高聚物玻璃化转变温度和分子参数的关系 Ⅱ.分子量对玻璃化转变温度的影响

RELATIONSHIP BETWEEN GLASS TRANSITION TEMPARETURE (Tg) AND MOLECULAR PARAMETERS OF POLYMERS II. Effect of molecular weight on Tg

根据前文提出的理论模型,本文推导出下述表征高聚物数均分子量(M_n)与玻璃化转变温度T_8关系的理论公式: T_g=T_g~∞-K_g/M_n K_g=T_g~∞·σ~2(T_g)·M_u十几种高聚物的K_g理论计算位能较好地和实验值吻合。应用理论关系式具体计算了聚苯乙烯、聚氯乙烯、聚二甲基硅氧烷和聚α-甲基苯乙烯的T_g随分子量的变化,其结果是令人满意的。

The theoretical dependency of the glass transition temperature (Tg) on the degree of polymerization DP is deduced from the theory of the glass transition proposed in the previous paper:The theory agrees well with the experimental data taken from the literature for polystyrene, poly (vinyl chloride), poly (a-methyl styrene), poly (dimethyl siloxane) and poly (methyl methacrylate) with various tacticities. The theory leads directly to the relationship between the parameter Kg of the equation (Tg= Tg - Kg/Mn) and the molecular parameters. The agreement between the theoretical predictions and experimental measurments of Kg has been found to be satisfacory for a number of polymers.