THERMOOXIDATIVE DEGRADATION OF LINEAR LOW-DENSITY POLYETHYLENE MELTS

Linear low density polyethylene (LLDPE) was thermally oxidized, in the presence of air, with cobalt (III) tris-(acetylacetonate) as a cataly st and dicumyl peroxide as an initiator. The solid residue was charact erized by elemental analysis (EA) and Fourier transform infrared spect roscopy (FTIR). Oxygen incorporation exhibited maxima when plotted aga inst temperature, time and additive concentration. The maximum incorpo ration, 11.5wt%, occurred after reaction at 150-degrees-C, for three h ours, with 4% catalyst and 0.4% initiator. Molecular weight was measur ed by gel permeation chromatography (GPC) and showed a minimum when pl otted against temperature. The number average molecular weight, M(n), dropped from 35 000 to 2500 after reaction at 150-degrees-C. Temperatu res up to 375-degrees-C led to approximately the same result, but high er temperatures yielded higher M(n). Weight loss was also measured, an d was found to increase with increasing temperature and reaction time.