasing chain lengths of dicarboxylic acids.Thermal decomposition behavior of starting materials and epoxy resins was studied by TG.Fig.4shows TG and dif-ferential TG (DTG)curves of the starting materials such as ALEGPA,EGDGE and AL.TG and DTG curves of DCA are not shown in Fig.4,since only the evaporation of the above compounds was observed in TG measurements.It is observed that thermal decomposition apparently proceeds in two steps.T d ’s at lower temperature regions (T d1)and also T d ’s at higher temperature regions (T d2)were determined.T d1’s of the start-ing materials are 189.6and 133.3◦C while T d2’s 335.3and 233.2◦C,respectively.It is known that epoxy groups are rel-atively unstable [17].Accordingly,it is considered that the above group starts to decompose at T d1region.Fig.5shows TG and differential TG (DTG)curves of epoxy resins with various ALEGPA contents in the ALEGPA/DCA systems with succinic acid,adipic acid and sebacic acid.It is observed that the decomposition apparently proceeds in a smooth step.The thermal degradation at T d1re-gion,that is observed in TG curves of the startingmaterialsFig.5.TG and differential TG (DTG)curves of epoxyresins.Fig.6.Relationship between T d ALEGPA content of epoxy resins.C 2(᭹),C 4( )and C 8( ).(Fig.4),is not observed.This indicates that thermally un-stable carboxylic acid and epoxy groups were converted into thermally stable ester groups.Thermal decomposition tem-peratures (T d ’s)and mass residue at 500◦C (MR 500)were determined from TG curves.Fig.6shows the relationship be-tween T d and ALEGPA content of epoxy resins.T d slightly decreases with increasing ALEGPA content.However,the degree of the decrease in T d values is very small.It is known that lignin is relatively thermally unstable [6].As shown in Fig.4,T d of AL was determined as 284.3◦C.The T d values of epoxy resins from AL are much higher than that of AL.There-fore,it can be considered that lignin becomes thermally stable after introduction into the epoxy resin molecules.As shown in Fig.6,T d values are almost the same regardless of the dif-ference in alkylene chain lengths of DCA.In order to clarify the inﬂuence of lignin in epoxy resins on MR 500values,AL contents in epoxy resins were calculated.The relationship be-tween AL contents and MR 500is shown in Fig.7.As clearly seen in Fig.7,MR 500values increase with increasing AL con-tents in epoxy resins.It is known that lignin molecules react with each other to form a condensed char-like material,when they are heated in nitrogen.Therefore,it is considered that the materials in the residue at 500◦C are mainly formed by the reaction with lignin in epoxy resins during the decompo-sition process.The above consideration can be supported by the fact that the MR 500value of ALEGPA is higher than that of SA,as shown in Fig.4.As shown in Fig.7,MR 500vales are always high in the order of epoxy resins with succinic acid (C 2),adipic acid (C 4)and sebacinic acid (C 8),suggesting that dicarboxylic acids with longer alkylene chains give smaller amounts of residual materials after thermal decomposition up to 500◦C.However,the above difference in MR 500values be-comes smaller when AL contents are increased.Accordingly,it can be said that the AL contents in epoxy resins strongly affect MR 500values in the higher AL contents region.80S.Hirose et al./Thermochimica Acta431(2005)76–80Fig.7.Relationship between MR500’s and AL contents in epoxy resins.C2 (᭹),C4( )and C8( ).4.ConclusionEpoxy resins were obtained by the reaction of the ester-carboxylic acid derivatives of alcoholysis lignin (ALEGPA)/aliphatic dicarboxylic acids(DCA)system with EGDGE.T g increased with increasing ALEGPA contents in epoxy resins,suggesting that lignin acts as a hard segment in epoxy resins.It was found that T g’s of epoxy resins decreased with increasing alkylene chain lengths of dicarboxylic acids from C2to C8.T d slightly decreased with increasing ALEGPA content in epoxy resin.The difference in alkylene chain length of DCA does not affect T d values of epoxy resins,while it affects MR500values.It was also found that AL contents in epoxy resins strongly affect MR500values particularly in the higher AL contents region.References[1]K.Kringstad,in:L.E.St.Pierre,et al.(Eds.),Future Sources ofOrganic Raw Mterials—CHEMRAWN I,Pergamon Press,1980,p.627.[2]G.Dai,in:K.V.Sarkanene, C.H.Ludwig(Eds.),Lignins,Wi-ley/Interscience,New York,1971,p.697.[3]H.Hatakeyama,J.Therm.Anal.Calorimetry70(2002)755–795.[4]T.Hatakeyama,H.Hatakeyama,Thermal Properties of GreenPolymers and Biocomposites,Kluwer Academic Publishers, 2004.[5]K.Nakamura,T.Hatakeyama,H.Hatakeyama,Polym.Adv.Technol.2(1992)41–47.[6]S.Hirose,K.Kobashigawa,Y.Izuta,H.Hatakeyama,Polym.Int.47(1998)247–256.[7]H.Hatakeyama,Y.Izuta,S.Hirose,T.Yoshida,T.Hatakeyama,in:J.F.Kennedy,P.A.Williams,G.O.Phillips,H.Hatakeyama(Eds.), Recent Advances in Environmentally Compatible Polymers,Wood-head Publisher Ltd.,Chichester,2001,pp.33–46.[8]T.Hatakeyama,Y.Izuta,S.Hirose,H.Hatakeyama,Polymer43(2002)1177.[9]S.Hirose,T.Hatakeyama,Y.Izuta,H.Hatakeyama,J.Therm.Anal.Calorimetry70(2002)853–860.[10]D.Feldman, D.Banu,J.Polym.Sci.,Polym.Chem.26(1988)973–983.[11]H.Ito,N.Shiraishi,Mokuzai Gakkaishi33(1987)393–399.[12]K.Hofmann,W.G.Glasser,Macromol.Chem.Phys.195(1994)65–80.[13]S.Hirose,M.Kobayashi,H.Kimura,H.Hatakeyama,in:J.F.Kennedy,P.A.Williams,G.O.Phillips,H.Hatakeyama(Eds.),Re-cent Advances in Environmentally Compatible Polymers,Woodhead Publisher Ltd.,Chichester,2001,pp.73–78.[14]S.Hirose,T.Hatakeyama,H.Hatakeyama,Macromol.Symp.197(2003)157–169.[15]S.Nakamura,M.Todoki,K.Nakamura,H.Kanetsuna,Thermochim.Acta136(1988)163–178.[16]T.Hatakeyama, F.X.Quin,Thermal Analysis,Wiley,Chichester,1994,pp.38–64.[17]J.D.Roberts,M.C.Caserio,Basic Principles of Organic Chemistry,2nd ed.,Wiley,New York,1980,pp.661–665.。

耐高温拉挤环氧树脂及其复合材料性能研究

耐高温拉挤环氧树脂及其复合材料性能研究王成忠 1 陈伟明1梁平辉2杨小平1(1北京化工大学碳纤维及复合材料研究所，北京 1000292 常熟佳发化学有限责任公司，常熟 215533)摘要：研究了------型耐高温环氧树脂的固化动力学，分析了该树脂体系的浇注体性能，制备了碳纤维拉挤复合材料，并通过热机械分析（DMTA）考察了树脂浇注体及其复合材料的动态热机械性能。

结果表明，树脂体系的凝胶化温度与固化温度相差较小，固化反应放热集中，适合于快速拉挤成型，其复合材料具有优良的耐高温性能，Tg达到210℃以上。

关键词：耐高温拉挤成型环氧树脂复合材料keywords: heat-resistance pultrusion epoxy resin composites前言拉挤成型是制造高性能、低成本连续复合材料的一种重要方法，拉挤成型工艺要求基体树脂应具有反应速度快、粘度低、适用期长等特点，常用的快速拉挤用树脂主要是自由基固化型的不饱和聚酯树脂和乙烯基酯树脂[1,2]。

此类树脂的拉挤工艺性能优良，但存在耐热性能较低的缺点，虽然部分树脂品种具有较好的耐热性，但其固化物的Tg一般不高于180℃[3]，而且对于高性能碳纤维拉挤复合材料往往存在界面性能较差的问题[4]。

采用环氧树脂制备的碳纤维复合材料具有优良的力学性能，但对通用型环氧树脂来说，以胺类固化剂的树脂体系粘度较大，添加稀释剂后力学性能和热性能会大幅度下降；以液体酸酐为固化剂的树脂体系往往需要高温长时间固化，所以环氧树脂较少用于拉挤成型。

高性能拉挤复合材料的发展，急需可适用于拉挤成型工艺的高性能环氧树脂，要求树脂具有反应速度快、耐热性能高、强度高等特点。

通过对通用型环氧树脂进行改性虽可以获得较高的耐热性能[5]，但难以适用于规模化生产。

本文研究了一种改性多元芳香族缩水甘油胺型环氧树脂的固化特性，并与液体酸酐配合进行了拉挤成型工艺研究，认为该树脂体系具有优良的拉挤工艺性能，其碳纤维拉挤复合材料的耐热性达到210℃以上，该树脂克服了常规耐高温环氧树脂粘度高、使用工艺性差的缺点，具有良好的加工工艺性，是一种新型的耐高温拉挤树脂。

