Study On Photo-degradation Character Of Polyethylene In Starch/pol Yethylene Plastics

In the field of degradable plastics, the exploitation andapplication of starch-base plastics are more and more abroad, andhave become one of the most effective solutions for plastic wasteproblem. In this thesis, the effect of starch on photo- degradationof polyethylene in the starch/polyethylene blend has been studiedwhen irradiated by UV. The results showed that photo-oxidativedegradation of polyethylene could take place obviously in thestarch/polyethylene blend although there were no ordinaryphotosensitizers. The analysis of their degradation productsindicated that two competitive reactions, which are cross-linkingand degradation, took place during the initial stage ofphoto-oxidation. In the stage, the molecule with lower molecularweight mainly occurred cross-linking, while the molecule withhigher molecular weight mainly occurred degradation. With thewhole reaction carried through, the degradation gradually becamepredominant. For the polyethylene with same starch content, theanalysis of their degradation products indicated that temperaturecould affect the photo-oxidation of polyethylene. When thetemperature of the irradiation rose, the photo-degradation degreeof polyethylene increased.