PP老化高分子材料毕业论文英文翻译.pdf

Available online at Polymer Degradation and Stability 93 (2008) 84e89 /locate/polydegstab Natural photo-aging degradation of polypropylene nanocomposites Jifang Li, Rui Yang*, Jian Yu, Ying Liu Institute of Polymer Science and Engineering, Department of Chemical Engineering, Chemistry Building, Tsinghua University, Beijing 100084, PR China Received 17 August 2007; received in revised form 19 October 2007; accepted 20 October 2007 Available online 1 November 2007 Abstract The natural photo-aging degradation of polypropylene (PP), PP/CaCO3 and PP/SiO2 nanocomposites were studied outdoor for up to 88 days. The chemical structure characterized by Fourier transform infrared spectroscopy (FTIR) and pyrolysis gas chromatographyemass spectroscopy (PGCeMS) showed that PP nanocomposites are much more susceptible to photo-degradation than unfilled PP. And the oxidation rate is faster with more filler amount. There are lots of chain scissions happened in PP nanocomposites, accompanied with the formation of ketone, alcohol, ester and unsaturated double bond. This severe chain scission led to great decrease of Mn and Mw, and the consequent small fragments would re- crystallize and increase the crystallinity of the nanocomposites. However, these effects do not relate to the ultraviolet character of the two nano fillers. 2007 Elsevier Ltd. All rights reserved. Keywords: Polypropylene; Nanocomposites; Photo-oxidation; Chain scission; Re-crystallization 1. Introduction improve PC’s light stability [4], while in polyethylene (PE