提高转化率对丁腈橡胶性能的影响

Effect of increasing conversion on performance of acrylonitrile-butadiene rubber

研究了丁腈橡胶合成过程中聚合时间对转化率和聚合速率的影响,考察了提高转化率对丁腈橡胶生胶的门尼黏度、凝胶含量、结合丙烯腈量、相对分子质量及其分布,胶乳的黏度和机械稳定性及硫化胶力学性能等的影响。结果表明,转化率从71%左右升高到75%以上,反应时间约需延长2.5 h,反应后期聚合速率变缓。与转化率为71%左右时相比,转化率达75%以上时所制得丁腈橡胶生胶的门尼黏度和凝胶含量明显增加,结合丙烯腈量降低,相对分子质量增大,分子量分布变宽;胶乳黏度增大,机械稳定性下降;硫化胶的拉伸强度和300%定伸应力提高,扯断伸长率则降低。

The effect of polymerization time on the monomer conversion and polymerization rate in the synthesis of acrylonitrile-butadiene rubber were studied,and the effects of increasing conversion on Mooney viscosity of raw rubber,bound acrylonitrile content,gel content,latex viscosity,relative molecular mass and its distribution,mechanical properties of vulcanizates were investigated.The results showed that when the conversion increased from 71% to 75%,the polymerization time needed to be prolonged by 2.5 h,and the polymerization rate slowed down during the late polymerization.Compared to the rubber with conversion 71%,the raw rubber Mooney viscosity and gel content for the rubber with conversion 75% increased evidently,the bound acrylonitrile content decreased,the relative molecular mass,polydispersion index and latex viscosity raised,the latex mechanical stability reduced,the tensile strength and modulus at 300% of vulcanizates enhanced,but the elongation at break lowered.