摘要
以甲基环己基二甲氧基硅烷(C-donor)、二环戊基二甲氧基硅烷(D-donor)、二异丙基二甲氧基硅烷(DIP)和二异丁基二甲氧基硅烷(DIB)4种外给电子体,对聚丙烯DQC球形催化剂进行了预接触时间液相本体聚合研究。采用GPC,DSC,13C NMR等方法对聚合物的热性能、相对分子质量分布及分子序列结构进行表征。实验结果表明,聚合时延长DQC催化剂与助催化剂三乙基铝和外给电子体的预接触时间,催化剂的聚合活性降低;得到聚合物的等规指数升高,熔体流动指数下降,细粉含量增加。表征结果显示,聚合时延长DQC催化剂的预接触时间,得到的聚合物的Mn和Mw均下降,相对分子质量分布变窄;聚合物的熔融温度、熔融焓,结晶温度、结晶焓等热性能数值均有不同程度的提高;聚合物的全同立构三单元组mm和五单元组mmmm均增加,说明预接触时间延长可提高聚合物的立构规整度。
The effects of the pre-contact time of the DQC catalyst, triethyl aluminium co- catalyst and external electron donors on the bulk polymerization of propylene were studied with four separate external electron donors, namely cyclohexyl（dimethoxy）methylsilane（C- donor）, dicyclopentyldimethoxysilane（D-donor）, diisopropyldimethoxysilane（DIP）and diisobutyldimethoxysilane（DIB）. The polypropylene products were characterized by means of GPC, DSC and 13C NMR. The results indicated that, with the increase of the pre-contact time, both the activity of the DQC catalyst and the melt indexes of the products decreased, while the isotactic indexes and the fine powder contents of the products increased. It was shown that the increase of the pre- contact time resulted in the products featuring a narrower molecular weight distribution and decreased the number-average molecular weight and weight-average molecular weight of the products. The corresponding melting temperature, melting enthalpy, crystallization temperature and crystallization enthalpy of the products increased with the increase of the pre-contact time. The 13C NMR results showed that the contents of both the stereoregular triad mm sequence and the pentad mmmm sequence in the products increased with the increase of the pre-contact time.
出处
《石油化工》
CAS
CSCD
北大核心
2016年第12期1468-1474,共7页
Petrochemical Technology
关键词
预接触时间
外给电子体
DQC球形催化剂
聚丙烯
丙烯液相本体聚合
pre-contact time
external electron donor
DQC catalyst
polypropylene
propyleneliquid phase bulk polymerization
