Annealing in low density polyethylene at several temperatures

Abstract

By using differential scanning calorimetry (DSC) techniques we show that three kinds of endotherms arise in low density polyethylene (LDPE) annealed between 45° C and 115° C. Of particular importance is the endotherm II, which reflects the melting of the crystallites generated at the annealing temperature by the partial melting/ recrystallization mechanism. For this case, the analysis of both the changes in the melting enthalpy and in the peak temperatures leads to the conclusion that the crystallization at the annealing temperature is not essentially different from that taken place isothermically and with an overall amorphous initial state. Finally, we also find the interesting result that the crystallinity degree associates only to the endotherm II pass through a maximum when we vary the annealing temperature.