摘要
用不同结构的乙烯基硅烷与聚乙烯进行熔融接枝及水解缩合交联反应，通过对接枝物的结构表征、交联行为以及交联前后结晶性能、高温应力～应变曲线的测定，研究了不同结构的乙烯基硅烷对硅烷与聚乙烯的接枝反应和交联反应的影响。结果表明，不同烷氧基的硅烷在接枝、交联性能上存在较大差异；接枝反应的活性与烷氧取代基的空间位阻效应和电子效应有关；在Ａ１７２接枝情况下，接枝大分子自由基的终止方式在促进接枝和大分子支化方面起着重要的作用；交联反应的速率与烷氧基的水解缩合反应能力有关，而交联程度则取决于硅烷的接枝率。由于交联网络的存在，硅烷交联聚乙烯的高温力学性能显著提高，交联密度决定了其抵抗变形的能力，硅烷接枝交联后，聚乙烯的结晶速率、熔点和结晶度都有不同程度的降低。
The grafting and crosslinking reactions of LDPE with three different vinyl silanes vinyltrimethoxysilane(A171),vinyltriethoxysilane(A151),vinyltri 2 methoxyethoxysilane(A172) were carried out. In the basis of characterization of grafted product and crosslinking behavior, measurements of thermal loading and crystallization behavior before and after crosslinking, the effects of structure of silanes on grafting and crosslinking reactions were investigated. It is found that the degree of grafting of silane onto LDPE varied with the order:A172>A171>A151, which can be expected to be due to the steric effect and electron distribution in double bond, particularly in the case of A172 grafting, the termination pattern of macromolecular radicals played an important rule in promoting both silane grafting and chain branch. Similarly A172 grafted LDPE shows the highest speed and the final degree of crosslinking because of its methoxyethyoxyl group′s reactivity of hydrolysis, whereas A151 grafted LDPE remaines the lowest. The resistance of the vulcanizates to deform in high temperature under loading dependes on the density of crosslinking. As far as crystallization behavior was concerned, the crystallization rate, T m, and X c decreased various, according to the degree of crosslinking.
出处
《高分子材料科学与工程》
EI
CAS
CSCD
北大核心
1999年第4期48-51,共4页
Polymer Materials Science & Engineering
