主链结构对聚丙烯球形粒子中苯乙烯固相接枝聚合的影响

Effect of Main-Chain Structure on Solid-Phase Grafting Polymerization of Styrene in Spherical Polypropylene Granules

以DQ型催化剂催化丙烯均聚和丙烯 /少量乙烯无规共聚得到的两种多细孔球形聚烯烃粒子为母体 ,进行了自由基引发苯乙烯固相接枝共聚 ,考察了反应条件对两种粒子中接枝聚合规律的影响 ,发现共聚物 (PPR )母体中的苯乙烯接枝共聚比均聚物 (PP )有更高的接枝率和接枝效率。与PP的接枝产物相比 ,具有相同接枝率的PPR接枝产物的熔点和熔融焓下降幅度较大。研究表明 ,聚丙烯的链结构对其固相接枝共聚规律和接枝产物性质有直接的影响 ,少量共聚单体的存在有利于提高接枝效率 。

Solid-phase grafting polymerizations of styrene onto two kinds of sp herical polyolefin granules were studied in detail.The polyolefins were isotact ic polypropylene homopolymer (PP) and propylene-ethylene copolymer (PPR) each s y nthesized by using a spherical high-yield catalyst.Effects of various reaction parameters on grafting reactions were investigated.Reaction on copolymer (PPR) showed higher graft percentage (GP) and graft efficiency (GE) than th at on homopo lymer (PP).When at same graft percentage (GP) graft products from copolymer (PP R) showed lower melting points (T m) and melting enthalpy (ΔH m) than that from h omopolymer (PP).The fact indicated main-chain structure directly affected reac t ion behaviors and product properties.Introducing a small amount of comonomer in polypropylene enhanced graft efficiency and changed distribution of branching c hains.