Study On The Prosperities Of Trans-1,4-Polyisoprene And Styrene-Butadiene Rubber

Trans-1,4-polyisoprene（TPI） can significantly improve the dynamicperformance of blend vulcanizates under the condition of keepingmechanical properties when blended with general rubbers. This may berelated to its unique crystalline and the chain regularity. In this issue,amorphous styrene-butadiene rubber （SBR） was chosen to blend with TPI.The crystallization characteristic of the TPI was analyzed from tensilecrystallization and temperature crystallization. Physical and dynamicperformances of filled and unfilled TPI/SBR blend were studied from thepoint of TPI s crystallization.TPI of different polymerization are compared and analyzed,FTIRand1HNMR show that bulk polymerization TPI and solutionpolymerization TPI have similar trans-structure content, GPC curvesshow that bulk polymerization TPI have a certain quantity of lowmolecular material, GC-MS further indicate that bulk polymerization TPIcontains more oligomer, this may be related to the post-processing way.DSC test showed that two kinds of TPI appear complete three crystallineform（α、β、γ）, bulk polymerization TPI is mainly β crystalline, solutionpolymerization TPI is mainly γ crystalline, the crystallinity of bulkpolymerization TPI is slightly better than above solution polymerizationTPI. The melting point of solution polymerization TPI which has betterlamellae thickness was significantly higher than bulk polymerization TPI.Tests show that TPI prepared by solution polymerization have greatermechanical performance. So the following experiment all use solutionTPI with butyl benzene rubber.TPI/SBR under different temperature heat preservation differenttime are analyzed by DSC. The results show that the melting pointdecreased and the melting limit increase wide when the temperaturelower about insulation the same time of unfilled TPI/SBR, the enthalpychange at-25℃is the highest, crystallinity is the biggest. Thecrystallization significantly reduced but melting point did not change a lotafter filled with carbon black. As the temperature down,the melting pointdecrease and the melting limit increase wide. When the temperature from0℃dropped to-25℃, the melting limit broadens the most obvious. Tests of different draw ratio unfilled TPI/SBR show that thesample s flex resistance can be significantly improved after pre-stretch,the dynamic fatigue performance of specimen pre-stretched to2timeswas the best. With the pre-stretch ratio increased, the melting temperatureof the sample gradually shifted to higher temperature. FTIR resultsshowed that the sample after pre-stretch appear crystal absorption peaksin1032㎝^-1.The mechanical properties of TPI/SBR filled with carbon black wereimproved significantly. The elongation at break reduced while tensilestrength improved after pre-stretch. After thermal aging, break elongationrate decrease and tensile strength rate almost have no change. DSC showthat the crystallinity of filled TPI/SBR reduced significantly, thecrystallinity of pre-stretch TPI/SBR present irregular changes. The test ofTPI/SBR at different times of pre-tension showed that, the dynamicfatigue performance of specimen pre-stretched3h was improvedsignificantly, the crystallinity increased with pre-stretched time, thesample at different pre-stretched time all appear crystal absorption peaksin1032㎝^-1.