动态硫化EPDM/PP共混型热塑性弹性体的老化效应

Study on heat aging effect of EPDM/PP TPV

研究了自制和商业化的动态硫化EPDM/PP共混型热塑性弹性体(TPV)老化和重复加工性能。结果表明,EPDM/PPTPV的力学性能和弹性不随老化而变差,但老化后TPV的Instron毛细管流变仪挤出样条表面变得粗糙,熔体黏度稍有增大,经过热辊重新熔融返炼后,流动性能基本上可以恢复到老化前的状态。采用橡胶加工性能分析仪分析EPDM/PPTPV的热老化机理,热老化过程不仅使分散相橡胶粒子发生物理粘连,而且使橡胶粒子和连续相PP间产生一定程度的化学结合,产生了化学联结的橡胶粒子联结体,这种联结体在高剪切条件下可以被破坏。自制的TPV具有优良的反复加工性能,经热辊180℃连续塑炼1h,其各项性能基本上保持不变。

The heat aging and repeat processing behaviors of EPDM/PP TPV were investigated.The result showed that, the retainability of mechanical properties and elastic property were pretty high after heat aging,but the extrude surface of the samples became coarse and the viscosity of the blends became high after heat aging.However,it was worth noticing that the flow property including viscosity of the blends and the surface of the extrude samples could be restored by backmixing. The heat aging mechanism of thermoplastic vulcanizates was studied by RPA. The results showed that under heat aging condition, rubber phase not only coalesced and agglomerated but also took chemical interact with continuous phase polypropylene in some extent, which came into being the coupling effect,the coupling effect could be destroyed under high shear condition.The TPV made in our lab also had excellent repeat processing behavior,all the properties of the blends almost remained the original state after repeated processing at the temperature of 180 ℃with processing time range 0～60 min.