NR/PP和NR-g-PMMA/PP两种热塑性弹性体的结构与性能

Morphology and properties of thermoplastic elastomer based on NR/PP blends and NR-g-PMMA/PP blends

采用动态硫化法制备了天然橡胶(NR)/聚丙烯(PP)和NR-甲基丙烯酸甲酯接枝共聚物(NR-g-PMMA)/PP两种共混型热塑性弹性体。采用扫描电镜(SEM)、差示量热扫描法(DSC)、热重分析法(TGA)以及物理机械性能测试对样品进行了表征,对比了两种弹性体的结构与性能。结果表明,两种共混物均呈现热塑性弹性体典型的“海-岛”相结构,NR-g-PMMA分散相的粒径更大且更容易发生团聚现象;当PP质量分数为30%时,NR-g-PMMA/PP的拉伸强度和100%定伸应力明显高于NR/PP。DSC分析表明NR-g-PMMA/PP中PP的结晶度高于NR/PP。TGA的结果表明,两种热塑性弹性体的降解均分为两个阶段,第一个阶段为NR和NR-g-PMMA的降解;第二个阶段为PP的降解,两种弹性体的热稳定性相差不大。

This works investigated the morphology and properties of two kinds of thermoplastic elastomers (TPEs) prepared by the dynamic vulcanization technique.One was the blends of natural rubber (NR) and isotactic polypropylene(PP),and the other was the blends of NR grafted with poly(methyl methacrylate)(NR- g -PMMA) and PP.The morphology of the TPEs examined by scanning electron microscopy disclosed that NR or NR- g -PMMA particles dispersed in PP matrix,and the particle sizes in NR- g -PMMA/PP blends were larger than that in NR/PP at the same content of PP.When the content of PP was 30%,NR- g -PMMA/PP blends had higher tensile strength and tensile stress at 100% than that of NR/PP because of higher crystallinity of PP in NR- g -PMMA/PP blends.The mogravimetry analysis showed that the thermal degradation of the TPEs could be divided into two stages:one was the degradation of NR or NR- g -PMMA and the other was PP.There was little difference in thermal stability between two kinds of TPEs.