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.