Preparation and properties of SBS ,kaolinite clay compound and asphalt modified with the compound
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Polymer Degradation and Stability 87 (2005) 309e317 www.elsevier.com/locate/polydegstab
Preparation and properties of styreneebutadieneestyrene copolymer/kaolinite clay compound and asphalt modified with the compound
Abstract Styreneebutadieneestyrene copolymer (SBS)/kaolinite clay (KC) compounds were prepared using a mixing technique. The effects of SBS/KC ratio and mixing temperature on the mechanical properties of the compounds and the distribution of molecular weight of SBS were investigated. The compounds were successfully used to improve the high-temperature storage stability of asphalts as compared with pure SBS modified asphalts. The improvement in high-temperature storage stability could be attributed to the KC in the SBS/KC compounds for it decreased the difference of densities between SBS and asphalt. The effects of KC on the high-temperature storage properties, mechanical properties, dynamic mechanical properties, and morphologies of SBS/KC modified asphalts were studied. The SBS/KC ratio in the compounds had a great effect on the hightemperature storage stability. The modified asphalts were very stable at high temperature when the SBS/KC ratio was around 3. The maximum KC content in the modified asphalts was 2%, and the KC content had slight influence on the mechanical properties of the modified asphalts. The KC could improve the rheological properties of the modified asphalt to some extent. Ó 2004 Elsevier Ltd. All rights reserved.
the material, while the butadiene, the soft block, contributes to the elasticity of SBS. The hard block dispersed in the soft one forms physical crosslinks, a three-dimensional network. At temperatures above the glass transition temperature of the styrene block, the physical crosslinks disappear. Upon cooling, the crosslinks reform, and the strength and elasticity of the SBS are restored. At a given temperature in the range of the glass transition temperatures of both soft block and hard block (ÿ90 C wC90 C) [2], the SBS behaves like an elastomer. SBS can contribute to asphalt strength and elastic properties in a wide range of temperature by blending SBS with asphalt [3,4]. So SBS is one of the most promising modifiers for asphalt. Unfortunately, SBS is destined to separate from the asphalt when stored at high temperature, which is the major obstacle to the
Fig. 1. Morphology of KC.
Some SBS/KC compounds with the SBS/KC ratio of 100/30 were prepared in a HAAKE rheometer at temperatures of 130, 140, 150, 170 and 190 C for 12 min. The values of torque variation with time were recorded. 2.3. Filtration of SBS from SBS/KC compound About 3 g of SBS/KC (100/30) compound mixed using the HAAKE rheometer was immerged in 50 ml solvent of tetrahydrofuran (THF) in a beaker. After being stored for 5 h, the mixture in the beaker was filtered on a low velocity filter paper until the filtered liquid was clear. About 10 ml filtered liquid was laid aside in a clean beaker. After stored in a vacuum oven at the temperature of 30 C for 24 h, the beaker was transferred to a desiccator. Five hours later, the sample (SBS) was scratched from the beaker for the test of molecular weight distribution. 2.4. Molecular weight distribution test At room temperature, 25 mg (weighed accurately) SBS was dissolved in 5 ml THF, then 0.2 ml sample was taken out and injected into testing system at a fixed flow rate of 1 ml/min, where a laser scattering instrument (wave length was 690 nm) was coupled to an HPLC (Waters DAWN EOS, USA). 2.5. Mechanical properties test SBS/KC compound, prepared as given in Section 2.2, was moulded for 8 min at 160 C under pressure of 15 MPa, then transferred to room temperature and moulded for 5 min under a pressure of 10 MPa. Dumbbell specimens were cut and tested using an Instron 4465 universal testing machine at a crosshead speed of
Chunfa Ouyang*, Shifeng Wang, Yong Zhang, Yinxi Zhang
Research Institute of Polymer Materials, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China Received 6 July 2004; received in revised form 25 August 2004; accepted 31 August 2004
* Corresponding author. Tel.: C862154742671; fax: C862154741297. E-mail address: kingkii@sjtu.edu.cn (C. Ouyang). 0141-3910/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymdegradstab.2004.08.014
310