一篇关于复合材料非常好的一篇英文文献

Hydrogen-storage materials dispersed into nanoporous substrates studied through incoherent inelastic neutron scatteringD.Colognesi a ,⇑,L.Ulivi a ,M.Zoppi a ,A.J.Ramirez-Cuesta b ,A.Orecchini c ,A.J.Karkamkar d ,M.Fichtner e ,E.Gil Bardajíe ,Z.Zhao-Karger eaConsiglio Nazionale delle Ricerche,Istituto dei Sistemi Complessi,Via Madonna del Piano 10,50019Sesto Fiorentino (FI),Italy bISIS Facility,STFC Rutherford Appleton Laboratory,Harwell Oxford,Didcot OX110QX,United Kingdom cInstitut Laue-Langevin,6Rue Jules Horowitz,38042Grenoble Cedex 9,France dPaciﬁc Northwest National Laboratory,P.O.Box 999,Richland,WA 99352,USA eKarlsruhe Institute of Technology,Institute of Nanotechnology,Hermann-von-Helmholtz-Platz 1,76347Eggenstein-Leopoldshafen,Germanya r t i c l e i n f o Article history:Received 26March 2012Received in revised form 18May 2012Accepted 18May 2012Available online 30May 2012Keywords:Hydrogen storage Nanomaterials Lattice dynamicsInelastic neutron scatteringa b s t r a c tIncoherent inelastic neutron scattering measurements on four impregnated/inﬁltrated composites of hydrides (namely,NaAlH 4,NH 3BH 3,LiBH 4+Mg(BH 4)2,and MgH 2)plus nanoporous scaffolds (active car-bon ﬁbers or silica-based MCM41)have been performed at low temperature.After a careful data analysis,the present experimental results have been compared to the corresponding spectroscopic data of bulk hydrides.Evident signatures induced by inﬁltration process on the NaAlH 4phonon bands have been detected,showing up as a strong peak broadening and smoothing together with,in some cases,an energy shift.Less pronounced phonon spectrum modiﬁcations have been found in MgH 2and NH 3BH 3,mainly concentrated in the low-energy acoustic region.Finally,no relevant effect has been observed for LiBH 4+Mg(BH 4)2.Ó2012Elsevier B.V.All rights reserved.1.IntroductionHydrogen is currently studied as a possible environment-friendly and efﬁcient energy carrier in connection with the future exploitation of alternative and/or renewable energy sources [1].The construction of an effective and reliable storage system is one of the key issues in the use of hydrogen as an energy carrier alternative to liquid and gaseous hydrocarbons [2].In this perspec-tive one can note that various complex ionic hydrides based on Al (alanates),N (amides)and B (boranates)[3–5]exhibit a very high hydrogen content,close or even exceeding the 2015target (i.e.,9wt.%)for hydrogen storage systems set by the US Department of Energy (DOE)[6].Nevertheless,although these materials are in principle highly interesting,they still cannot be used in technical applications,mainly due to the following reasons:(1)The thermodynamic properties of the pure hydride phasesare not appropriate because these materials are often too stable.This fact implies decomposition temperatures higher than 200°C,which are particularly undesirable in automo-tive applications.(2)The hydrogenation/dehydrogenation kinetics of the purehydride phases is too slow for practical purposes.It has been shown in several cases [7]that the transformation processes are dominated by the sluggish material-transport kinetics.(3)The reversibility upon cycling is hampered by the separationof phases appearing during the dehydrogenation of the material.These phases may segregate and grow,leading to a slowdown of the kinetics and the formation of inert frac-tions in the sample which cannot be re-hydrogenated upon cycling.Particles aggregation is also seen as a potential risk causing the formation of a bulk-like hydride.In order to tackle these problems,several strategies have been suggested.A promising approach is based on the well-known fact that the enthalpy of formation of a material is lowered in most cases [8]by increasing its surface energy [9].Thus it is possible to attain hydride destabilization by decreasing the particle size,reaching lower hydrogen-release temperatures.In general,parti-cles having nano-scale sizes are characterized by different thermo-dynamics,enhanced surface interactions,faster kinetics,increased number of defects,modiﬁed phase transformations,as well as the occurrence of new and meta-stable phases.Most of the work accomplished so far in order to achieve active hydride nano-particles has made use of the so-called scaffolding0925-8388/$-see front matter Ó2012Elsevier B.V.All rights reserved./10.1016/j.jallcom.2012.05.081Corresponding author.Tel.:+390555226681;fax:+390555226683.E-mail address:daniele.colognesi@ﬁr.it (D.Colognesi).technique.By the word‘‘active’’we mean a material exhibiting appropriate thermodynamic conditions and fast dynamics,but rid of phase separation and other unwanted effects.In this respect, it has been suggested[10]that the incorporation of hydrogen stor-age materials into micro-and meso-porous rigid structures would stabilize nanomaterials and prevent aggregation during cycling. Thus,the hydride would retain the thermodynamic parameters and kinetic behavior associated with the hydrogenation/rehydro-genation of the nanomaterial rather than reverting to the standard bulk material when cycled.Several nanoporous scaffold-conﬁned hydrogen storage materials have been reported so far,and most of them are carbonaceous structures,including active carbonﬁ-bers[11],carbon aerogels[12],and even C20-and C60-based solids [13].On the other hand,in the ammonia borane case,Gutowska et al.[14]have developed a way to deposit the active material within the channels of mesoporous silica(i.e.,SBA-15).The silica increases the rate of hydrogen release from the NH3BH3by two orders of magnitude compared with the release of hydrogen from the pristine compound.Furthermore,heating the hybrid material above100°C to release the second equivalent of hydrogen(i.e., the second H2molecule)gives rise to very little amount of borazine.Although a number of preparation methods are being devel-oped to disperse hydrogen containing materials into nano-porous matrices(e.g.,melt inﬁltration,wet impregnation,etc.),the phys-ical properties of such nano-dispersed complex systems have not yet been fully investigated.In particular,there is a lack of under-standing with respect to the inﬂuence of the particle size and the nature of the particle interface on hydride binding energies.A de-tailed analysis of the vibrational properties will be an essential contribution to this new and both scientiﬁcally and technically interestingﬁeld.Actually,some incoherent inelastic neutron scat-tering(IINS)measurements have been recently performed on so-dium alanate,pristine and inﬁltrated into activated carbonﬁber (namely,in ACF25from Kynol Inc.with most of the pores ranging between0.5and4nm)[15].The neutron spectrum of the pristine material(i.e.,NaAlH4)appears very rich in sharp spectral features caused by the proton vibrational dynamics in the system.On the contrary,the spectrum of the inﬁltrated material is completely disrupted by the nano-conﬁning action of the matrix,ending up in an almost complete hydride amorphization.In addition,the inter-ionic vibrational modes turn out to be substantially weak-ened,while the intra-ionic ones are strengthened.So it is valuable to know if similar effects are observed after changing:hydroge-nated compound(i.e.,from NaAlH4to MgH2,LiBH4+Mg(BH4)2, and NH3BH3);pore shape(i.e.,from roughly spherical to cylindrical);pore size(i.e.,from dispersed between0.5and 4nm to aﬁxed diameter of4.0nm);substrate(i.e.,from graphitic carbon to silica).This is exactly the objective of the present comparative work.Data related to nanoconﬁned NaAlH4will be presented again for comparison,but with a completely different aim with respect to Ref.[15]:in the present study the same technique is used to characterize various samples(representative of the main classes of H-containing systems),while in the aforementioned paper two different techniques(i.e.,IINS and Raman)have been applied to the same nanoconﬁned sodium alanate sample.The paper is organized as follows:the sample synthesis is de-scribed in detail in the next section,followed in Section3by the experimental IINS procedure,while all the data reduction details are reported in Appendix A.In Section4,the present experimental results are thoroughly analyzed,also in connection with previous spectroscopic measurements and,if existing,ab-initio density-functional theory simulations.Finally,the last section contains the conclusions of the present work.2.Sample synthesisEven though the synthesis details have been reported elsewhere(namely in Refs.[14,16–18],respectively,for NH3BH3,NaAlH4,MgH2,and Mg(BH4)2),it is worthwhile to describe in detail what kinds of materials have been investigated by neutron spectroscopy,mainly focusing on the nature and the differences of their respective scaffoldings:(1)sodium aluminum tetrahydride(NaAlH4,from Albemarle Corp.,purity96%)was employed as received,while,prior to use,activated carbonﬁbers ACF25(from Kynol Inc.)were milled in a planetary ball mill so to obtain aﬁne powder according to the following conditions:10.0g of ACF25con-tained in a silicon nitride vial with six balls of13.0g each rotating at about 550rpm.Six milling cycles30min long were accomplished,each one fol-lowed by a5min pause.Subsequently the ground product was treated under Ar plus H2(i.e.,with5%of H2)atmosphere at600°C overnight,in order to remove moisture and oxygen containing surface groups.ACF25is deﬁned as both a micro-and a mesoporous carbonaceous material,with most of the pores ranging between0.5and4nm and peaked at0.8nm[19].Its surface area,measured via the Brunauer,Emmet,and Teller(BET)method,was1815m2/g,while its free pore volume was estimated to be0.66cm3/g(for pore widths below4nm and after ball milling).A mixtureof NaAlH4(1.85g)and ground ACF25(1.85g)was lightly ball-milled,trans-ferred into an autoclave,and then heated under hydrogen atmosphere(150 barﬁnal pressure)to190°C(1h soaking time),i.e.,slightly above the melt-ing temperature of NaAlH4.The characteristics of the melt-inﬁltrated com-posite were completely different from those of pure ACF25:the surface area was reduced to242m2/g and the free pore volume to0.09cm3/g only,indi-cating that the largest portion of NaAlH4was inside the pores and not only on the external part of the carbonﬁbers.Thus at the end of the synthesis procedure the following melt-inﬁltrated NaAlH4+ACF25sample were available:NaAlH4:ACF25=1:1by weight,m=2.5g.(2)MCM-41silica was obtained from Mobil Corporation,while ammonia bor-ane was synthesized according to the procedure reported in Ref.[20]and puriﬁed by sublimation in vacuum.In order to disperse NH3BH3into the porous substrate,a solution of ammonia borane(m=5.6g,containing iso-topically enriched11B to reduce neutron absorption)in tetrahydrofuran (about100cm3)was slowly added to a sample of MCM-41(11.2g).The solution appeared to haveﬁlled the internal channels of the mesoporous scaffold by capillarity.The impregnated MCM-41was then dried under vac-uum so to produce a sample with an internal coating of ammonia borane (approximately1:2NH3BH3to MCM-41by weight).As for the porous silica presently used,it exhibited a relatively large surface area(700–800m2/g from BET)and a medium-sized primary pore width(diameter:4.0nm), being formed by an ordered hexagonal array of cylindrical channels witha very regular morphology(space group P6mm).For this reason it was easyto calculate the total pore volume,which was in the range0.7–0.8cm3/g. (3–4)The two samples containing MgH2or LiBH4+Mg(BH4)2were obtained mak-ing use of ACF25or IRH33activated carbon,respectively.The latter,pro-duced at the Institut de recherche sur l’hydrogène of Universitédu QuébecàTrois-Rivières(Canada)was prepared by carbon dioxide activation of a car-bonaceous material(namely,coal from coconut shells)and showed a pore distribution from0.5to4.0nm,peaked at2.75nm.The physisorption mea-surement of IRH33revealed a BET surface area of2587m2/g and a micro-pore volume of about1.2cm3/g.IRH33was used after being ground by mortar and pestle so to get aﬁne powder material.Then a eutectic mixture of LiBH4+Mg(BH4)2(m=0.28g,containing isotopically enriched7Li and11B to reduce the sample neutron absorption)was dispersed into0.73g of IRH33by melt inﬁltration at180°C under30bar-pressure of H2for1h.Theﬁnal concentration was estimated to be LiBH4+Mg(B-H4)2:IRH33=1:2.6by weight.This composite has been characterized by means of X-ray diffraction and electron microscopic methods.The inﬁl-trated composite did not present any Bragg peaks and also no particles were visible in the transmission electron microscopy(TEM)images.The concen-tration of Mg,B and C have been mapped by energy-dispersive X-ray(EDX) and electron energy loss(EELS)spectra,where the homogeneous distribu-tion of the elements within the map indicates that borohydrides have been homogeneously incorporated within the carbon scaffold.These results are the indication of nanodispersion and/or amorphization of the borohydrides within the carbon scaffold.As for the MgH2sample,a dibutyl magnesium(Bu2Mg)solution was slowly added to pre-treated ACF25at room temperature,and then the mixture was quenched into liquid nitrogen in order to draw up all the precursor into the carbon ter,the solvent was removed under dynamic vacuum at a gradually increasing temperature for5h.This procedure of carbon impregnation/drying was repeated several times so to prevent the excess of Bu2Mg from sticking on the surface of the carbon material:at the end,18cm3of Bu2Mg solution had been added to2.0g of ACF25and dried.Then the composite was hydrogenated by heat-92 D.Colognesi et al./Journal of Alloys and Compounds538(2012)91–99ing up the sample to180°C under60bar of H2,causing the decomposition of Bu2Mg into MgH2and butane.Finally,the prepared composite containing20wt.