聚合温度对聚氯乙烯树脂结构和性能的影响

Influences of Polymerization Temperature on Some Structures and Properties of Poly(vinyl chloride) Resin

采用凝胶渗透色谱法、１３ＣＮＭＲ和ＤＳＣ法测定了悬浮聚合ＰＶＣ树脂的平均分子量、间规度、结晶度和玻璃化温度．结果表明：聚合温度下降，ＰＶＣ的平均分子量上升，分子量的对数值与聚合温度的倒数成正比；ＰＶＣ的间规度和结晶度均增大，在形成结晶的间规链段的最短长度（ξｍｉｎ）为６时，由间规度计算的结晶度理论值与测定值接近；分子量和结晶度增加的共同作用，使ＰＶＣ的玻璃化转变温度上升．

Poly(vinyl chloride)(PVC) resins were synthesized at different polymerization temperatures( T ) by suspension process. The average molecular weight ( M ), syndiotacticity, crystallinity and glass transition temperature ( T g) of PVC resin were characterized by GPC, 13 C NMR and DSC methods. The results showed that M decreased as T increased, the logarithmic values of M were proportional to the reciprocal of T , the syndiotacticity, crystallinity and T g increased with decreasing of T , the calculated crystallinity based on the syndiotacticity approached to the experimental value in the case of the value of the minimum sequence length for syndiotactic chain segment contributing to the crystallites was 6.