微晶交联网络结构对增塑聚氯乙烯性能的影响

EFFECTS OF MICRO CRYSTALLITE CROSSLINKING NETWORKS ON THE PROPERTIES OF PLASTICIZED POLY(VINYL CHLORIDE)

研究了温度对ＰＶＣ断裂伸长率、拉伸强度及加热形变量（针入度）的影响，发现与未增塑ＰＶＣ相类似，增塑ＰＶＣ在９０℃左右出现断裂伸长率最大值；增塑ＰＶＣ的形变量随ＰＶＣ聚合度（结晶度）的增加而减小，软化温度则上升。对于退火处理的增塑ＰＶＣ，形变在退火温度所对应的重结晶熔融温度范围出现转折。认为以上实验结果与增塑ＰＶＣ中微晶交联网络结构的存在及其在升温条件下的破坏有关，提出了增塑ＰＶＣ的微晶交联结构物理模型。根据经典的橡胶弹性理论，计算了交联网络中交联点之间平均分子量（Ｍｃ），发现Ｍｃ随ＰＶＣ聚合度（结晶度）的增加而减小。

The effects of testing temperature on the elongation ratio at break, tensile strength and compression deformation(penetration) were investigated in this paper. It showed that plasticized PVC exhibited the maximum elongation ratio at 90 ℃, which was similar to the result of unplasticized PVC, the defromation value of plasticized PVC decreased with increase of polymerization degree(the degree of crystallinity) of PVC, but the soft temperature increased. The presented results also showed that the defromation varied rapidly in the melting temperature range of recrystallites corresponding to the annealing temperature for the annealed plasticized PVC samples. It suggested that the above results were related to the existence and destruction of micro crystallite crosslink networks in platicized PVC. The structural model of micro crystallite crosslinking network of plasticized PVC was proposed and the molecular weight between the crosslinks was calculated from modulus according to the classical rubber elasticity theory.