摘要
考察了酚醛树脂 (Novolak)的增容作用对聚甲醛 (POM) /丁腈橡胶 (NBR)共混物的韧性、结晶形态和亚微相态的影响 .实验结果表明 ,POM与 NBR不相容 ,直接共混不能提高 POM的韧性 ;添加 Novolak后 ,当 NBR质量分数为 4 0 %时共混物发生“脆 -韧”转变 .POM/NBR共混物中 POM球晶尺寸大 ,易形成应力集中点 ,导致增韧效果不佳 ;Novolak可通过与 POM的分子链间相互作用 ,改变 POM分子链固有的规程和排列方式 ,使球晶显著减小 .亚微相态显示 ,POM/NBR呈现“海 -岛”结构相态 ,NBR在基体中分散性很差 ;添加 Novolak可提高 NBR在基体中的分散性 ;当 NBR质量分数达到 4 0 %时 ,NBR在基体中呈现带状网络结构 .网带结构能够终止受外力作用而在基体中产生的银纹和剪切屈服 ,增加了共混物的破裂能 。
Compatibilizing effect of novolak on toughness, crystallite, and morphology of polyacetal(POM) and nitrile butadiene(NBR) blends were investigated. It was found the POM and NBR were immiscible system, and the compatibilization of POM and NBR could be improved by addition of Novolak. As a result, Izod impact strength increased remarkably. The crystallite morphology of the blends under polarized light microscopy demonstrated that the size of spherulites of POM was so large as to increase the brittleness of blends. The size of spherulites of POM could be sharply reduced by mixing with Novolak, which suggested that the inner stress concentration in blends be diminished. POM/NBR blends exhibited a “sea island” morphology, where NBR was the dispersed phase “sea” and POM was continuous phase “island”. The morphology of POM/NBR/novolak(mass ratio 60/40/5) blends showed that there was not a “sea island” structure but a physical elastomer network. The elastomer network impeded the growth of craze and promoted the shear deformation of POM matrix. As a result, a large amount of impact energy could be absorbed and the super toughness was thus obtained.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2001年第4期673-677,共5页
Chemical Journal of Chinese Universities
基金
北京市科技新星计划资助
