Linear Low-Density Polyethylene Softening Point and Endothermic Curve Profile Correlation: DSC Technique

Abstract

Two different linear low-density polyethylenes (LLDPE) were investigated by successive self-nucleation and annealing (SSA) thermal fractionation via differential scanning calorimetry (DSC). Samples with the same density and melt flow rate, very close comonomer content, and different softening points were investigated according to the endothermic curve profile, heat of fusion, and lamellar thicknesses of the multiple peaks. Changes in these parameters due to the LLDPE molecular chain heterogeneity could be used to characterize and identify the differences between the polyethylenes. The sample with the lower softening point presented multiple peaks or crystalline fractions with lower lamellar thickness, lower content of polyethylene homopolymer with high lamellar thickness, and relatively wider peak area related to very small lamellar crystallites. Thus, in this study, using the SSA technique it was possible to identify the LLDPE with the most suitable thermal fingerprint profile for hot-melt film application.