CHARACTERIZATION OF LINEAR LOW-DENSITY POLYETHYLENE BY TEMPERATURE RISING ELUTION FRACTIONATION AND BY DIFFERENTIAL SCANNING CALORIMETRY

In this study, solution crystallized samples of LLDPE were characterized by differential scanning calorimetry (DSC) to ascertain the feasibility of utilizing the DSC technique as an alternative to analytical temperature rising elution fractionation (TREF). All steps, from dissolving the polymers to crystallizing by controlled cooling to analysis were performed in the DSC. The DSC results were compared with analytical TREF runs using two commercial LLDPEs (designated Resins A and B). Both techniques provided similar compositional distribution information with the calorimetric results being obtained in considerably less time. In particular, resins evaluated via both techniques showed distinct bimodal distributions, although the shapes of the curves were not identical. For example, as measured calorimetrically, Resins A and B contained approximately 69% and 59%, respectively, of the lower melting, more branched species. These results compared favorably with analytical TREF runs which indicated that Resins A and B contained about 68% and 58%; respectively, of the lower melting, more branched species.