DSC melting behavior of irradiated low density polyethylenes containing antioxidants

The effect of antioxidants (0.5 wt% content) on the melting behaviour of low density polyethylenes, one branched and one linear, was examined with data obtained by DSC. The two polyethylenes exhibit noticeable differences in pure form: LLDPE has a higher melting point, lower heat of fusion and a more complex fusion endotherm than LDPE. The addition of antioxidants has a scarcely noticeable influence on the melting behaviour of LDPE whether irradiated or not, while in the case of LLDPE the effect is more visible. However, a careful analysis of the observed characteristics, peak temperatures and lamellae thickness distribution as well as heat of fusion, show that the observed effects are appearing as the consequence of chemical processes, scission and crosslinking, which occur in PE under either thermomechanical action (mixing in the course of the sample preparation), or radiation. (author)