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本工作用DSC方法对三种不同支化度的茂金属短链支化聚乙烯的等温、非等温结晶行为进行了研究 .样品为乙烯和己烯 1的共聚物 ,短支链主要为正丁基 ,分子量Mw =2 0 ,0 0 0 ,Mw/Mn<1 15 ,支化度 (每10 0 0C中CH3 数目 )分别为 1 6、10 4、40 .实验结果表明 ,茂金属短链支化聚乙烯结晶方式Ⅰ Ⅱ转变温度随支化度增加而降低 ,分别为 119 8℃、115 9℃、113 3℃ ;同时支链的存在降低了二次成核速率 ,增大了方式Ⅰ的结晶范围 ,总的结晶速度随支化度增大而减小
In this work, the isothermal and non-isothermal crystallization behaviors of three metallocene short-chain branched polyethylene with different branching degree were studied by DSC method.The samples were copolymers of ethylene and hexene 1, the main short chain branches were n-butyl , Molecular weight Mw = 20, 0 0 0, Mw / Mn <1 15, degree of branching (number of CHs per 100 C) were 1 6, 10 4 and 40 respectively. The experimental results show that metallocene short- The transition temperature of Ⅰ Ⅱ of polyethylene crystallizes decreases with the increase of degree of branching, which is 119 8 ℃, 115 9 ℃ and 113 3 ℃ respectively. The presence of branches reduces the rate of secondary nucleation and increases the crystallization rate of method Ⅰ The overall crystallization rate decreases with increasing degree of branching