远程“传染”对聚丙烯光氧老化的影响

Infectious Behavior of Polypropylene During Photo-oxidation

研究了聚丙烯(PP)在附近有其他聚合物存在下,其光氧老化受"传染"的现象.研究发现,PP的光氧化会受到邻近聚合物降解产物的影响而被加速,即发生光氧化降解的"传染".当"传染源"不同时,被"传染"的情况也有所不同.在PP、聚甲基丙烯酸甲酯(PMMA)、尼龙6(PA6)和苯乙烯-丙烯酸酯共聚物(PSB)中,PSB的降解产物影响最大,使得PP光氧化的降解速率成倍增长.老化后的PP或PMMA作为"传染源"时,对PP的光氧化降解速率有进一步的促进.这种"传染"行为与聚合物降解产物的种类和含量有很大的关系.

The infectious behavior of polypropylene （PP） by other polymers during photo-oxidation was investigated in a sealed silica chamber. It is the first time to demonstrate that the photo-oxidation of one polymer （ in this case PP, poly （ methyl methacrylate） （ PMMA）, polyamide 6 （PA6） and styrene-butyl acrylate copolymer （PSB）） could infect another polymer （in this case PP）. PP presented various sensitivities when it acted as the infected object. The carbonyl index of PP increased by 32. 3% , 8.7% , 1. 8% and 215.2% , respectively when PP was irradiated with PP,PMMA,PA6 and PSB as the neighbors compared to the isolated sample. The light stability of the neighbor polymers showed great effect on the acceleration. PSB,which is easy to be photo-oxidized and its volatile degradation products propagated easily in the chamber, showed the most significant acceleration effect on the photo-oxidation of PP. The concentration of the degradation products was also a key factor. When the aged PP and aged PMMA were used as the infective agents,the carbonyl index of PP increased more than that with the unaged PP as the infective agent. This interesting finding transferred a message that the photo-oxidation was propagated not only among adjacent polymer chains but also in relatively large space. It drove researchers to think more about the interaction of polymers at service conditions, especially when these polymers are in a closed atmosphere. In addition, the lifetime prediction should be more careful when there is such an interaction existed.