聚丙烯分子结构与聚合工艺对挥发性有机物的影响

Effects of polypropylene molecular structure and polymerization process on volatile organic compounds

对不同工艺生产的聚丙烯(PP)进行了挥发性有机物(VOC)的精准测定,研究了聚合物分子结构、聚合物分子量、聚合后处理工艺、分子量调节方法等对PP中VOC的种类和含量的影响。实验结果表明,VOC主要在PP均聚阶段形成,共聚阶段对VOC的形成影响不大。随着PP熔体流动速率的提高,PP中的总VOC(TVOC)含量均不同程度地增加。聚合后期的汽蒸干燥工艺可有效降低共聚PP中的TVOC含量,而脱气工艺对降低TVOC含量的作用较弱。氢调法共聚PP中TVOC含量比降解法PP的TVOC含量低。

The volatile organic compound(VOC)in polypropylene(PP)produced by different processes were accurately determined.Then the effects of molecular structure,molecular weight,post-polymerization treatment process and molecular weight adjustment method on compositions and contents of VOC in PP were studied.It is found that VOC are mainly formed in the homopolymerization stage instead of the copolymerization stage of PP resin.With the increase of melt flow rate of PP,the total VOC(TVOC)content of PP resin increases in varying degrees.The TVOC content of PP resin is decreased effectively by steam drying process in the later stage of polymerization,while the effect of degassing process is not obviously.Moreover,the TVOC content from copolymerized PP by hydrogen regulation method is lower than that by degradation method.