摘要
采用两种单茂钛催化剂体系Cp*T i(OC6H4C l)3/MAO(Cp*为η5-五甲基环戊烯基,MAO为甲基铝氧烷)(Ⅰ)和Cp*T i(OC6H4F)3/MAO(Ⅱ)催化单一乙烯单体聚合制备长支链聚乙烯。13C核磁共振谱分析结果表明,催化剂体系Ⅰ制备的聚乙烯产物的支链全部为长支链(支链碳原子数大于等于6),而催化剂体系Ⅱ制备的聚乙烯则含有长支链和侧甲基;升高聚合温度和增加铝钛比都使产物的支化度增加;对于催化剂体系Ⅱ,升高聚合温度有利于α-烯烃大分子单体进行2,1-插入反应,使产物中侧甲基的含量明显增加;差示扫描量热分析结果表明,当相对分子质量相差不大时,支化度较高的聚乙烯具有较低的熔点。
Long- chain branch polyethylene was prepared by homopolymerization of ethylene over two novel mono - titanocene catalyst systems, namely [ Cp·Ti （ OC6H4Cl） 3 ]/MAO （ Cat Ⅰ ）, where Cp·was η^5- pentamethylcyclopentadienyl and MAO was methylaluminoxane, and [Cp·Ti （OC6H4F） 3 ]/MAO （ Cat Ⅱ ）. 13^C NMR indicated that branched chain polyethylene with long chain branches （ carbon number more than 6 ） was only synthesized on Cat Ⅰ , while polyethylene with methyl pendants and long chain branch was prepared over Cat Ⅱ. Raising polymerization temperature and n （Al） ： n （Ti）resulted in high branching degree of polymer. For Cat Ⅱ, 2,1 -insertions increased with increasing of polymerization temperature, and then polymer of high methyl pendant content were obtained. DSC analysis showed that polyethylene with higher branching degree had lower melting point when relative molecular masses of the polymers were approximate.
出处
《石油化工》
EI
CAS
CSCD
北大核心
2005年第9期875-879,共5页
Petrochemical Technology
基金
国家自然科学基金项目(20174050)
关键词
单茂钛催化剂
长支链
聚乙烯
大分子单体
均聚
mono - titanocene catalyst
long - chain branch
polyethylene
macromolecular monomer
homopolymerization