%of MgH2 was again ground in a mortar under argon atmosphere producing aﬁne powder.3.Experimental neutron scattering proceduresFour distinct neutron scattering experiments have been per-formed,namely:on sodium alanate inﬁltrated into ACF25(I),on LiBH4+Mg(BH4)2inﬁltrated into IRH33activated carbon(II),on ammonia borane dispersed into MCM41mesoporous silica(III), andﬁnally on magnesium hydride dispersed into ACF25(IV).The ﬁrst and the third IINS measurements have carried out on TOS-CA-II[21]spectrometer,while the remaining two on IN4C spec-trometer[22].For this reason the description of the experimental procedure has been split into two separate parts:Section3.1deal-ing with the TOSCA-II experiments,and Section3.2dealing with the IN4C ones.3.1.Incoherent inelastic neutron scattering on TOSCA-IIThe neutron scattering measurements on samples(I)and(III) were carried out using TOSCA-II inelastic spectrometer of the ISIS pulsed neutron source at Rutherford Appleton Laboratory(Harwell, Didcot,Oxon,UK),according to the scheme reported in Table1.TOS-CA-II is a crystal-analyzer inverse-geometry spectrometer[21], where theﬁnal neutron energy is selected by two sets of pyrolytic graphite crystals placed in forward scattering(at around42.6°with respect to the incident beam)and in backscattering(at about137.7°with respect to the incident beam).This arrangement sets the nom-inal scattered neutron energy to E1=3.35meV(forward scattering) and to E1=3.32meV(backscattering).Higher-order Bragg reﬂec-tions areﬁltered out by120mm-thick beryllium rods,wrapped in cadmium and cooled down to a temperature lower than30K.The incident neutron energy,E0,on the other hand,spans a broad range allowing to cover an extended energy transfer(E=E0ÀE1)region: 3meV<E<500meV.Because of theﬁxed geometry of this spec-trometer,the wave-vector transfer,Q,is related to the energy trans-fer through a monotonic function,roughly proportional to the square root of the incoming neutron energy:Q¼Q F;BðE0Þ/E1=20 (where sufﬁxes F or B stand for forward scattering or backscattering, respectively).TOSCA-II has an excellent energy resolution in the accessible energy transfer range(D E/E0=1.5–3%).The sample cell used for the inﬁltrated sample(I)was an airtight indium-sealed cylinder made of vanadium(75.0mm long, 15.0mm internal diameter,wall0.4mm thick);while for sample (III)-b a standardﬂat can made of aluminum(47.0Â34.0mm2, 3.0mm-internal gap,wall0.5mm thick)was employed.Finally, for sample(III)-a an airtight copper-sealed cylinder made of stain-less steel(60.0mm long,15.0mm internal diameter,wall2.5mm thick)was preferred in order to perform an in situ thermal treat-ment at the end of the experiment(not dealt with in the present study).Special care was taken to prevent possible hydride wetting and oxidation during the sample loading procedure,performed in an inert-gas glove-box.Before the actual measurements,the empty cells were cooled down to the low temperature value of the exper-iment,and their time-of-ﬂight spectra were recorded up to ade-quate integrated proton current(IPC)values.Then the samples were placed into the cryostat,one after the other,and the real neu-tron scattering measurement started when the sample tempera-ture reached approximately20K.The stability of the temperature conditions during these experiments was not regarded as particu-larly important.So for sample(I)the cryostat was left slowly reach-ing its base temperature T’12K,while for samples(III)the controller was set to T=20K.The obtained average temperature values(together with their stabilities)are reported in Table1.3.2.Incoherent inelastic neutron scattering on IN4CThe neutron scattering measurements of the inﬁltrated/impreg-nated samples(II)and(IV)were performed using IN4C spectrom-eter located at the Institut Laue-Langevin(Grenoble,France), following the scheme of Table2.IN4C[22]is a so-called hybrid-geometry spectrometer,where a crystal monochromatorﬁxes the initial neutron energy,and a chopper system determines theﬁnal neutron energy by time-of-ﬂight analysis.The thermal neutron beam emerging from the reactor isﬁrst collimated(divergence, 1°)before impinging,with a Bragg angle varying between39°and65°,on the double focusing monochromator[23].In the case of our experiment,the selected values of initial energy were: E0=83.4meV from the(220)Bragg reﬂection of an array of copper crystals,and E0=149.2meV from the(006)Bragg reﬂection of an array of pyrolitic graphite(PG)crystals.Two rotating disk choppers are used to minimize background neutrons and gamma rays com-ing from the moderator.The long neutron pulses produced by the disk choppers travel through a collimating diaphragm and a sap-phireﬁlter is used to suppress contaminations from higher-order monochromator reﬂections.The beam isﬁnally reduced to short pulses by a Fermi chopper and hits the sample after passing through another collimating diaphragm.Neutrons scattered by the sample are then collected by3003He tubes covering angles up to120°.In addition,a3He-ﬁlled multidetector allows to observe forward scattering down to an angle of about3°.The scattering cells used for both samples(II)and(IV)were air-tight indium-sealed cylinders made of aluminum,(60.0mm long, wall0.5mm thick),but exhibiting two different internal diame-ters:7.5for(II)and15.0for(IV).Special care was taken to prevent possible hydride wetting and oxidation during the sample loading procedure,performed in an inert-gas glove-box.Before the actual measurements,the empty cells were cooled down to the low tem-perature value of the experiment,and their neutron spectra were recorded up to adequate counting time(s)values.Then the men-tioned samples were placed into the cryostat,one after the other, and the real neutron scattering measurement started when the sample temperature reached15K.The obtained temperature val-ues(together with their stabilities)are reported in Table2.For samples(IV)a monochromator change from Cu(220)to PG (006)was performed at the end of the run with E0=83.4meV, without varying the thermodynamic conditions of the sample un-der investigation.4.DiscussionThis section is divided into four subsections:in each of them a detailed comparison between the IINS spectrum of a selected bulk sample and that of the corresponding inﬁltrated/impregnatedTable1Experimental conditions of the IINS measurements on samples(I)and(III)performed on TOSCA-II,including:temperature T,integrated proton current of the ISIS neutron source IPC,total sample mass M,and proton concentration(molar)c[H].Label Sample T(K)IPC(l A h)M(g)c[H](%)(I)Inf.NaAlH4+ACF2516±21263.8 2.5038.11(III)-a Impr.NH3BH3+MCM4119.91±0.021006.3 1.6354.04 (III)-b Pure MCM4119.8±0.6580.20.990.00D.Colognesi et al./Journal of Alloys and Compounds538(2012)91–9993material will be shown,taking into account,if available,appropri-ate published IINS data and lattice dynamics simulations in order to make the spectral interpretation and assignment easier.It worth noting at this stage that the neutron spectra presented in the fol-lowing(with the exception of that from sample(III))represent the so-called hydrogen-projected density of phonon states[24] (H-DoPS),G H(E),and have been obtained through an appropriate data redaction procedure.All the details this analysis are reported in Appendix A.Subsequently,a comparative evaluation of the re-sults obtained for the all various samples will provided in the fol-lowing,and conclusive,section.4.1.NaAlH4inﬁltrated into ACF25The IINS result for sample(I),i.e.,NaAlH4inﬁltrated into ACF25, is shown in Fig.1and directly compared to equivalent spectra from bulk NaAlH4[15,25]and Na3AlH6[25],both measured at low-tem-perature on the same TOSCA-II instrument.In these two references detailed assignment schemes of both bulk sodium alanate com-pounds are also provided,in full agreement with the ab-initio study by Ke and Tanaka[26].For this reason the mentioned band assignments will not be repeated here.Just by inspecting Fig.1,a comparison between bulk NaAlH4and sample(I)looks straightfor-ward:some phonon bands are shifted after the inﬁltration process, while all the bands are broadened and smoothed,becoming almost structureless.The following observations can be made in detail. Being more accurate,one can note that:(a)the Al–H stretching frequencies(at about217and225meV)slightly increase in the inﬁltrated sample;(b)the AlH4libration frequencies(43.4–69.4meV)stronglydecrease in the melt-inﬁltrated sample;(c)the Al–H–Na bending and the H–Al–H scissoring modes(at74.4and111.6meV,respectively)are almost unaffected.In addition,the band broadening can be quantiﬁed as an extra full-width-at-half-maximum(FWHM)ranging from18.8meV(lat-tice phonon band),to17.1meV(librational band),to30.3meV (bending band)and,ﬁnally,to25.4meV(scissoring band).All these results are considered to be compatible with the typical crys-tal-size effects,where the AlHÀ4tetrahedra located in the external part of an alanate nano-particle are affected by the interaction with the carbon scaffold more strongly than those contained in the core of the particle itself.As for the possible presence of Na3AlH6(or even,but much less likely,of some NaH),noﬁnal conclusion can be drawn at this stage,even though the presence of a modest quan-tity of Na3AlH6appears to be compatible with our neutron data. The IINS spectrum of Na3AlH6is reported in Fig.1,and NaH has been studied in detail in Ref.[27].While the spectrum of NaH exhibits only two strong optical bands(i.e.,transverse and longitu-dinal)between65meV and120meV,basically overlapping the NaAlH4bending mode region,that of Na3AlH6shows an intense band(namely,Al–H valence modes),ranging between130meV and200meV.This interval is particularly important in our case since it exactly overlaps the extra-intensity found in the IINS spec-trum of samples(I),which is totally absent in bulk NaAlH4.4.2.NH3BH3impregnated into MCM41silicaThe neutron spectrum of NH3BH3impregnated into MCM41sil-ica,once subtracted of the small MCM41component,has been compared to a corresponding measurement,always performed on TOSCA-II[28,29],on a bulk NH3BH3sample(with isotopically enriched11B)kept at T=20K.The two measurements are reported in Fig.2,where in both cases the backscattering and forward scat-tering spectra have been summed together so to increase the counting statistics.Before discussing the actual effect of the silica scaffolding on NH3BH3,it is important to understand the nature of the IINS bands visible in Fig.2.For a complete assignment of the vibrational bands of the low-temperature(i.e.orthorhombic) ammonia borane phase,the readership can consult Refs.[30,31]. In the following we report only a rough scheme of the main spec-tral ranges concerning the fundamental vibrational bands:(1)a low frequency region(19–62meV)which contains the lat-tice phonon modes;(2)a medium-low spectral region(87–112meV)containing theB–N stretching modes;(3)an intermediate region(112–161meV)which contains theBH3deformations;(4)a medium-high spectral region(161–211meV)where theNH3deformations are observed;Table2Experimental conditions of the IINS measurements on samples(II)and(IV)performed on IN4C,including:monochromator type,temperature T,counting time s,total sample mass M,and proton concentration(molar)c[H].For samples(II)-a and(IV)-b,d,bulk hydrides and carbonﬁbers(both asﬁne powders)have been mechanically mixed before the IINS measurements.Label Sample Monochrom.T(K)s(h)M(g)c[H](%)(II)-a Inf.LiBH4+Mg(BH4)2+IRH33Cu(220)15.04±0.018.810.9135.92 (II)-b Bulk LiBH4+Mg(BH4)2+IRH33Cu(220)15.04±0.0113.000.9542.79 (II)-c IRH33Cu(220)15.04±0.0120.650.590.00 (IV)-a Impr.MgH2+ACF25Cu(220)15.03±0.019.37 2.5317.00 (IV)-b Bulk MgH2+ACF25Cu(220)15.03±0.017.27 2.4715.55 (IV)-c Impr.MgH2+ACF25PG(006)15.03±0.0111.44 2.5317.00 (IV)-d Bulk MgH2+ACF25PG(006)15.03±0.01 5.01 2.4715.5594 D.Colognesi et al./Journal of Alloys and Compounds538(2012)91–99(5)a high frequency region(273–310meV)containing the B–Hstretching modes;(6)a very high frequency region(384–422meV)containing theN–H stretching modes.However,two points have to be stressed concerning the afore-mentioned assignment obtained through Raman scattering at T=88K.First,IINS on TOSCA-II,due to the well-known Sachs–Tell-er mass tensor effects[32],is not sensitive in this system to bands located at energies higher than180meV,so the H stretching modes are not at all visible in neutron spectra and are not reported in Fig.2.Second,the presence of overtones and combinations in IINS spectra follows very different rules with respect to Raman measurements,so it is also important to consider Ref.[33],where NH3BH3is both simulated and measured by inelastic neutron scat-tering between6and124meV,unfortunately with an energy res-olution not as high as the TOSCA-II one.Nevertheless,the authors of that study were conﬁdent enough to rule out the presence of overtones and combinations at least for E<124meV.Going back to ammonia borane impregnated into MCM41silica,one sees that the effect of MCM41on NH3BH3seems indeed very modest as far as proton vibrational dynamics is concerned.However,some real differences in the lattice phonon bands below45meV(i.e.,acoustic or optical)are visible,as expected since the lattice periodicity is partially disrupted by MCM41[34,35].4.3.LiBH4+Mg(BH4)2inﬁltrated into IRH33carbonThe equimolar solid mixture of lithium borohydride and mag-nesium borohydride is a relatively new system,being proposed by Zhan-Zhao Fan et al.in2010[36],and not much is known about its structure at low temperature,not to mention its lattice and vibrational dynamics.However,from the very recent diffraction studies by Gil Bardajíet al.[37]and Hagemann et al.[38],it seems reasonable to suppose that at the temperature of our IINS measure-ments(i.e.,at about T=15K),Mg(BH4)2appears in its a phase (hexagonal,space group P61)and LiBH4with an orthorhombic structure(space group Pnma,labeled o-LiBH4).For this reason in the rest of the subsection we will pay attention to the dynamic properties of the two separate components,i.e.,o-LiBH4and a-Mg(BH4)2,even though we are well aware that it may be too sim-ple to assume that solid solution properties are simply obtained from a linear combination of those belonging to their components.IINS measurements on bulk o-LiBH4at low temperature(T=5K) have been performed by Hartman et al.[39]making use of a com-pletely isotopic sample(i.e.,7Li and11B)and,subsequently with an improved resolution,by Borgschulte et al.[40]from the same kind of sample at T=15K.From the latter data sets[40,41],employing the procedure sketched in the appendix,we have been able to ex-tract a high resolution estimate of the G H(E)in LiBH4,which has been subsequently altered through a convolution procedure so to match the same energy resolution as that obtained on IN4C.Final results are plotted in Fig.3as EÀ1G H(E).As for pure bulk a-Mg(BH4)2,only IINS data from Ref.[38](apparently taken at low temperature,T’20K)are currently available.However,the experimental conditions(especially those connected to the(Q,E) kinematic path)were not clearly stated in the text,so,unlike in the LiBH4case,no rigorous data treatment has been attempted. The raw experimental spectrum has been just assumed to be approximately proportional to EÀ1G H(E)(after a simple correction for the Bose phonon population factor),neglecting both instrumen-tal background and multiphonon contamination corrections,and has been reported in Fig.3.As a result,one can observe two main facts:(1)LiBH4+Mg(BH4)2inﬁltrated into IRH33and bulk LiBH4+Mg(BH4)2spectra look very similar in all the spectral range 5meV<E<80meV,even though some small differences are clearly detectable.These are certainly larger than the statistical uncertainty of the experimental data(the statisti-cal error bars in Fig.3are of the same size of the line thick-ness),but are homogeneously spread all over the spectra,so it is likely that they have been originated during the data reduction procedure(e.g.,via background subtraction)and do not have a clear physical meaning.(2)Making use of the o-LiBH4and the a-Mg(BH4)2aforemen-tioned data,it is possible to understand the origin of the two bands in the higher frequency part of the spectra of LiBH4+Mg(BH4)2,namely that placed between43and 61meV(A),and that located between61and78meV(B).The former peak,(A),is mainly connected to LiBH4,even though slightly blue-shifted,and represents the rigid libra-tions of the[BH4]Àgroup in this compound[39].The latterD.Colognesi et al./Journal of Alloys and Compounds538(2012)91–9995。

