聚丙烯的熔融自由基支化及反应过程

Melt Radical Branching and Reaction Course of Polypropylene

以转矩流变仪为反应器,对聚丙烯熔融自由基支化反应及其反应过程进行研究,考察了引发剂DHBP用量及反应时间对PP支化产物熔体特性的影响.结果表明：过量的引发剂会导致PP的降解,使PP的熔体流动速率升高,熔体强度降低;而引发剂浓度过低则会使熔融支化反应进行不充分,产物熔体没有较好的应变硬化效果,熔体强度也较低.DHBP的用量需控制在0.05 自0.15份的范围内,以0.1份为宜.以扭矩-时间曲线为参照,在不同反应时间点进行取样分析,研究了PP熔融支化的反应历程.当反应时间控制在125 ～ 185 s内时,PP产物的熔体强度较高.

A research on molten polypropylene＇ s branching reaction,as well as its reaction course,was implemented in a torque rheometer. The modified polypropylene was fabricated, and its melt performances, related to the initiator DHBP＇ s dosages and reaction times,were investigated at the same time. The results indicated that a high DHBP concentration could lead to PP＇s degradation, thus making high MFR and low melt strength. Conversely, a low content made a deficient reaction that result in bad melt strain-hardening and low melt strength. Initiator＇ s dosages should be limited in the range of 0.05 to 0. 15 phr. The best dosage of DHBP was 0. 1 phr. Depending on the torque-time curve, some samples with different reaction times were chosen to analyze the course of PP melt branching reaction. When the times were in the range of 125 to 185 s, the production could obtain higher melt strength than the raw PP.