GPPS产品再加工颜色变黄的原因分析

Causes analysis of and production suggestions against yellowing of GPPS during re-processing

通过多次挤出透明聚苯乙烯(GPPS),模拟产品再加工,分析了多次挤出对GPPS黄色指数、熔体流动速率、相对分子质量、透光率、残留单体以及低聚物含量等的影响。GPPS残留单体含量,低聚物含量以及在后加工过程中受到高温、高剪切作用时的降解程度和被氧化程度是致使GPPS产品回收利用过程中颜色变黄的主要原因。建议在生产过程中加入少量酚类抗氧剂以改善GPPS产品再加工时颜色变黄的现象。

The effect of repeated extrusion on the yellow index, melt flow rate, relative molecular mass, transmittance, residual monomer and oligomer content of general purpose polystyrene （GPPS） was analyzed by imitating re-processing through repeated extrusion of GPPS. The main reasons why the GPPS products became yellow during recycling were residual monomer and oligomer content of GPPS, and degradation degree and oxidation degree of GPPS due to high temperature and high shear stress during post-processing. It was suggested that a small amount of phenolic antioxidants should be added in the production of GPPS in order to alleviate yellowing of the product during re-processing.