树脂材料作文模板英语版

树脂材料作文模板英语版英文回答：Introduction:Resin materials are synthetic polymers that have a wide range of applications in various industries. They are known for their versatility, durability, and resistance to environmental factors. This essay provides an overview of resin materials, discusses their properties, applications, and environmental implications.Properties of Resin Materials:Resin materials exhibit unique properties that make them suitable for a diverse range of applications. Some of the key properties include:High strength and durability。

Resistance to corrosion, abrasion, and impact。

Lightweight and easy to mold。

Excellent electrical and thermal insulation properties。

Resistance to moisture and chemicals。

Applications of Resin Materials:The versatility of resin materials makes them suitable for a wide variety of applications. Some of the most common applications include:Construction: adhesives, coatings, and structural components。

环氧树脂英文作文

环氧树脂英文作文Epoxy resin is a versatile and widely used material in various industries. It is known for its excellent adhesive properties, high strength, and resistance to chemicals and heat. In the construction industry, epoxy resin is often used for bonding materials such as concrete, metal, and wood. Its strong adhesive properties ensure a durable and long-lasting bond that can withstand heavy loads and extreme conditions.In the automotive industry, epoxy resin is used for various applications, such as coating and sealing electronic components, manufacturing composite parts, and repairing damaged parts. Its ability to resist chemicals and heat makes it an ideal choice for protecting sensitive electronic components from environmental factors and ensuring their proper functioning.Epoxy resin is also widely used in the art and crafts industry. Artists and craftsmen use epoxy resin forcreating beautiful and unique pieces of jewelry, sculptures, and artwork. Its clear and glossy finish adds a touch of elegance to the final product, making it highly desirable among art enthusiasts.Moreover, epoxy resin is commonly used in the manufacturing of electrical and electronic components. Its excellent insulating properties make it an ideal choice for encapsulating and protecting delicate electronic circuits from moisture, dust, and other contaminants. This ensures the reliability and longevity of electronic devices, evenin harsh environments.Furthermore, epoxy resin is extensively used in the marine industry for boat building and repair. Its high resistance to water, chemicals, and UV rays makes it an excellent choice for protecting boats from corrosion and damage caused by constant exposure to water and sunlight. Additionally, epoxy resin is used for laminating and reinforcing fiberglass, providing strength and rigidity to the boat's structure.In conclusion, epoxy resin is a versatile material that finds applications in various industries, including construction, automotive, art and crafts, electronics, and marine. Its unique properties make it a popular choice for bonding, sealing, protecting, and enhancing a wide range of products and materials. Whether it's creating a stunning piece of artwork or ensuring the durability of electronic devices, epoxy resin continues to play a vital role in modern industries.。

海因环氧树脂氧化铝复合材料的性能研究

目前，国内高压开关行业主要使用双酚 A 型、双酚 F 型等传统的环氧树脂作为绝缘材料，但其存在黏度大、固化后玻璃化的温度不高等缺点。国内外学者对新型环氧树脂合成进行了大量研究，合成了不同结构、不同类型和性能各异的新型环氧树脂，例如，含硅环氧树脂、含磷环氧树脂、含氮环氧树脂等。海因环氧树脂是一种含非芳香族氮、杂环胺结构的新型环氧树脂，具有黏度低、浸润性和黏结性优良的特点［3］，其乙内酰脲的杂环结构赋予
天峰化工实业有限公司。氧化铝：α-氧化铝，平均直径为
40～50 μm，中铝研究院有限公司。
CH3 CH3 O CH2 CH CH2 N
O N CH2
O
O CH2 CH CH2 CH CH2 CH3
O
图 1 海因型环氧树脂结构
2.2 样品的制备方法取 100 份环氧树脂分别加入 65 份固化剂和 320 份氧
树脂高绝缘性、耐电弧、抗腐蚀性、高热稳定性等优点［4］，是一种较为理想的绝缘材料。本文选取海因环氧树脂和氧化铝来制备复合材料，并研究复合材料的各项性能，旨在提高绝缘件的综合性能。
2 试样制备及试验方法
2.1 原材料
海因型环氧树脂：MHR-154，湖北锡太化工有限公
司，单体结构如图 1 所示。固化剂：甲基四氢苯酐，西安
1 研究背景
绝缘件作为气体绝缘金属封闭开关（GIS）中的核心零部件，有支撑主导体和隔离气室等作用，其性能决定着 GIS 稳定和电网安全。环氧树脂因具有低成本、易加工的优点以及良好的机械、电气性能而被广泛应用于 GIS 中［1-2］。单纯的环氧树脂通常难以满足使用要求，往往通过添加氧化铝、二氧化硅等填料制成复合材料，以提环氧树脂的电气、机械性能。随着 GIS 向超高电压、小型化方向发展，对环氧材料的性能要求也越来越高。

环氧树脂论文

1 绪论 (3)1.1环氧树脂的简介 (3)1.1.1环氧树脂的发明历史 (3)1.1.2环氧树脂在中国的发展状况 (4)1.1.3研究环氧树脂的意义 (4)1.2环氧树脂的性质及用途 (5)1.2.1环氧树脂的特性 (5)1.2.2环氧树脂的分类、结构及性能（1）环氧树脂的分类 (6)1.2.3环氧树脂的用途 (7)1.3 国内生产消费现状及市场预测 (9)1.3.1国内生产现状 (9)1.3.2国内市场消费现状 (10)1.3.3国内市场分析及预测 (11)1.4 国外生产消费现状及市场预测 (13)1.4.1国外生产现状 (13)1.4.2国外市场消费现状 (13)1.4.3国外市场分析及预测 (15)1.5 低分子量环氧树脂的生产工艺 (15)1.6 本项目设计依据 (21)1.7 建厂规模及产品规格 (21)1.7.1建厂规模 (21)1.7.2产品规格 (21)2 生产原理及工艺流程 (22)2.1 低分子量环氧树脂的反应机理 (22)2.2 双酚A 型环氧树脂生产工艺流程 (24)2.2.1双酚A 型环氧树脂生产工艺流程的选择 (24)2.2.2双酚A 型环氧树脂主要原料 (25)2.2.3双酚A 型环氧树脂生产工艺流程 (26)2.3 生产过程主要操作条件及控制 (27)3 物料衡算与能量衡算 (28)3.1 物料衡算 (28)3.1.1物料衡算的相关知识 (28)3.1.2配比及计算 (29)3.1.3反应釜 (30)3.1.4脱水釜 (32)3.1.5过滤器 (33)3.1.6脱苯釜 (34)3.1.7后处理工序 (34)3.2 能量衡算 (35)3.2.1溶解工序 (35)3.2.2反应工序 (36)3.2.3脱水工序 (39)3.2.4精制工序 (41)4 生产设备的计算与选型 (42)4.1 主要设备工艺尺寸的计算与选型 (42)4.1.1溶解釜的选型 (42)4.1.2反应釜的选型 (45)4.1.3回收环氧氯丙烷冷凝器选型 (48)4.1.4中间贮槽的选型 (50)4.1.5其它设备的选型 (52)4.2 设备一览表 (53)5 环境保护、劳动安全与工业卫生 (54)5.1 环境保护 (54)5.1.1该项目环保设计依据和标准 (54)5.1.2排放污染物成分、排放量及治理方案 (55)5.2 劳动安全、工业卫生与消防 (56)5.2.1编制依据 (56)5.2.2不安全因素及职业危害 (56)5.2.3安全及措施 (58)6 经济效益分析 (58)6.1 原料主要技术规格、供应及消耗定额 (58)6.1.1原料规格及用量 (58)6.1.2原料、能量消耗定额 (58)6.2 车间编制及定员 (59)6.3 项目投资估算 (59)6.3.1项目的投资估算依据 (59)6.3.2投资估算情况 (59)6.4 产品成本分析 (60)6.4.1成本分析依据 (60)6.4.2生产成本估算 (60)6.5 经济分析效益估算 (60)6.5.1经济效益估算 (60)6.5.2投资回收期估算 (61)总结 (61)主要参考文献 (62)致谢 (64)1 绪论1.1环氧树脂的简介1.1.1环氧树脂的发明历史环氧树脂的发明曾经历了相当长的时期。

