低密度交联硬质聚氯乙烯泡沫塑料的研究

以酸酐和异氰酸酯为交联组分,糊用聚氯乙烯为基体树脂,制备了低密度交联硬质聚氯乙烯(Crosslinked-PVC)泡沫塑料。考察了甲基六氢苯酐、偏苯三酸酐和对苯二甲酸与甲苯二异氰酸酯及多亚甲基多苯基多异氰酸酯的不同官能度配比对模压块和泡沫塑料交联度的影响,酸酐/异氰酸酯配比对泡沫塑料的性能影响,不同[K]值PVC树脂对泡沫塑料的性能影响。研究表明,异氰酸酯和酸酐的官能度对模压块和泡沫塑料的交联度影响十分显著,模压块中过早产生交联对后续发泡过程不利。随着酸酐/异氰酸酯摩尔比的增加,泡沫密度减小,压缩强度降低,且泡沫密度达到最低密度的时间缩短。当糊用PVC树脂[K]值过小时,发泡体系容易发生并泡和中间鼓泡;当[K]值过大时,压缩性能反而下降。制备的Crosslinked-PVC泡沫塑料具有半互穿聚合物网络结构。

Study on crosslinked rigid polyvinyl chloride foam plastic with low density

Crosslinked rigid polyvinyl chloride foam plastic with low density was prepared using paste PVC resin as matrix resin,anhydride and isocyanate as crosslinked components.The effects of 4-methy-hexahydrophthalic anhydride(MHHPA),trimelitic anhydride(TMA),p-phthalic acid(PTA) and toluene diisocyanate(TDI),polymethylene polyphenyl isocyanate(PAPI) with different functionality ratio on crosslinking degree of the embryo and the foam plastic were investigated,and the effects of the molar ratio of anhydride to isocyanate and paste PVC resin with different K values on property of foam plastic were also studied.The results showed that the functionality of isocyanate and anhydride had an important effect on the crosslinking degree of the embryo and the foam plastic,and premature crosslinking had an adverse effect on the foaming process.With the molar ratio of anhydride to isocyanate increasing,the foam density,the compressive strength and the time of reaching the minimum foam density were all decreased.While the K value of the paste PVC resin was small,big bubble inside the foam plastic was observed,but if the K value was large,the compressive strength would decrease conversely.The structure of crosslinked-PVC foam plastic was semi-interpenetrating polymer network.