用γ-氯丙基三甲氧基硅烷端基改性星形溶聚丁苯橡胶

Terminal modification of star-shaped solution polymerized styrene-butadiene rubber with 3-chloropropyl trimethoxy silane

以自制多官能度有机锂为引发剂,采用负离子聚合法制备了星形溶聚丁苯橡胶(SSBR),然后加入异丙醇氧锂作为解缔剂,降低体系黏度,再加入封端剂γ-氯丙基三甲氧基硅烷进行封端反应,得到端基带有三甲氧基丙基硅烷基团的改性SSBR。用核磁共振对产物进行了表征,考察了解缔剂用量、封端剂用量、封端时间以及数均分子量对SSBR封端率的影响。结果表明,解缔剂可明显降低聚合体系黏度,当SSBR的数均分子量为9.4×104、解缔剂与引发活性中心数的摩尔比为1.5、封端剂与活性中心数的摩尔比为1.5以及封端反应进行60 min时,封端率由未解缔直接封端的10.7%提高到64.1%。解缔后高封端率SSBR硫化胶与未封端和未解缔低封端率SSBR硫化胶相比,其炭黑-白炭黑填料粒子分散更均匀,且拉伸强度和300%定伸应力提高,永久变形明显降低,具有0℃损耗因子高和60℃损耗因子低的特点。

Star-shaped solution polymerized sty- rene-butadiene rubber （SSBR） was synthesized by anionic polymerization with multifunctional lithium as initiator, and then dissociative agent lithium secpropoxide was added to decrease the solution viscosity, after that the capping agent 3-chloropropyl trimethoxy silane was added to react with the living polymer chain ends to obtain alkoxysilane-capped starshaped SSBR. The characterization of the products was conducted with nuclear magnetic resonance, and the effects of amounts of dissociative agent, capping agent and capping reaction time and number-average molecular weight on capping rate were investigated. The results showed that the dissociative agent could reduce the viscosity of solution of star-shaped SSBR. The capping rate raised from 10. 7% for undissociated but directly capped SSBR to 64. 1% when number-average molecular weight was 9.4 ×10 4, both the mole ratios of dissociative agent to initiating active center and capping agent to active center were 1.5, and end-capping reaction time was 60 min. Compared with uncapped or undissociated, low capping rate star-shaped SSBR vulcanizates, the dissociated, high capping rate star-shaped SSBR vulcanizates exhibited better carbon black-silica filler dispersion, higher tensile strength and modulus at 300%, lower permanent set, higher loss factor at 0 ℃ and lower loss factor at 60 ℃.