阻燃降解环氧树脂的研究现状的英文

阻燃降解环氧树脂的研究现状的英文The current research status of flame-retardant and degradable epoxy resins is an area of significant interest in the field of materials science and engineering. Epoxy resins are widely used in various industries due to their excellent mechanical properties, chemical resistance, and adhesive strength. However, the flammability of these resins poses a serious safety concern, necessitating the development of flame-retardant and degradable epoxy resins.In recent years, significant progress has been made in the development of flame-retardant and degradable epoxy resins. A variety of flame retardants, including phosphorus-based, halogen-based, and inorganic flame retardants, have been investigated for their effectiveness in improving the fire resistance of epoxy resins. Among these, phosphorus-based flame retardants have attracted particular attention due to their excellent flame-retardant performance and low toxicity.In addition to flame retardants, biodegradable epoxy resins have also been developed to address the issue of waste disposal. These resins can be degraded under certain conditions, such as exposure to microorganisms or UV light, reducing their environmental impact. Biodegradable epoxy resins are typically based on renewable resources, such as vegetable oils or biobased monomers, which are derived from sustainable sources.The research on flame-retardant and degradable epoxy resins has focused on several key areas. One important aspect is the development of new flame retardants that can effectively improve the fire resistance of epoxy resins while maintaining their mechanical properties and processability. Another focus is on the design of novel degradation mechanisms that allow epoxy resins to degrade under specific conditions, such as exposure to microorganisms or UV light.Moreover, the integration of flame retardants and biodegradability into epoxy resins requires careful consideration of their compatibility and interactions. Thisinvolves studying the effects of flame retardants on the curing behavior, mechanical properties, and degradationrate of epoxy resins. Additionally, the stability and durability of flame-retardant and degradable epoxy resins under various environmental conditions need to be evaluated.In terms of applications, flame-retardant anddegradable epoxy resins have potential uses in a wide range of industries. They can be used in the electronics industry for the manufacture of flame-retardant circuit boards and insulation materials. In the construction industry, these resins can be employed in the development of fire-resistant coatings and flooring materials. Additionally, flame-retardant and degradable epoxy resins may find applications in the automotive, aerospace, and marine industries, where high-performance materials with excellent fire resistance and environmental compatibility are in demand.In conclusion, the research status of flame-retardant and degradable epoxy resins is promising. Significant progress has been made in the development of new flame retardants and degradation mechanisms, and the integrationof these features into epoxy resins is an active area of research. Future studies will focus on optimizing the performance of flame-retardant and degradable epoxy resins, exploring their potential applications, and addressing challenges related to compatibility, stability, and durability.。

复合材料英文文献

复合材料英文文献Composite materials are engineered to combine the best properties of different materials, creating a new material that is stronger, lighter, and more durable than its individual components.These innovative materials are widely used in various industries, from aerospace where they reduce weight and increase fuel efficiency, to construction where they enhance structural integrity and longevity.The versatility of composite materials lies in their ability to be tailored to specific applications. By varying the composition and arrangement of the constituent materials, engineers can optimize the material for strength, stiffness, or resistance to environmental factors.Recent advancements in nanotechnology have further expanded the capabilities of composites. The incorporation of nanomaterials into composite structures can significantly improve their mechanical and thermal properties.One of the key challenges in composite material research is the development of effective recycling strategies. As these materials become more prevalent, finding sustainable ways to reuse or recycle them will be crucial to minimize environmental impact.Educational institutions and industries alike are investing in research to explore new composite material applications. This includes everything from improving sports equipment to developing next-generation energy storage systems.In conclusion, composite materials represent asignificant leap forward in material science. Their unique properties and potential for customization make them indispensable in a wide range of applications, driving innovation and enhancing performance across multiple sectors.。

环氧树脂的改性研究进展

环氧树脂的改性研究进展曾莉;杨云峰;周华【摘要】环氧树脂（EP）是一类应用非常广泛的热固性树脂,在国名经济的发展中占有重要地位,本文综述了改性环氧树脂的最新研究状况,概述了环氧树脂的耐热改性、增韧改性以及阻燃性方面的研究进展,并对环氧树脂改性的新方法进行了展望。

%Epoxy resin（EP） was a kind of thermosetting resin and was widely applied,which occupied an important position in the development of economy.The latest research situation of modified epoxy resin was summarized,including the heat resistant modification,toughening modification and flame retardant.The progress in research of modified by epoxy resin on the new method was also discussed.【期刊名称】《广州化工》【年(卷),期】2011(039)022【总页数】3页(P20-21,24)【关键词】环氧树脂;改性;耐热性;增韧;阻燃性【作者】曾莉;杨云峰;周华【作者单位】中北大学理学院,山西太原030051;中北大学理学院,山西太原030051;中北大学理学院,山西太原030051【正文语种】中文【中图分类】TQ637环氧树脂(EP)是一类非常重要的热固性树脂，它是聚合物基复合材料中应用最广泛的基体树脂之一［1］。

加入固化剂固化后的环氧树脂具有良好的物理化学性能，它与材料的表面具有优异的粘接性能，介电性能良好且固化收缩率小，制品尺寸稳定性好，硬度高，柔韧性较好，对碱及大部分溶剂稳定，因而广泛应用于涂料、电子绝缘材料以及先进复合材料中增强材料的树脂基体等各领域，常用作浇注、浸渍、层压料、粘接剂、涂料等用途。

