碳纳米管 CNTS

第8卷　第19期　2008年10月167121819(2008)1925487204　科　学　技　术　与　工　程Science Technol ogy and Engineering　Vol 18　No 119　Oct 12008Ζ　2008　Sci 1Tech 1Engng 1一般工业技术成形工艺对碳纳米管/聚苯胺导电性能影响曹　东(广州中医药大学信息技术学院广州510006)摘　要　探讨一种新型阵列式碳纳米管/聚苯胺材料的复合方法,采用CVD 法制备多壁阵列式碳纳米管,采用原位聚合法将其与苯胺单体结合,制备出聚苯胺/碳纳米管复合材料,研究了氧化剂与苯胺单体比例、碳纳米管加入时间、搅拌速度等工艺因素对复合材料导电性能的影响。

试验结果表明当氧化剂与苯胺单体比例为1/2、碳纳米管最初加入时电导率达到最大,搅拌速度影响很小。

关键词　碳纳米管 复合材料 聚苯胺 导电性中图法分类号　T B383; 文献标志码　A2008年6月3日收到作者简介:曹　东(1975—),男,博士,广州中医药大学信息技术学院。

E 2mail:caodong9@ 。

Since carbon nanotubes (CNTs )were discovered,extensive research in this field has rap idly e merged .The s pecial p r operties of CNTs have attracted more and more researchers πinterest .Polyaniline (P AN I )beca me one potential candi 2date t o synthesize such CNTs composites because it has excellent ther mal and envir onmental stability as com 2pared t o other conducting poly mers .It has a s pecialstructure that can increase the binding f orce bet w een the P AN I and CNTs,which leads t o CNTs diss olving well .Ne w polyaniline /nanotube composites was repor 2ted[1,2].W e als o synthesized the aligned multi 2wallcarbon nanotubes (AMWCNTs )/P AN I composite using AMWCNTs[3—5].The influencial fact ors on the AMWNTs/P AN I composite electrical conductivity are datailed .The oxi 2dant p r oporti on,the ti m e during which poly merizati on AMWCNTs were added and the stirring s peed were in 2vestigated .It shows that the use of AMWNTs materialleads t o the f or mati on of a genuine composite material with enhanced electr onic p r operties .1　Exper i m en t a l1.1　Prepara ti on of A WM CNTs 1.1.1　MaterialsFerr ocene (99%)and di m ethylbenzene (99%)were purchased fr o m the Shanghai Reagent Company .A r 2and H 2were obtained fr om the Nanchang Special Gas Company .1.1.2　AWMCNTs synthesisThe AWMCNTs used in this experi m ent were fab 2ricated in a tubular resistance furnace by the che m icalvapor depositi on (CVD )method [6,7].First the furnacewas vacuu med,and then A r 2was input int o the furnace as the p r otective gas and H 2as the reducing agent .D i m ethylbenzene was used as a carbon s ource and fer 2r ocene as a catalyst and then the m ixture of D i m ethyl 2benzene with ferr ocene was intr oduced int o the fur 2nace .The reacti on te mperature was kep t at app r oxi 2mately 800℃f or 30m inutes .Then the AWMCNTswere acquired.Fig .1　Sche matic illustrati on of the equi pmentof fabricating the nanotub1—gas inlet,2—gas outlet,3—furnace,4—quartz glass 5—quartz tube,6—sealed st opp le,7—material inlet1.2　Trea t m en t of A WM CNTsThe AWMCNTs were dis persed by adding the dis 2persant —duodenary alkyl sulfuric natriu m (C 12H 25S O 3Na )obtained fr om the Shanghai Reagent Compa 2ny,and then treated ultras onically f or 12hours [8].1.3　Fabr i ca ti on of A WM CNTs/PAN I co m posite 1.3.1　MaterialsAniline (99%),muriatic acid (37%)and per oxy 2sulfuric acid a m ine (99%)were purchased fr om the Shanghai Reagent Company .The distilled water andthe treated AWMCNTs we fabricated on site .1.3.2　Composite synthesisThe “in 2stiu ”method was used in synthesizing the composite .Per oxysulfuric acid a m ine acted as the oxidant in the poly merizati on [9].The muriatic acid was added t o the aniline in one beaker .The oxidant with the muriatic acid was sl owly dr opped int o the aniline s oluti on while a stirrer m ixed it .Meanwhile