In order to analyze the influence of molecular weight distribution(MWD) on photo-oxidation degradation properties of low density polyethylene(LDPE)

the materials parameters(chemical structure

thermal stability

average molecular weight

surface morphology and mechanical properties) of LDPE with different MWD index were studied by attenuated total reflection infrared spectroscopy(ATR-FTIR)

thermogravimetry analysis(TGA)

gel permeation chromatography(GPC)

scanning electron microscope(SEM) and mechanical experiments.The results show that the wide MWD of LDPE resulted in an obvious increasing in the degree of unsaturation and chain branching.For the narrow MWD of LDPE

the degree of carbonyl index increased significantly.The MWD had little effect on the behavior of chain breaking.For the high MWD index

the initial thermal decomposition temperature and 5% mass loss corresponding temperature of LDPE decreased faster

and thermal stability was apt to decline.The average molecular weight decreased much intensely and the aging phenomenon of surface microstructure was much severe.The bending strength and impact strength decreased faster

characterized by the loss of the impact strength of LDPE with 6.0 MWD index after 24 d of aging.Analytically

the large average molecular weight and narrow MWD indicated the long molecular chain and less short-molecular chain

and the probability of production of free radical by oxygen contact was also low.So the wider MWD of the PE

the easier of the material aging.