聚丙烯与马来酸酐和苯乙烯在超临界CO_2中的双组分接枝

Dual Grafting of MAH/styrene onto Polypropylene Using Supercritical CO_(2) Fluid

在超临界CO2 介质中 ,颗粒状的聚丙烯与马来酸酐、苯乙烯通过自由基接枝聚合生成了聚丙烯 g (马来酸酐 苯乙烯 )。探讨了双组分单体的摩尔比 ,溶胀温度和时间 ,反应压力和时间等对接枝率的影响。结果表明 ,苯乙烯作为一种共聚单体能够明显提高双组分的接枝率。在 5 0℃和 10MPa压力下溶胀 2h后 ,升温至 12 5℃、17MPa时反应 4h ,双组分接枝产物的最大接枝率为 10 5 8% ,比在同样条件下聚丙烯接枝马来酸酐的接枝率大 1倍。用FTIR和DSC表征了接枝共聚物的结构和热性能。聚丙烯支链中引入苯乙烯的结构单元 ,使产物的Tm由 15 8℃降低到 15

Free-radical dual grafting of maleic anhydride(MAH) and styrene(St) onto granular polypropylene(PP) using supercritical CO_(2) as a solvent and swelling agent has been studied and PP-g-(MAH-St) prepared. The effect of molar ratio of monomers, swelling temperature and time, reaction time and pressure on the grafting density are discussed. It is found that the St as a co-monomer in the grafting reaction system could (significantly) enhance the grafting density of PP for MAH and St on PP. The maximum grafting density for PP-g-(MAH-St) in supercritical CO_(2) fluid under optimal reaction conditions was 10.58%, two times that for PP-g-MAH. The process is simpler than regular graft polymerization processes. The structures and properties of the graft copolymers were characterized by FTIR and DSC. The results indicate that styrene branch chains reduces the T_(m) of PP from 158 ℃ to 154 ℃.