复合材料注塑成型中英文对照外文翻译文献

复合材料注塑成型中英文对照外文翻译文献(文档含英文原文和中文翻译)An experimental study of the water-assisted injection molding ofglass fiber filled poly-butylene-terephthalate(PBT) compositesAbstract：The purpose of this report was to experimentally study the water-assisted injection molding process of poly-butylene-terephthalate(PBT) composites. Experiments were carried out on an 80-ton injection-molding machine equipped with a lab scale water injection system,which included a water pump, a pressure accumulator, a water injection pin, a water tank equipped with a temperature regulator,and a control circuit. The materials included virgin PBT and a 15% glass fiber filled PBT composite, and a plate cavity with a rib across center was used. Various processing variables were examined in terms of their influence on the length of water penetration in molded parts, and mechanical property tests were performed on these parts. X-ray diffraction (XRD) was also used to identify the material andstructural parameters. Finally, a comparison was made between water-assisted and gas-assisted injection molded parts. It was found that the melt fill pressure, melt temperature, and short shot size were the dominant parameters affecting water penetration behavior.Material at the mold-side exhibited a higher degree of crystallinity than that at the water-side. Parts molded by gas also showed a higher degree of crystallinity than those molded by water. Furthermore, the glass fibers near the surface of molded parts were found to be oriented mostly in the flow direction, but oriented substantially more perpendicular to the flow direction with increasing distance from the skin surface.Keywords: Water assisted injection molding; Glass fiber reinforced poly-butylene-terephthalate (PBT) composites; Processing parameters; B. Mechanical properties; Crystallinity; A. Polymer matrix composites;1. IntroductionWater-assisted injection molding technology [1] has proved itself a breakthrough in the manufacture of plastic parts due to its light weight, faster cycle time, and relatively lower resin cost per part. In the water-assisted injection molding process, the mold cavity is partially filled with the polymer melt followed by the injection of water into the core of the polymer melt. A schematic diagram of the water-assisted injection molding process is illustrated in Fig. 1.Water-assisted injection molding can produce parts incorporating both thick and thin sections with less shrink-age and warpage and with a better surface finish, but with a shorter cycle time. The water-assisted injection molding process can also enable greater freedom of design, material savings, weight reduction, and cost savings in terms of tooling and press capacity requirements [2–4]. Typical applications include rods and tubes, and large sheet-like structural parts with a built-in water channel network. On the other hand, despite the advantages associated with the process,the molding window and process control are more critical and difficult since additional processing parameters are involved. Water may also corrode the steel mold, and some materials including thermoplastic composites are difficult to mold successfully. The removal of water after molding is also a challenge for this novel technology. Table 1 lists the advantages and limitations of water-assisted injection molding technology.Fig. 1. Schematic diagram of water-assisted injection molding process.Water assisted injection molding has advantages over its better known competitor process, gas assisted injection molding [5], because it incorporates a shorter cycle time to successfully mold a part due to the higher cooling capacity of water during the molding process. The incompressibility,low cost, and ease of recycling the water makes it an ideal medium for the process. Since water does not dissolve and diffuse into the polymer melts during the molding process, the internal foaming phenomenon [6] that usually occurs in gas-assisted injection molded parts can be eliminated.In addition, water assisted injection molding provides a better capability of molding larger parts with a small residual wall thickness. Table 2 lists a comparison of water and gas assisted injection molding.With increasing demands for materials with improved performance, which may be characterized by the criteria of lower weight, higher strength, and a faster and cheaper production cycle time, the engineering of plastics is a process that cannot be ignored. These plastics include thermoplastic and thermoset polymers. In general, thermoplastic polymers have an advantage over thermoset polymers in popular materials in structural applications.Poly-butylene-terephthalate (PBT) is one of the most frequently used engineering thermoplastic materials, whichis formed by polymerizing 1.4 butylene glycol and DMT together. Fiber-reinforced composite materials have been adapted to improve the mechanical properties of neat plastic materials. Today, short glass fiber reinforced PBT is widely used in electronic, communication and automobile applications. Therefore, the investigation of the processing of fiber-reinforced PBT is becoming increasingly important[7–10].This report was made to experimentally study the waterassisted injection molding process of poly-butylene-terephthalate (PBT) materials. Experiments were carried out on an 80-ton injection-molding machine equipped with a lab scale water injection system, which included a water pump, a pressure accumulator, a water injection pin, a water tank equipped with a temperature regulator, and a control circuit. The materials included a virgin PBT and a 15% glass fiber filled PBT composite, and a plate cavity with a rib across center was used. Various processing variables were examined in terms of their influence on the length of water penetration in molded parts, which included melt temperature, mold temperature, melt filling speed, short-shot size, water pressure, water temperature,water hold and water injection delay time. Mechanical property tests were also performed on these molded parts,and XRD was used to identify the material and structural parameters. Finally, a comparison was made betweenwater-assisted and gas-assisted injection molded parts.Table 12. Experimental procedure2.1. MaterialsThe materials used included a virgin PBT (Grade 1111FB, Nan-Ya Plastic, Taiwan) and a 15% glass fiber filled PBT composite (Grade 1210G3, Nan-Ya Plastic, Taiwan).Table 3 lists the characteristics of the composite materials.2.2. Water injection unitA lab scale water injection unit, which included a water pump, a pressure accumulator, a water injection pin, a water tank equipped with a temperature regulator, and a control circuit, was used for all experiments [3]. An orifice-type water injection pin with two orifices (0.3 mm in diameter) on the sides was used to mold the parts. During the experiments, the control circuit of the water injection unit received a signal from the molding machine and controlled the time and pressure of the injected water. Before injection into the mold cavity, the water was stored in a tank with a temperature regulator for 30 min to sustain an isothermal water temperature.2.3. Molding machine and moldsWater-assisted injection molding experiments were conducted on an 80-ton conventional injection-molding machine with a highest injection rate of 109 cm3/s. A plate cavity with a trapezoidal water channel across the center was used in this study. Fig. 2 shows the dimensions ofthe cavity. The temperature of the mold was regulated by a water-circulating mold temperature control unit. Various processing variables were examined in terms of their influence on the length of water penetration in water channels of molded parts: melt temperature, mold temperature, meltfill pressure, water temperature and pressure, water injection delay time and hold time, and short shot size of the polymer melt. Table 4 lists these processing variables as well as the values used in the experiments.2.4. Gas injection unitIn order to make a comparison of water and gas-assisted injection molded parts, a commercially available gas injection unit (Gas Injection PPC-1000) was used for the gas assisted injection molding experiments. Details of the gas injection unit setup can be found in the Refs. [11–15].The processing conditions used for gas-assisted injection molding were the same as that of water-assisted injection molding (terms in bold in Table 4), with the exception of gas temperature which was set at 25 C.2.5. XRDIn order to analyze the crystal structure within the water-assisted injection-molded parts, wide-angle X-ray diffraction (XRD) with 2D detector analyses in transmission mode were performed with Cu Ka radiation at 40 kV and 40 mA. More specifically, the measurements were performed on the mold-side andwater-side layers of the water-assisted injection-molded parts, with the 2h angle ranging from 7 to 40 . The samples required for these analyses were taken from the center portion of these molded parts. To obtain the desired thickness for the XRD samples, the excess was removed by polishing theTable 3samples on a rotating wheel on a rotating wheel, first with wet silicon carbide papers, then with 300-grade silicon carbide paper, followed by 600- and 1200-grade paper fora better surface smoothness.2.6. Mechanical propertiesTensile strength and bending strength were measured on a tensile tester. Tensile tests were performed on specimens obtained from the water-assisted injection molded parts (see Fig. 3) to evaluate the effect of water temperature on the tensile properties. The dimensions of specimens forthe experiments were 30 mm · 10 mm · 1 mm. Tensile tests were performed in a LLOYD tensiometer according to the ASTM D638M test. A 2.5 kN load cell was used and the crosshead speed was 50 mm/min.Bending tests were also performed at room temperature on water-assisted injection molded parts. The bending specimens were obtained with a die cutter from parts (Fig. 3) subjected to various water temperatures.The dimensions of the specimens were 20 mm · 10 mm · 1 mm. Bending tests were performed in a micro tensile tester according to the ASTM D256 test. A 200 N load cell was used and the crosshead speed was 50 mm/min.2.7. Microscopic observationThe fiber orientation in molded specimens was observed under a scanning electron microscope (Jeol Model 5410).Specimens for observation were cut from parts molded by water-assisted injection molding across the thickness (Fig. 3). They were observed on the cross-section perpendicular to the flow direction. All specimen surfaces were gold sputtered before observation.3. Results and discussionAll experiments were conducted on an 80-ton conventional injection-moldingmachine, with a highest injection rate of 109 cm3/s. A plate cavity with a trapezoidal water channel across the center was used for all experimentsTable 4Fig. 3. Schematically, the positioning of the samples cut from the molded parts for tensile and bending tests and microscopic observations.3.1. Fingerings in molded partsAll molded parts exhibited the water fingering phenomenon at the channel to plate transition areas. In addition,molded glass fiber filled composites showed more severe water fingerings than those of non-filled materials, as shown photographically in Fig. 4. Fingerings usually form when a less dense, less viscous fluid penetrates a denser,more viscous fluid immiscible with it. Consider a sharp two phase interface or zone where density and viscosity change rapidly. The pressure force (P2 P1) on the displaced fluid as a result of a virtual displacement dx of the interface can be described by [16], where U is the characteristic velocity and K is the permeability.If the net pressure force is positive, then any small displacement will be amplified and lead to an instabilityand part fingerings. For the displacement of a dense, viscous fluid (the polymer melt) by a lighter, less viscous one (water), we can have Dl = l1 l2 > 0, and U > 0 [16].In this case, instability and the relevant fingering result when a more viscousfluid is displaced by a less viscous one, since the less viscous fluid has the greater mobility.The results in this study suggest that glass fiber filled composites exhibit a higher tendency for part fingerings. This might be due to the fact that the viscosity difference Dl between water and the filled composites is larger than the difference between water and the non-filled materials. Waterassisted injection molded composites thus exhibit more severe part fingerings.Fig. 4. Photograph of water-assisted injection molded PBT composite part.3.2. Effects of processing parameters on water penetrationVarious processing variables were studied in terms of their influence on the water penetration behavior. Table 4 lists these processing variables as well as the values used in the experiments. To mold the parts, one central processing condition was chosen as a reference (bold term in TableBy changing one of the parameters in each test, we were able to better understand the effect of each parameter on the water penetration behavior of water assisted injection molded composites. After molding, the length of water penetration was measured. Figs. 5–10 show the effects of these processing parameters on the length of water penetration in molded parts, including melt fill pressure, melt temperature, mold temperature, short shot size, water temperature, and water pressure.The experimental results in this study suggest that water penetrates further in virgin PBT than in glass fiber filled PBT composites. This is due to the fact that with the reinforcing glass fibers the composite materials have less volumetric shrinkage during the cooling process. Therefore,they mold parts with a shorter water penetration length.The length of water penetration decreases with the melt fill pressure (Fig. 5). This can be explained by the fact that increasing the melt fill pressure increases the flow resistance inside the mold cavity. It is then more difficult for the water to penetrate into the core of the materials. The length of water penetration decreases accordingly [3].The melt temperature was also found to reduce the water penetration in molded PBT composite parts (Fig. 6). This might be due to the fact that increasing the melt temperature decreases viscosity of the polymer melt.A lower viscosity of the materials helps the water to packthe water channel and increase its void area, instead of penetrating further into theparts [4]. The hollow core ratio at the beginning of the water channel increases and the length of water penetration may thus decrease.Increasing the mold temperature decreases somewhat the length of water penetration in molded parts (Fig. 7).This is due to the fact that increasing the mold temperature decreases the cooling rate as well as the viscosity of the materials. The water then packs the channel and increases its void area near the beginning of the water channel,instead of penetrating further into the parts [3]. Molded parts thus have a shorter water penetration length.Increasing the short shot size decreases the length of water penetration (Fig. 8). In water-assisted injection molding, the mold cavity is partially filled with the polymer melt followed by the injection of water into the core of the polymer melt [4]. Increasing the short shot size of the polymer melt will therefore decrease the length of water penetration in molded parts.For the processing parameters used in the experiments,increasing the water temperature (Fig. 9) or the water pressure(Fig. 10) increases the length of water penetration in molded parts. Increasing the water temperature decreases the cooling rate of the materials and keeps the polymer melt hot for a longer time; the viscosity of the materials decreases accordingly. This will help the water penetratefurther into the core of the parts [3]. Increasing the water pressure also helps the water penetrate into the materials.The length of water penetration thus increases.Finally, the deflection of molded parts, subjected to various processing parameters, was also measured by a profilemeter.The maximum measured deflection is considered as the part warpage. The result in Fig. 11 suggests that the part warpage decreases with the length of water penetration.This is due to the fact that the longer the water penetration,the more the water pressure can pack the polymeric materials against the mold wall. The shrinkage as well as the relevant part warpage decreases accordingly.Fig. 5. Effects of melt fill pressure on the length of water penetration in molded parts.Fig. 6. Effects of melt temperature on the length of water penetration in molded parts.Fig. 9. Effects of water temperature on the length of water penetration in moldedparts.Fig. 7. Effects of mold temperature on the length of water penetration in molded parts.Fig. 8. Effects of short shot size on the length of water penetration inmolded parts.Fig. 10. Effects of water pressure on the length of water penetration inmolded parts.3.3. Crystallinity of molded partsPBT is a semi-crystalline thermoplastic polyester with a high crystallization rate. In the water-assisted injection molding process, crystallization occurs under non-isothermal conditions in which the cooling rate varies with cooling time. Here the effects of various processing parameters(including melt temperature, mold temperature, and water temperature) on the level of crystallinity in molded parts were studied. Measurements were conducted ona wideangle X-ray diffraction (XRD) with 2D detector analyses(as described in Section 2). The measured results in Fig. 12 showed that all materials at the mold-side lay erexhibited a higher degree of crystallinity than those at the water-side layer. The result indicates that the water has a better cooling capacity than the mold during the cooling process. This matches our earlier finding [17] by measuring the in-mold temperature distribution. In addition, the experimental result in Fig. 12c also suggests that the crystallinity of the molded materials generally increases with the water temperature. This is due to the fact that increasing the water temperature decreases the cooling rate of the materials during the cooling process. Molded parts thus exhibited a higher level of crystallinity.On the other hand, to make a comparison of the crysallinity of parts molded by gas and water, gas-assisted injection molding experiments were carried out on the same injection molding machine as that used with water, but equipped with a high-pressure nitrogen gas injection unit [11–15]. The measured results in Fig. 13 suggests that gas-assisted injection molded parts have a higher degree of crystallinity than water-assisted injection mold parts.This is due to the fact that water has a higher cooling capacity and cools down the parts faster than gas. Parts molded by water thus exhibited a lower level of crystallinity than those molded by gas.Fig. 11. Measured warpage of molded parts decreases with the length of waterpenetration.3.4. Mechanical propertiesTensile tests were performed on specimens obtained from the water-assisted injection molded parts to examine the effect of water temperature on the tensile properties.Fig. 14 showed the measured decrease subjected to various water temperatures. As can be observed, both yield strength and the elongational strain at break of water assisted molded PBT materials decrease with the water temperature. On the other hand, bending tests were also performed at room temperature on water-assisted injection molded parts. The measured result in Fig. 15 suggests that the bending strength of molded parts decreases with the water temperature.Increasing the water temperature generally decreases the cooling rate and molds parts with higher level of crystallin-content of free volume and therefore an increasing level of stiffness. However, the experimental results here suggest that the quantitative contribution of crystallinity to PBT’s mechanical properties is negligible, while there is a more important quantitative increase of tensile and bending strength for the PBT materials.The mechanical properties of molded materials are dependent on both the amount and the type of crystalline regions developed during processing.The fact that the ductility of PBT decreases with the degree of crystallinity may indicate that a more crystalline and stiffer PBT developed at a lower cooling rate during processing and did not exhibit higher stress values in tensile tests because of a lack of ductility, and therefore did not behave as strong as expected from their stiffness [18]. Nevertheless,more detailed experiments will be needed for the future works to investigate the morphological parameters of water-assisted injection molded parts and their correlation with the parts’ mechanical properties.3.5. Fiber orientation in molded partsSmall specimens were cut out from the middle of molded parts in order to observe their fiber orientation. The position of the specimen for the fiber orientation observation is as shown in Fig. 3. All specimen surfaces were polished and gold sputtered before observation. Fig. 16 shows the microstructure of the water-assisted injection molded composite parts. The measured result suggests that the fiber orientation distribution in water-assisted injection molded parts is quite different from that of conventional injection ity. As is usually encountered in semi-crystalline thermoplastics,a higher degree of crystallization means a lower molded parts.In conventional injection molded parts, two regions are usually observed: the thin skin and the core. In the skin region near the wall, all fibers are oriented parallel to the injection molding, water-assisted injection molding technology is different in the way the mold is filled. With a conventional injection molding machine, one cycle is characterized by the phases of filling, packing and cooling.In the water-assisted injection molding process, the mold cavity is partially filled with the polymer melt followed by the injection of water into the core of the polymer melt.The novel filling process influences the orientation of fibers and matrix in a part significantly.From Fig. 16, the fiber orientation in water-assisted injection molded parts can be approximately divided intothree zones. In the zone near the mold-side surface where the shear is more severe during the mold filling, fibers are principally parallel. For the zone near the water-side surface,the shear is smaller and the velocity vector greater.In this case, the fiber tends to be positioned more transversely in the direction of injection. At the core, the fibers tend to be oriented more randomly. Generally speaking,the glass fibers near the mold-side surface of molded parts were found to be oriented mostly in the flow direction, and oriented substantially perpendicular to the flow direction with increasing distance from the mold-side surface.Finally, it should be noted that a quantitative comparison of morphology and fiber orientation [21] in waterassisted molded and conventional injection molded parts will be made by our lab in future works.Fig. 16. Fiber orientation across the thickness of water-assisted injection molded PBTcomposites.4. ConclusionsThis report was made to experimentally study the water-assisted injection molding process of poly-butylene-terephthalate(PBT) composites. The following conclusions can be drawn based on the current study.1. Water-assisted injection molded PBT parts exhibit the fingering phenomenon at the channel to plate transition areas. In addition, glass fiber filled composites exhibit more severe water fingerings than those of non-filled materials.2. The experimental results in this study suggest that the length of water penetration in PBT composite materials increases with water pressure and temperature, and decreases with melt fill pressure, melt temperature, and short shot size.3. Part warpage of molded materials decreases with the length of water penetration.4. The level of crystallinity of molded parts increases with the water temperature. Parts molded by water show a lower level of crystallinity than those molded by gas.5. The glass fibers near the surface of molded PBT composite parts were found to be oriented mostly in the flow direction, and oriented substantially perpendicular to the flow direction with increasing distance from the skin surface.玻璃纤维增强复合材料水辅注塑成型的实验研究摘要：本报告的目的是通过实验研究聚对苯二甲酸丁二醇复合材料水辅注塑的成型工艺。