the treated AWMCNTs were added int o the beaker .After finishing dr opp ing,the resultant composite was i m mersed in di 2lute muriatic acid f or 24hours,and then repeatedly fil 2tered using distilled water until the s oluti on πs pH value equaled seven .Finally,it was dried in an oven at60℃f or 12hours .1.4　I n stru m en t a ti on sThe conductivity of the composite was tested using a S DY —4f our poles conductivity instru ment fr om Bei 2jing J iangzhong Company.Fig .2Sche matic of composite synthesis 1—D r opper,2—stirrer,3—beaker2　Results and D iscussi onTable 1shows the influence of the p r oporti on of the oxidant t o aniline on the conductivity .It shows the conductivity increases as the p r oporti on becomes grea 2ter and reaches the maxi m u m at 1/2.W hen the p r o 2porti on increases further,the conductivity will de 2crease .This is because when the p r oporti on is less than 1/2the number of active oxidants is s mall s o it p r oduces larger molecular weight polyaniline in a l ong molecular chain .The electric chargesmove more easily in a l ong chain than in a short one .So the conductivity is better .But when the p r oporti on exceeds 1/2,the active oxidants are s o nu mer ous that results in the chain of the polyaniline are oxidized by then and the chain πs conjugated structure is destr oyed .Consequent 2ly,the conductivity decreases .So the 1/2p r oporti on is the op ti m ized value .Table 1　The i n fluence of the proporti on of ox i dan t to an ili n ePr oporti on (oxidant/aniline )1/41/31/21/13/2Conductivity (s /c m )2.02.76.43.02.5Table 2shows the influence of the stirring s peed ontheconductivity .Thes peeddoesn πtaffectpolyaniline πs attachment t o the AWMCNTs or its gr owth,s o the conductivity net w ork doesn πt change .8845科　学　技　术　与　工　程8卷Table2　The i n fluence of the sti rr i n g speedStirring s peed(r/m inute)78300600 Conductivity(s/c m)8.18.08.2Table3shows the influence of change in the ti m e over which the poly merizati on of AWMCNTs occurs. W hen AWMCNTs exist during the poly merizati on peri2 od,because the AWMCNTsπtube wall are cores,the s mall P AN I attach t o the AWMCNTs and gr ow on the cores.I n this way,the P AN I gr o w s omething si m ilar t o a tube.W hen they gr ow enough they meet and for m one big P AN I/AWMCNTs conductivity net w ork.The electric charges transfer in this net w ork easily p r oviding good conductivity.W hen the AWMCNTs were not add2 ed until later,the cores are the P AN I itself or another i m purity first and P AN I gr ows on the cores.Then the AWMCNTs were added,other P AN I gr ow on the AWMCNTs cores.This causes the net w ork t o be inho2 mogeneous,hence the conductivity is poor.The exper2 i m ental results show that delayed additi on means the conductivity worse,because the net w ork homogeneity is worse.But,as seen in table3,it is worst without AWMCNTs.This is because the net w ork canπt be for med without AWMCNTs.Table3The i n fluence of the po i n t dur i n gpoly m er i za ti on a t wh i ch A WM CNTs were addedTi m e(m inute)01030W ithout AWMCNTs Conductivity(s/c m)8.88.157.5 6.393　Conclusi on sThe synthesis of a AWMCNTs/P AN I composite was comp leted.The influence fact ors on the composite conductivity have studied.The synthesis by an in situ poly merizati on p r ocess leads t o effective site2selective interacti ons bet w een the chain