Crystallization—morphology—polymer processing correlations for IUPAC low density polyethylenes

Abstract

Abstract The crystallization behavior of three IUPAC low density polyethylene samples has been characterized by thermal analysis. Their rates of crystallization only are directly correlatable with their film forming ability in film blowing technology. The IUPAC samples possessed essentially indistinguishable physical properties, including differential scanning calorimetry (DSC) melting curves and rheological characteristics, but their propensity for crystallization was found readily to parallel their film forming ability and other characteristics associated with end‐use performance. The application of thermal analysis to assess crystallization is a unique diagnostic tool for measuring polymer film processability, which is well illustrated here using a few simple experiments made on the original polymer specimens and a polymer blend. Although all samples exhibit similar small‐angle X‐ray periodicities, the morphological differences assessed, particularly by microtomy‐optical microscopy, correlate with, and complement, the results of phase transformation kinetics responsible for film properties. Fractography‐scanning electron microscopy proves to be inferior to optical methods for revealing the morphology of these low density polyethylenes.