纳米二氧化硅-环氧树脂复合材料的研究现状

纳米SiO2 /EP复合材料的研究进展摘要：综述了环氧树脂/纳米二氧化硅复合材料的研究进展。

主要介绍了环氧树脂/纳米SiO复合材料的制备方法，并对该复合材料的发展提出了自己的看2法。

关键词：环氧树脂；纳米二氧化硅；复合材料Research development of epoxy/silica hybrid nanocompositesAbstract: The paper gives a brief introduction on the development of epoxy/nano-SiO hybrid materials. Here we mainly present the preparation of epoxy/nano-2SiO，and propose some prospects of this composites。

2Key words: Epoxy; nano-SiO；nanocomposite2）为无定型白色粉末（团聚体），是一种无毒、纳米二氧化硅（nano-SiO2无味和无污染的非金属功能材料。

由于其具有较大的比表面积，并且表面存在着羟基，故具有奇异或反常的特性，如表面效应、小尺寸效应、量子尺寸效应及宏观量子隧道效应，因而在橡胶、塑料、胶粘剂和涂料等领域中应用广泛[1-3]。

目前，研究 nano-SiO的制备方法已成为纳米技术领域的一大热点。

2环氧树脂（EP）是一类典型的热固性树脂，在聚合物复合材料中应用最为广泛。

由于 EP 具有优异的粘接性能、力学性能和电绝缘性能，并且收缩率和成本较低，故在胶粘剂、密封胶和涂料等领域中得到广泛应用[4-5]。

但是，EP 固化物因交联度过高而脆性较大，从而限制了其在某些领域中的应用[6]。

因此，在保证 EP 优异性能的前提下，对其进行增韧改性已成为近年来该领域的研究热点。

粒子因存在着表面缺陷和非配对原子多等特点，与聚合物发生Nano-SiO2物理或化学结合的可能性较大，故可用于增强与聚合物基体的界面结合，提高聚合物的承载能力，从而达到增强增韧聚合物的目的。

