摘要
在以 n-BuLi(正丁基锂)为引发剂,2G(二乙二醇二甲醚)为结构调节剂,环己烷为溶剂的丁二烯聚合体系中,用 SiCl_4为偶合剂,研究了不同的偶合条件对聚合物的偶合效率 x、支化度 g、特性粘数[η]、分子量分布 D、微观结构、玻璃化温度 T_g 及流变行为和屈服强度σy 的影响。结果表明,当 SiCl_4/n-BuLi(mol 比)约为0.3时,偶合效率、支化度、[η]、表观粘度η_a 和σ_y 出现最大值;偶合反应对聚合物的微观结构、T_g 无影响;偶合的聚合物在低剪切速率下有较高的η_a 和表观活化能 E_(?),在高剪切速率下有较低的η_a 和 E_(?),并加宽了分子量分布,提高了σ_(y),从而可改善聚合物的冷流性与加工性。
Synthesis of star medium vinyl polybutadiene was carried out by polymeri-
zation of butadiene in cyclohexane using n-BuLi as initiator,diglycoldimethyl-
ether(2G)as structure regulator, and SiCl_4 as coupling agent.Effects of different
coupling reaction conditions on the coupling efficiency of polymer,branching
degree,intrinsic viscosity,molecular weight distribution,microstructure,glass tran-
sition temperature,rheological properties and yield strength of the polymer were investigated.Experimental results show that,when SiCl_4/n-BuLi(mol ratio)is
around 0.3,the coupling efficiency,branching degree,intrinsic viscosity,flow
viscosity and yield strength of the polymer all reach their maxima.The coupling
reaction time,temperature,basic molecular weight,and dosage of coupling agent
have no effect on the microstructure and glass transition temperature of the
polymer.The coupled polymers have respectively higher and lower flow viscosity
and activation energy at lower and higher shear rates.The molecular weight dis-
tribution of the coupled polymer is broadened and yield strength is increased as
compared with the base polymer.It indicates that the cold flow properties as
well as the processability of the star-shaped medium vinyl content polybutadiene
are greatly improved.
出处
《石油化工》
CAS
CSCD
北大核心
1990年第9期596-601,共6页
Petrochemical Technology