of the P AN I and the AWMCNTs.It increases the binding force bet w een the P AN I and AWMCNTs,which contributes t o a good conductivity net w ork in the composite.It all ows elec2 tric charges t o transfer easily resulting in enhanced e2 lectr onic p r operties bet w een the t o components.The results str ongly suggest that when the p r opor2 ti on of the oxidant and aniline is1/2the conductivity is best.It als o shows that the conductivity will increase when the AWMCNTs are added before poly merizati on begins.It de monstrated clearly that the stirring s peed has no influence on the conductivity.References1　J infen N,B inghua Y Ye Y Devel opment of poly mer/CNTS electric composites.Engineering Plastics App licati on,2007;(7):85—872　Daobao C,Zhongp ing C.Preparati on and electr oche m ical p r operties of carbon nanotube/nanocrystalline Ti O22polyaniline comp lex fil m electr ode.Journal of Che m ical I ndustry and Engineering,2007;58(6):1568—15743　Cao D,Zeng X S,Zhou Z H.Synthesis of the naotubes/P AN I com2 posite.Nanoscience&Technol ogy,2004;(1):40—424　Cao D.The basic research of nanotube/polyaniline composite.Nan2 chang University,Master thesis,20045　Zeng X S,Cao D,L iW T.Research and p reparati on of carbon nano2 composite materials.Fiber Reinf orced Plastics/Composites,2004;(2):13—166　Zeng X S,Cao D,Zhou Z H.I nvestigati on on p r oducti on of aligned array multi2wall carbon nanotubes on a large scale.Journal of Syn2 thetic Crystals,2003;(2):175—1787　Zhou Z H,Cao D,Zeng X S.Technol ogic research on the gr owth of aligned carbon nanotubes.Journal of Nanchang University(Engi2 neering&Technol ogy),2003;25:(3)22—238　Cao D,Zeng X S,Zhou Z H.D is persant′s influence on the aligned carbon nanotubes dis persal.Technol ogy&Ne w Pr ocess,2003;(10):48—49984519期曹　东:成形工艺对碳纳米管/聚苯胺导电性能影响　0945科　学　技　术　与　工　程8卷I nfluences Factors on the A li gned M ulti2wa ll CarbonNanotubes/Polyan ili n e Com positeπs Electr i ca l Conducti v ityCAO Dong(I nf or mati on Technol ogy College,Guangzhou University of Chinese Medicine,Guangzhou510006,P1R1China)[Abstract]　The synthesis of ne w aligned multi2wall carbon nanotubes(AMWNTs)/P AN I material was studied. The AMWNTs was fabricated by CVD method first.Then,by an“in situππpoly merizati on p r ocess aniline with AWMCNTs ARE compounded and AMWNTs/P AN I material was gotten.The effects on the compositeπs electrical conductivity of p r ocessing fact ors,such as the oxidant p r oporti on,the durati on poly merizati on AWMCNTs were add2 ed and the stirring s peed,were investigated.The data str ongly shows that the oxidant p r oporti on and the ti m e dur2 ing poly merizati on AWMCNTs were added influence the conductivity nevertheless the stirring s peed is fe w.[Key words]　carbon nanotubes composite polyaniline conductivity(上接第5483页)Ana lysis of Con tact Stress about Extrusi on of Fru itXU Zheng,W E IL i2bo(College of W ater Conservancy&A rchitectural Engineering,Shihezi University,Shihezi832003,P1R1China)[Abstract]　The Max well viscoelastic bodies using contact theoretic knowledge and the Finite Ele ment p r ogra m design knowledge t o analyze theory the extrusi on contact of fruit are adop t.Some rules are summarized.These have definite meaning t o mechanis m da mage because of contacting during the p r ocess in harvesting and st oring.[Key words]　fruit contact stress viscoelastic。