nature 环氧树脂和复合材料中c-o键的催化断开

nature 环氧树脂和复合材料中c-o键的催化断开环氧树脂和复合材料中的C-O键是一种非常重要的化学键，它们在材料的性能中起着关键的作用。

然而，在某些情况下，需要催化剂来断开这些键，以便进行一些特定的化学反应。

本文将介绍环氧树脂和复合材料中C-O键的催化断开。

首先，让我们来了解一下环氧树脂和复合材料中的C-O键。

环氧树脂是一种重要的高分子材料，具有优异的物理性能和化学性能。

它通常由环氧树脂单体和固化剂组成，其中环氧树脂单体中含有若干个环氧基(-CH2-CHO-)，固化剂则含有若干个活性氢原子。

在反应中，环氧基和活性氢原子发生加成反应，形成C-O键，从而使环氧树脂单体和固化剂发生交联反应，形成三维网络结构。

这种网络结构赋予了环氧树脂材料优异的物理性能和化学性能。

复合材料是由多种不同的材料组成的材料，其中包括基质材料和增强材料。

基质材料通常是一种聚合物，如环氧树脂，而增强材料则可以是玻璃纤维、碳纤维、芳纶纤维等。

在复合材料中，C-O键通常是由基质材料中的环氧树脂单体和增强材料中的表面官能团发生反应形成的。

这种反应可以增强基质材料和增强材料之间的结合力，从而提高复合材料的强度、刚度和耐久性。

然而，在某些情况下，需要催化剂来断开环氧树脂和复合材料中的C-O键，以便进行一些特定的化学反应。

例如，在环氧树脂中加入一定量的酸类催化剂可以促进环氧基与活性氢原子之间的加成反应，从而加速固化过程。

在复合材料中，如果需要将增强材料与基质材料分离开来，可以使用一些特殊的催化剂来断开它们之间的C-O键。

常用的催化剂包括酸类催化剂、碱类催化剂、金属催化剂等。

酸类催化剂可以促进环氧基与活性氢原子之间的加成反应，从而加速固化过程。

碱类催化剂可以使环氧基发生开环反应，从而断开C-O键。

金属催化剂可以通过与环氧基形成配位键来促进开环反应。

这些催化剂在实际应用中都有广泛的应用。

总之，C-O键在环氧树脂和复合材料中起着非常重要的作用。

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/Journal of Reinforced Plastics and Composites/content/30/19/1621The online version of this article can be found at:DOI: 10.1177/07316844114268102011 30: 1621 originally published online 7 November 2011Journal of Reinforced Plastics and Composites N. Venkateshwaran, A. ElayaPerumal and M. S. JagatheeshwaranEffect of fiber length and fiber content on mechanical properties of banana fiber/epoxy compositePublished by: can be found at:Journal of Reinforced Plastics and Composites Additional services and information for/cgi/alerts Email Alerts:/subscriptions Subscriptions: /journalsReprints.nav Reprints:/journalsPermissions.nav Permissions:/content/30/19/1621.refs.html Citations:What is This?- Nov 7, 2011OnlineFirst Version of Record- Dec 16, 2011Version of Record >>ArticleEffect of fiber length and fiber contenton mechanical properties of banana fiber/epoxy compositeN.Venkateshwaran,A.ElayaPerumal and M.S.JagatheeshwaranAbstractThe main factors that influence the properties of composite are fiber length and content.Hence the prediction of optimum fiber length and content becomes important,so that composite can be prepared with best mechanical prop-erties.Experiments are carried out as per ASTM standards to find the mechanical properties namely,tensile strength and modulus,flexural strength and modulus,and impact strength.In addition to mechanical properties,water absorption capacity of the composite is also studied.Further,fractured surface of the specimen are subjected to morphological study using scanning electron microscope.The investigation revealed the suitability of banana fiber as an effective reinforce-ment in epoxy matrix.Keywordspolymer composites,banana fiber,mechanical properties,scanning electron microscopeIntroductionNowadays,polymers are used everywhere in the day-to-day life.Plastics found its way when the need for low weight high strength material became important for various applications.The research in theﬁeld of poly-mer and polymer-based components has gained wide-spread recognition owing to its property;however,its bio-degradability is still a matter of concern.Further, glassﬁber reinforced polymers(GFRP)have become appealing substitutes for aluminum,concrete,and steel due to its high strength-to-weight ratio,ease of handling,and for being corrosion-free.Moreover, they can also be engineered to get the desired proper-ties.1Since large-scale production and fabrication of glassﬁber causes environmental problems and also health hazards,a suitable alternate which is environ-mental friendly is the need of the hour.Naturalﬁbers that are low cost,lightweight and environmental friendly provide an excellent alternative to glassﬁber. Joshi et al.2reviewed the life cycle assessment of natural ﬁber and glassﬁber composite and found that natural ﬁbers are environmentally superior to glassﬁber,and also reduces the polymer content as reinforcement. Schmidt and Beyer,Wotzel et al.,and Corbiere et al.carried out some important works using the natural ﬁbers as reinforcement in polymer matrix for use in automobile parts.Schmit and Beyer3have replaced the glassﬁber polypropylene(PP)with hemp-PP com-posite for auto-insulation application.Wotzel et al.4 have used hemp-epoxy to replace glassﬁber acryloni-trile butadien–styrene(ABS)for usage in auto-side panel.Similarly,Corbiere et al.5replaced glassﬁber PP with Curaua PP for transporting pallet.All these studies revealed that the naturalﬁber based polymer composite has successfully replaced the glassﬁber. Pothan et al.6studied the eﬀect ofﬁber length and con-tent on the mechanical properties of the short banana/ polyester composite.Study shows that30–40mmﬁber length and40%ﬁber loading provides better mechan-ical properties.Idicula et al.7investigated the mechan-ical performance of banana/sisal hybrid composite and Department of Mechanical Engineering,Anna University,Chennai,India.Corresponding author:N.Venkateshwaran,Department of Mechanical Engineering,Anna University,Chennai,IndiaEmail:venkatcad@Journal of Reinforced Plasticsand Composites30(19)1621–1627!The Author(s)2011Reprints and permissions:/journalsPermissions.navDOI:10.1177/0731684411426810the positive hybrid eﬀect for tensile strength was found to be in the ratio of4:1(banana:sisal). Further,the tensile strength of the composite is better when bananaﬁber is used as skin and sisal as core material.Visco-elastic property of the banana/ sisal(1:1ratio)hybrid composite was studied by Idicula et al.8The study shows that sisal/polyester composite has maximum damping behavior and high-est impact strength as compared to banana/polyester and hybrid composite.Sapuan et al.9prepared the composite by reinforcing woven bananaﬁbers with epoxy matrix.Tensile test result showed that the woven kind of reinforcement has better strength and the same was conﬁrmed using Anova technique also. Venkateshwaran and ElayaPerumal10reviewed the various work in theﬁeld of bananaﬁber reinforced with polymer matrix composite with reference to phys-ical properties,structure,and application. Venkateshwaran et al.11studied the eﬀect of hybridi-zation on mechanical and water absorption properties. Investigation revealed that the addition of sisal in bananaﬁber composite upto50%increases the mechanical properties.Sapuan et al.12designed and fabricated the household telephone stand using woven banana fabric and epoxy as resin.Zainudin et al.13studied the thermal stability of banana pseudo-stem(BPS)ﬁlled unplastisized polyvinyl chlo-ride(UPVC)composites using thermo-gravimetric analysis.The study revealed that the incorporation of bananaﬁller decreases the thermal stability of the composite.Zainudin et al.14investigated the eﬀect of bananaﬁller content in the UPVC matrix.The inser-tion ofﬁller increases the modulus of the composite and not the tensile andﬂexural strength.Zainudin et al.15studied the eﬀect of temperature on storage modulus and damping behavior of bananaﬁber rein-forced with UPVC.Uma Devi et al.16studied the mechanical properties of pineapple leafﬁber rein-forced with polyester composite.Study found that optimum mechanical properties are achieved at 30mmﬁber length and30%ﬁber content.Dabade et al.17investigated the eﬀect ofﬁber length and weight ratio on tensile properties of sun hemp and palmyra/polyester composite.The optimumﬁber length and weight ratio were30mm and around 55%,respectively.From the above literatures,it is evident that the ﬁber length and content are the important factors that aﬀect properties of the composite.Hence in this work,the eﬀect ofﬁber length and weight percentage on the mechanical and water absorption properties of the bananaﬁber epoxy composite is investigated. Further,the fractured surface of the composite are subjected to fractography study to evaluate the frac-ture mechanism.ExperimentalFabrication of compositeA molding box made of well-seasoned teak wood of dimensions300Â300Â3mm3is used to make a com-posite specimen.The top,bottom surfaces of the mold and the walls are coated with remover and kept for drying.Fibers of diﬀerent length(5,10,15,and 20mm)and weight percentage(8,12,16,and20)are used along with Epoxy(LY556)and Hardener (HY951)for the preparation of composite.Testing standardsThe tensile strength of the composite was determined using Tinnus Olsen Universal Testing Machine (UTM)as per ASTM D638standard.The test speed was maintained at5mm/min.In this case,ﬁve specimens were tested with variedﬁber length andﬁber weight ratio.The average value of tensile load at breaking point was calculated.Theﬂexural strength was determined using the above-mentioned UTM as per ASTM D790procedure.The test speed was maintained between1.3and1.5mm/min. In this case,ﬁve samples were tested and the average ﬂexural strength was reported.The impact strength of the composite specimen was determined using an Izod impact tester according to ASTM D256 Standards.In this case,ﬁve specimens were tested to obtain the average value.Figures1to5show the eﬀect ofﬁber length and weight content on ten-sile,ﬂexural,and impact properties.Water absorp-tion behavior of banana/epoxy composites in water at room temperature was studied as per ASTM D570to study the kinetics of water absorption. The samples were taken out periodically andFigure1.Effect of fiber length and weight percentage on tensile strength.1622Journal of Reinforced Plastics and Composites30(19)weighed immediately,after wiping out the water from the surface of the sample and using a precise 4-digit balance to ﬁnd out the content of water absorbed.All the samples were dried in an oven until constant weight was reached before immersing again in the water.The percentage of moisture absorption was plotted against time (hours)and are shown in Figures 6–13.Scanning electron microscopeThe fractured surfaces of the specimens were exam-ined directly by scanning electron microscope Hitachi-S3400N.The fractured portions of the sam-ples were cut and gold coated over the surface uni-formly for examination.The accelerating voltage used in this work was 10kV.Figures 14to 17show the fractured surface characteristics of the compositespecimen.Figure 6.Effect of moisture on fiber content;Fiber length –5mm.Figure 3.Effect of fiber length and weight percentage on flexural strength.Figure 2.Effect of fiber length and weight percentage on tensilemodulus.Figure 4.Effect of fiber length and weight percentage on flexuralmodulus.Figure 5.Effect of fiber length and weight percentage on impact strength.Venkateshwaran et al.1623Figure 12.Effect of moisture on fiber length;Fiber wt%–16.Figure 7.Effect of moisture on fiber content;Fiber length –10mm.Figure 11.Effect of moisture on fiber length;Fiber wt%–12.Figure 10.Effect of moisture on fiber length;Fiber wt%–8.Figure 8.Effect of moisture on fiber content;Fiber length –15mm.Figure 9.Effect of moisture on fiber content;Fiber length –20mm.1624Journal of Reinforced Plastics and Composites 30(19)Results and discussion Mechanical propertiesFor the tensile test,composite specimens are made of ﬁbers of diﬀerent length (5,10,15,and 20mm)and weight ratio (8,12,16,and 20)were used to calculate the tensile strength.Figures 1and 2show the eﬀect of ﬁber length and weight ratios on tensile strength and modulus of the composite,respectively.Figure 1shows that the increase in ﬁber length and weight ratio increases the tensile strength and modulus upto 15mm ﬁber length and 12%weight ratio.Further increases cause the properties to decrease because of lower ﬁber–matrix adhesion and the quantity of ﬁber content being more than matrix.From Figures 1and 2,the maximum tensile strength and modulus oftheFigure 14.SEM micrograph of tensile fracturedspecimen.Figure 15.SEM micrograph of fractured specimen under flexuralload.Figure 16.SEM micrograph of fractured specimen under impactload.Figure 17.Micrograph of poorinterface.Figure 13.Effect of moisture on fiber length;Fiber wt%–20.Venkateshwaran et al.1625composite are16.39MPa and0.652GPa,respectively for theﬁber length of5mm and12%weight ratio. Flexural strength and modulus for diﬀerentﬁber lengths(5,10,15,and20mm)and weight ratios(8, 12,16,and20)are shown in Figures3and4,respec-tively.It was found that the maximumﬂexural strength and modulus are57.53MPa and8.92GPa,respectively for theﬁber length of15mm andﬁber weight of16%.The results of the pendulum impact test are shown in Figure 5.As theﬁber weight and length increases impact strength also increases upto16%ﬁber weight ratio and then begin to decrease.The maximum impact strength of 2.25J/m was found for theﬁber length 20mm and16%ﬁber weight.Although the variousﬁber lengths and weight per-centage provides the maximum mechanical properties, from Figures10,12,and14it can be concluded that the optimumﬁber length andﬁber weight percentage is 15mm and16%respectively as the properties variation with15mm and16%are negligible when compared to the maximum mechanical properties provided by diﬀer-entﬁber lengths and weight percentage indicated as above.The mechanical properties provided above are better than coir18and palmyra.19Water absorption studyThe eﬀects ofﬁber length and content on the water absorption study are shown in Figures6–13.Figures 6to9show the eﬀect ofﬁber content on the water absorption property of the banana/epoxy composite. It shows that as theﬁber content increases the moisture uptake of the composite also increases.This is due to the aﬃnity of the bananaﬁber towards the moisture. The maximum moisture absorption for the composite is around5%for all length and weight percentage of composite.Figures10to13show the eﬀect ofﬁber length on the water uptake capability of composite.It indicates that the variation of length(5,10,15,and 20mm)does not have much impact as compared with theﬁber content.The moisture absorption percentage of bananaﬁber/epoxy composite seems to be lesser than hempﬁber20andﬂaxﬁber21composite. Fractography studyMicrographs of fractured tensile,ﬂexural,and impact specimens are shown in Figures14–17.Figure14shows the micrograph of fractured surface of specimen under tensile load.It clearly indicates that the failure is due to ﬁber pull out phenomenon.Figure15shows the frac-tured surface of the specimen under bending load. Micrograph also shows the bending ofﬁbers due to the application of load.Figure16shows the failure of the composite under impact load.Further,it also shows the striation occurring on the matrix surface and the presence of hole due toﬁber pull out.Figure17shows the micrograph of20mmﬁber length and20%ﬁber weight composite specimen.It clearly indicates that the clustering ofﬁbers result in poor interface with matrix,and in turn decreases the mechanical properties of the composite.ConclusionBased on theﬁndings of this investigation the following conclusions can be drawn:.The optimumﬁber length and weight ratio are 15mm and16%,respectively for bananaﬁber/ epoxy composite..Moisture absorption percentage of banana/epoxy composite for all length and weight percentage is around5..Also,the moisture uptake capability of the compos-ite is greatly inﬂuenced byﬁber content than length. .SEM image shows that increasing theﬁber content above16%results in poor interface betweenﬁber and matrix.References1.Houston N and Acosta F.Environmental effect of glassfiber reinforced polymers.In:Proceedings of2007Earth Quake Engineering Symposium for Young Researcher, Seattle,Washington,2007.2.Joshi SV,Drzal LT,Mohanty AK and Arora S.Are nat-ural fiber composites environmentally superior to glass fiber reinforced posite Part A2004;35: 371–376.3.Schmidt WP and Beyer HM.Life cycle study on a naturalfiber reinforced component.In:SAE Technical Paper 982195.SAE Total Life-Cycle Conference,1–3 December,1998,Graz,Austria.4.Wotzel K,Wirth R and Flake R.Life cycle studies onhemp fiber reinforced components and ABS for automo-tive parts.Die Angewandte Makromolekulare Chemie1999;272:121–127.5.Corbiere-Nicollier T,Laban BG and Lundquist.Lifecycleassessment of bio-fibers replacing glass fibers as reinforce-ment in plastics.Resour Conserv Recycl2001;33:267–287.6.Pothan LA,Thomas S and Neelakantan NR.Shortbanana fiber reinforced polyester composites:mechanical, failure and aging characteristics.J Reinf Plast Compos 1997;16:744–765.7.Idicula M,Neelakantan NR and Oommen Z.A study ofthe mechanical properties of randomly oriented short banana and sisal hybrid fibre reinforced polyester compos-ites.J Appl Polym Sci2005;96:1699–1709.1626Journal of Reinforced Plastics and Composites30(19)8.Idicula M,Malhotra SK,Joseph K and Thomas S.Dynamic mechanical analysis of randomly oriented short banana/sisal hybrid fibre reinforced polyester pos Sci Technol2005;65:1077–1085.9.Sapuan SM,Leenie A,Harimi M and Beng YK.Mechanical property analysis of woven banana/epoxy composite.Mater Design2006;27:689–693.10.Venkateshwaran N and ElayaPerumal A.Banana fiberreinforced polymer composite-a review.J Reinf Plast Compos2010;29:2387–2396.11.Venkateshwaran N,ElayaPerumal A,Alavudeen A andThiruchitrambalam M.Mechanical and water absorption behavior of banana/sisal reinforced hybrid composites.Mater Design2011;32:4017–4021.12.Sapuan SM and Maleque MA.Design and fabrication ofnatural woven fabric reinforced epoxy composite for household telephone stand.Mater Design2005;26: 65–71.13.Zainudin ES,Sapuan SM,Abdan K and MohamadMTM.Thermal degradation of banana pseudo-stem fibre reinforced unplastisized polyvinyl chloride compos-ites.Mater Design2009;30:557–562.14.Zainudin ES,Sapuan SM,Abdan K and MohamadMTM.The mechanical performance of banana pseudo-stem reinforced unplastisized polyvinyl chloride compos-ites.Polym Plast Technol Eng2009;48:97–101.15.Zainudin ES,Sapuan SM,Abdan K and MohamadMTM.Dynamic mechanical behaviour of bananapseudo-stem filled unplasticized polyvinyl chloride com-posites.Polym Polym Compos2009;17:55–62.16.Uma Devi L,Bhagawan SS and Sabu Thomas.Mechanical properties of pineapple leaf fiber-reinforced polyester composites.J Appl Polym Sci1997;64: 1739–1748.17.Dabade BM,Ramachandra Reddy G,Rajesham S andUdaya kiran C.Effect of fiber length and fiber weight ratio on tensile properties of sun hemp and palmyra fiber reinforced polyester composites.J Reinf Plast Compos 2006;25:1733–1738.18.Harish S,Peter Michael D,Bensely A,Mohan Lal D andRajadurai A.Mechanical property evaluation of natural fiber coir composite.Mater Characterisation2009;60: 44–49.19.Velmurugan R and Manikandan V.Mechanical proper-ties of palmyra/glass fiber hybrid posite Part-A2009;38:2216–2226.20.Dhakal HN,Zhang ZY and Richardson MOW.Effect ofwater absorption on the mechanical properties of hemp fibre reinforced unsaturated polyester composites.Compos Sci Technol2007;67:1674–1683.21.Alix S,Philippe E,Bessadok A,Lebrun V,Morvan V andMarais S.Effect of chemical treatments on water sorption and mechanical properties of flax fibres.Bioresour Technol2009;100:4742–4749.Venkateshwaran et al.1627。