【摘要】 针对苯乙烯(St)单体对不同聚集态结构聚丙烯(PP)的扩散聚合行为进行了研究.结果表明,共聚PP由于乙丙共聚无定形区的存在,能够为St单体的扩散提供更大的自由体积,故St单体扩散速率更快,达到聚苯乙烯(PS)扩散饱和值更大,而且共聚PP颗粒中PS纳米微球粒径也从均聚PP的115 nm增大到150~200 nm.由于PP颗粒中的聚集态结构不同,在PP颗粒中的PS分布将从均聚PP的"M"型分布变成共聚PP的"n"型分布.扩散到PP颗粒内部的St对PP的接枝作用不仅能防止PS纳米微球在成型加工过程时的单纯聚并,而且可使材料的拉伸强度、模量及断裂伸长率明显提高,体现了PS刚性粒子对PP的增强增韧作用.更多还原

【Abstract】 Diffusion and polymerization behavior of styrene(St)in homo-polypropylene and co-polypropylene(PP)were studied.The results show that the presence of ethylene-propylene copolymerization region in co-polypropylene can provide more free volume for the diffusion of St,so the diffusion rate of St is faster and the diffusion saturation of PS is higher.Moreover,the size of polystyrene(PS)nanoparticles in co-polypropylene increased from 115 nm to 150—200 nm.Since the aggregation states of PP pellets are different,the PS distribution in PP pellets will change from the"M"shape curve of homo-polypropylene to the"n"shape curve of co-polypropylene.Owing to the chemical grafting of St in PP pellets,PS nanoparticles were aggregating instead of coalescing during processing and the tensile strength,elastic modulus and breaking elongation were improved significantly,reflects the role of strengthening and toughening by PS rigid particles.更多还原