C. Ouyang et al. / Polymer Degradation and Stability 87 (2005) 309e317
application of SBS modified asphalts in paving [5]. To resolve the problem, many measures have been taken, such as reactive blending and adding carbon black [5e10], but the reaction processes in the former cannot be controlled easily and the processing technique in the latter is complicated. Kaolinite clay (KC) is a type of mineral, belonging to the inorganic silicates, and abundant in nature [11]. When added to a bituminous mixture, KC can contribute aggregate with adhesive properties. Meanwhile, KC can improve the high-temperature resistance, aging resistance and wear resistance of an asphalt road [12]. Asphalt modified by SBS, with storage stability at high temperature, was prepared by incorporating carbon black into SBS compounds in our research group [5]. However, there have been few reports about the preparation of the SBS modified asphalt with hightemperature storage stability by using SBS/KC compound till now [13]. In the present work, the preparation and properties of SBS/KC compounds were studied. The effect of KC content on the mechanical properties of SBS/KC compounds was analysed. The molecular distribution of SBS in the compounds mixed at different temperatures was analysed. SBS/KC compound modified asphalts were studied. For comparison, asphalts modified by directly adding SBS and KC were also prepared. The effects of KC on the high-temperature storage stability, mechanical properties and rheological properties of SBS modified asphalts were analysed.
Keywords: SBS; Kaolinite clay; Asphalt; Storage stabil来自百度文库ty
1. Introduction Asphalt has been widely used in road pavement as the binder of aggregate. Unfortunately, high-temperature rutting and low temperature cracking of asphalt cement or coating layer, due to severe temperature susceptibility, limit its further application [1]. Therefore, it is necessary to modify asphalt. Styreneebutadienee styrene tri-block copolymer (SBS) as one of the modifiers of asphalt is a synthetic thermoplastic elastomer. The styrene, referred as the hard block, is usually the dispersed phase, and provides the strength of
Preparation and properties of styreneebutadieneestyrene copolymer/kaolinite clay compound and asphalt modified with the compound
Abstract Styreneebutadieneestyrene copolymer (SBS)/kaolinite clay (KC) compounds were prepared using a mixing technique. The effects of SBS/KC ratio and mixing temperature on the mechanical properties of the compounds and the distribution of molecular weight of SBS were investigated. The compounds were successfully used to improve the high-temperature storage stability of asphalts as compared with pure SBS modified asphalts. The improvement in high-temperature storage stability could be attributed to the KC in the SBS/KC compounds for it decreased the difference of densities between SBS and asphalt. The effects of KC on the high-temperature storage properties, mechanical properties, dynamic mechanical properties, and morphologies of SBS/KC modified asphalts were studied. The SBS/KC ratio in the compounds had a great effect on the hightemperature storage stability. The modified asphalts were very stable at high temperature when the SBS/KC ratio was around 3. The maximum KC content in the modified asphalts was 2%, and the KC content had slight influence on the mechanical properties of the modified asphalts. The KC could improve the rheological properties of the modified asphalt to some extent. Ó 2004 Elsevier Ltd. All rights reserved.
the material, while the butadiene, the soft block, contributes to the elasticity of SBS. The hard block dispersed in the soft one forms physical crosslinks, a three-dimensional network. At temperatures above the glass transition temperature of the styrene block, the physical crosslinks disappear. Upon cooling, the crosslinks reform, and the strength and elasticity of the SBS are restored. At a given temperature in the range of the glass transition temperatures of both soft block and hard block (ÿ90 C wC90 C) [2], the SBS behaves like an elastomer. SBS can contribute to asphalt strength and elastic properties in a wide range of temperature by blending SBS with asphalt [3,4]. So SBS is one of the most promising modifiers for asphalt. Unfortunately, SBS is destined to separate from the asphalt when stored at high temperature, which is the major obstacle to the
Fig. 1. Morphology of KC.
