丙烯腈-苯乙烯共聚物对聚甲醛的热稳定化作用

Influence of Acrylonitrile-styrene Copolymer on the Thermal Stability of Polyoxymethylene Resin

研究了丙烯腈-苯乙烯(AS)共聚物对聚甲醛(POM)的热稳定化作用.结果表明,在动态混炼条件下,添加少量的AS共聚物可使POM的熔体稳定性和熔融滞留时间明显增大,AS最优添加质量分数为3%;在静态加热条件下,AS的加入可使POM在升温过程中的分解温度显著提高,在恒温过程中的失重率明显降低.在动态或静态条件下,AS共聚物对POM热稳定性的贡献效果一致,并且同时加入AS和三聚氰胺对POM的热稳定性改善更为显著.红外分析结果表明,AS对POM的热稳定化作用源于分子链上的氰基对甲醛的有效吸收.

The influence of acrylonitrile-styrene（ AS） copolymer on the thermal stability of polyoxymethylene（ POM） resin was studied. It was shown that,under dynamic melt blending conditions,the thermal stability of POM melt and the molten residence time could be significantly improved by adding just a small amount of AS,and the optimal mass fraction is 3%. Under static heating conditions,the addition of AS leads to a significant increase in decomposition temperature of POM system during the elevated temperature process,and an apparently decrease in the mass loss rate during the constant temperature process. In both dynamic and static conditions,the contribution of AS to the thermal stability of POM is similar,and the effect is even more significant by the combined use of AS and melamine. IR analysis revealed that the mechanism of the thermal stabilization of POM resin is the efficient absorption of formaldehyde by the —CN groups of AS copolymer.