Characterization and Optimization of Polyethylene Blends

Abstract

Several series of polyethylene (PE) blends were prepared where one component is a conventional PE and the second is a conventional linear low-density polyethylene (LLDPE) or a metallocene-catalyzed LLDPE. A two-step isothermal annealing (TSIA) procedure is developed enabling the satisfactorily resolution of endothermic peaks of blends of low-density polyethylene with LLDPE using standard thermo-analytical techniques. The TSIA procedure enables the quantification of comp-onents in an unknown, previously calibrated blend. The quantitative analysis of PE blends by Fourier-transform infrared (FT-IR) spectroscopy is explored and achieved by the development of a linear relationship based on the ratio of two absorbances in an FT-IR spectrum. The method exhibits potential for routine analyses of PE blends that have been previously calibrated. Chemiluminescence (CL) monitoring is successfully applied to study the oxidative degradation of PE blends. The CL data are consistent with the thermal and physicomechanical properties of the blends with a decreased blend miscibility reflected in the CL data as a departure from the idealized behaviour observed for more miscible blends. The physicomechanical and optical properties of PE blends are investigated and the results used to optimize the composition of particular film blends and assess the effects of downgauging the film thickness.