Some SBS/KC compounds with the SBS/KC ratio of 100/30 were prepared in a HAAKE rheometer at temperatures of 130, 140, 150, 170 and 190 C for 12 min. The values of torque variation with time were recorded. 2.3. Filtration of SBS from SBS/KC compound About 3 g of SBS/KC (100/30) compound mixed using the HAAKE rheometer was immerged in 50 ml solvent of tetrahydrofuran (THF) in a beaker. After being stored for 5 h, the mixture in the beaker was filtered on a low velocity filter paper until the filtered liquid was clear. About 10 ml filtered liquid was laid aside in a clean beaker. After stored in a vacuum oven at the temperature of 30 C for 24 h, the beaker was transferred to a desiccator. Five hours later, the sample (SBS) was scratched from the beaker for the test of molecular weight distribution. 2.4. Molecular weight distribution test At room temperature, 25 mg (weighed accurately) SBS was dissolved in 5 ml THF, then 0.2 ml sample was taken out and injected into testing system at a fixed flow rate of 1 ml/min, where a laser scattering instrument (wave length was 690 nm) was coupled to an HPLC (Waters DAWN EOS, USA). 2.5. Mechanical properties test SBS/KC compound, prepared as given in Section 2.2, was moulded for 8 min at 160 C under pressure of 15 MPa, then transferred to room temperature and moulded for 5 min under a pressure of 10 MPa. Dumbbell specimens were cut and tested using an Instron 4465 universal testing machine at a crosshead speed of
Chunfa Ouyang*, Shifeng Wang, Yong Zhang, Yinxi Zhang
Research Institute of Polymer Materials, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China Received 6 July 2004; received in revised form 25 August 2004; accepted 31 August 2004
* Corresponding author. Tel.: C862154742671; fax: C862154741297. E-mail address: kingkii@sjtu.edu.cn (C. Ouyang). 0141-3910/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymdegradstab.2004.08.014
310
C. Ouyang et al. / Polymer Degradation and Stability 87 (2005) 309e317
application of SBS modified asphalts in paving [5]. To resolve the problem, many measures have been taken, such as reactive blending and adding carbon black [5e10], but the reaction processes in the former cannot be controlled easily and the processing technique in the latter is complicated. Kaolinite clay (KC) is a type of mineral, belonging to the inorganic silicates, and abundant in nature [11]. When added to a bituminous mixture, KC can contribute aggregate with adhesive properties. Meanwhile, KC can improve the high-temperature resistance, aging resistance and wear resistance of an asphalt road [12]. Asphalt modified by SBS, with storage stability at high temperature, was prepared by incorporating carbon black into SBS compounds in our research group [5]. However, there have been few reports about the preparation of the SBS modified asphalt with hightemperature storage stability by using SBS/KC compound till now [13]. In the present work, the preparation and properties of SBS/KC compounds were studied. The effect of KC content on the mechanical properties of SBS/KC compounds was analysed. The molecular distribution of SBS in the compounds mixed at different temperatures was analysed. SBS/KC compound modified asphalts were studied. For comparison, asphalts modified by directly adding SBS and KC were also prepared. The effects of KC on the high-temperature storage stability, mechanical properties and rheological properties of SBS modified asphalts were analysed.
Keywords: SBS; Kaolinite clay; Asphalt; Storage stabil来自百度文库ty
1. Introduction Asphalt has been widely used in road pavement as the binder of aggregate. Unfortunately, high-temperature rutting and low temperature cracking of asphalt cement or coating layer, due to severe temperature susceptibility, limit its further application [1]. Therefore, it is necessary to modify asphalt. Styreneebutadienee styrene tri-block copolymer (SBS) as one of the modifiers of asphalt is a synthetic thermoplastic elastomer. The styrene, referred as the hard block, is usually the dispersed phase, and provides the strength of