等规聚丙烯/聚丁烯-1釜内合金的结构与性能

高分子材料的组成、 组分分布及链结构与宏观性能紧密相关. 因此, 分析多组分釜内合金材料的链结构特点与性能之间的关系至关重要. 采用升温淋洗分级的方法对两种采用序贯两段聚合原位合成的等规聚丙烯/聚丁烯-1(iPP/iPB)釜内合金在-30 ℃~140 ℃温度范围进行分级, 采用核磁共振波谱仪、 傅里叶变换红外光谱仪、 差示扫描量热仪和凝胶渗透色谱仪等表征了级分的链结构及序列分布、 热行为、 分子量(M_w)及分子量分布(M_w/M_n)等. 结果表明iPP/iPB合金主要由5种级分组成, 高等规聚丁烯(iPB)为主要组分, 同时含有少量的丁烯-丙烯嵌段共聚物(PB-b-PP)和等规聚丙烯(iPP)等. 随淋洗温度升高, PB-b-PP级分中PP嵌段长度逐渐增加, PB嵌段长度逐渐减小; 在相同的淋洗温度, 合金B的嵌段共聚物级分中PP嵌段较长且结晶较完善; 合金B中iPB组分及嵌段共聚物组分含量较高, 使得合金B具有较高的拉伸强度、 弯曲强度、 优异的抗冲击性能、 较高的维卡软化温度及较快的晶型转变速率.

Structures and Properties of Isotactic Polypropylene/Polybutene-1 In-reactor Alloys

The performance of materials is closely related to the composition， component distribution and molecular chain structure. Therefore， it is vital to analyze the relationship between chain structure and performance of alloys with multiple components. Two novel isotactic polypropylene/polybutene-1 in-reactor alloys（iPP/iPB） synthesized by sequential two-stage polymerization were fractionated by the temperature rising elution fractionation at a temperature ranging from -30 ℃ to 140 ℃. The chain microstructure and sequences distribution， crystallization behavior， molecular weight（M_w） and molecular weight distribution（M_w/M_n） of fractions were characterized by ¹³C NMR， FTIR， DSC， GPC. The results showed that iPP/iPB alloys were mainly composed of five components， including the high isotactic polybutene-1（iPB） as the main component， a small amount of poly（（butene-1）-block-propylene） block copolymer（PB-b-PP）， isotactic polypropylene（iPP）， etc. With the increase of elution temperatures， the length of PP blocks in the PB-b-PP components gradually increased， while that of PB blocks gradually decreased. At the same elution temperature， Alloy B possessed longer PP block in copolymer fractions and exhibited more perfect PP crystal. Alloy B containing higher iPB and PB-b-PP components showed higher tensile strength， flexural strength， excellent impact resistance， higher Vicat softening temperature and faster crystal transformation rate.