相对分子质量及其分布对稀土顺丁橡胶性能的影响

Effects of relative molecular mass and its distribution on properties of rare-earth catalyst-based cis-1,4-polybutadiene rubber

研究了5种不同相对分子质量及其分布的稀土顺丁橡胶（NdBR）的性能。结果表明，NdBR生胶和混炼胶的门尼黏度随相对分子质量的增加而升高；窄相对分子质量分布（多分散指数小于3．00）NdBR的生胶门尼黏度略高于与其相对分子质量相近而分布较宽的NdBR。相对分子质量对NdBR的正硫化时闯影响不大，但最小转矩和最大转矩有随相对分子质量的增加而增大之趋势。生胶相对分子质量较低的NdBR，其硫化胶的300％定伸应力和拉伸强度较低，生热值较高，耐磨性能下降，滚动阻力升高。生胶门尼黏度为39～49的NdBR，其硫化胶的综合性能良好。填充适量操作油可以提高硫化胶的物理机械性能。窄相对分子质量分布NdBR硫化胶的300％定伸应力、拉伸强度、扯断伸长率、回弹性、永久变形、耐磨性以及滚动阻力等都优于相对分子质量相近而分布较宽的NdBR。

The properties of five kinds of rareearth catalyst-based cis-1, 4-polybutadiene rubber （NdBR） with different relative molecular mass and its distribution were studied. The results showed that the Mooney viscosity of the raw and mixed stock of NdBR increased with the increase of relative molecular mass. The Mooney viscosity of NdBR with narrower relative molecular mass distribution （polydispersity index less than 3.00） was slightly higher than that of wider one with similar relative molecular mass. The effect of relative molecular mass on optimum cure time was not unobvious, but minimum and maximum torque increased with its increase. The modulus at 300% , tensile strength and abrasion resistance were lower, but the heat build-up and rolling resistance higher of their vulcanizates when the relative molecular mass of NdBR was lower. The balanced properties of NdBR vulcanizates were favorable when their raw rubber Mooney viscosity was from 39 to 49. Adding suitable quantity of processing oil could enhance mechanical properties of NdBR vulcanizates. The modulus at 300% , tensile strength, elongation at break, resilience, heat buildup, permanent set, abrasion resistance as well as rolling resistance of NdBR with narrower relative molecular mass distribution were superior to those of wider ones with similar relative molecular mass.