In order to establish a degradation prediction method for plastics, Chemiluminescence, which can detect the initial oxidation of the samples with high sensitivity, was applied for estimating the degradation degree of plastic samples. In this study, polypropylene was used as a sample. The samples were degradated by oxidation in a Chemiluminescence measurement device and in a thermostatic oven. The accumulate rate of peroxides amount on these samples caused by degradation were estimated by Chemiluminescence measurements with Nitrogen atmosphere. The degradation prediction of samples on 60°C was calculated by these rates on 130-150°C. This prediction value by this method showed good agreement with the result from measurements, compared with the prediction method by oxidation induction time.

Polyethylene (PE)-based nanocomposites were developed using PE-grafted SiO₂ (PE-g-SiO₂) nanoparticles, which were prepared by grafting terminally hydroxylated PE having different molecular weights. The obtained PE/PE-g-SiO₂ nanocomposites were characterized in terms of the nanoparticle dispersion, the crystallization, and the tensile properties in a comparative way to pristine PE, PE/SiO₂ nanocomposites and previously reported polypropylene (PP)/PP-g-SiO₂ nanocomposites. Similarly to the PP grafting, the PE grafting markedly improved the dispersion of the nanoparticles in the corresponding matrix and accelerated the crystallization. The addition of 5.0wt% of PE-g-SiO₂ led to increments of the Young’s modulus and tensile strength over pristine PE by 23% and 11%, respectively, while the addition of unmodified SiO₂ hardly improved these properties. The reinforcing mechanism in the PE/PE-g-SiO₂ nanocomposites was also discussed.