Synthesis And Hydrogenation For Styrene-isoprene-styrene Copolymers With Different Micro-structures

This article studies the regulatory ability of some new structural modifiers,which are N,N-dimethyltetrahydrofurfuyl amine(DMTH FA),Ethyl tetrahydrofurfuryl ether(ETE),Ethyl tetrahydrofurfuryl et her/tetrahydrofuran(ETE/THF),Ethyl tetrahydrofurfuryl ether/sodium dodecylbenzene sulfonate(ETE/SDBS)on micro-structure of poly is oprene anionic polymerization system.Based on this,SEPS with hi gh content of propylene units were obtained by hydrogenation of SI S with nickel naphthenate and triisobutylaluminum as catalysts.According to this research both DMTHFA and ETE are efficient modifiers.The polyisoprene 3,4-structure content can be controlled form 7.4%to 64.1%,with R in between 0.08 and 1.27 when using DMTHFA as modifier at 50? for reaction;When using ETE as modifier at 50? for reaction,with R in between 0.21 and 1.46,the polyisoprene 3,4-structure content can be controlled form 11%to 54%.When using ETE/THF compound modifier under the same R value,the modifying ability is better than when ETE is used solely,but weaker than the sum of ETE and THF used individually as modifiers.ETE/SDBS compound modifier has a better modifying ability than ETE modifier,when ETE content is relatively low,the composite effect is rather apparent,the polyisoprene 3,4-structure produced is almost equal to that is obtained when same dosage of those 2 modifier are used solely.The modifying ability of DMTHFA,ETE,ETE/THF,ETE/SDBS decreases when temperature drops,DMTHA is more stable than ETE..In SIS hydrogenation test,nickel naphthenate and triisobutylaluminum were used as hydrogenation catalysts.Experiment found that following n(Al):n(Ni)increasing,the hydrogenation degree of SIS increased firstly and then decreased,and when n(Al):n(ni)=3.8,the hydrogenation of SEPS reached its peak.In the same conditions,the hydrogenation degree of SIS increased with more catalysts added.In polymerization process,the introduction of structural modifiers has a negative effect on hydrogenation(THFA>ETE>THF),with more introduced,the hydrogenation decreases.By changing the concentration of bond in glue,we found that the optimum concentration for hydrogenation is around 1000mmol/L.By comparing aging at low temperature and long time to aging at high temperature and short time we found the latter one has higher catalytic activity.The nickel naphthenate concentration shoud be controlled at around 0.01%for nickel mass fraction during the aging process in order to improve catalytic activity.The SEPS and SIS were characterized by FI-IR and 1HNMR.The results showed that the hydrogenation capacity of SIS polyisoprene was 1,2-structure>3,4 structure>1,4-structure and Benzene zing wasn't hydrogenated.With the 3,4-structure content and styrene content increasing,SIS and SEPS will have comparatively higher tensile strength,shore hardness and lower elongation at break.Increased hydrogenation results in reduced tensile strength,increased elongation at break and reduced shore hardness.An increase in the 3,4-structure will lead to an increase in the SIS and SEPS melt index.Styrene content increases,molecular weight increases,increased hydrogenation will lead to SIS and SEPS melt index decreaseing.