Isothermal lamellar thickening in blends of linear and low-density polyethylene

Polyethylene blends were studied by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Binary blends of commercial li near polyethylene (LPE) with two low-density polyethylenes (LDPEs) of melt indexes, about 20 and about 0.27 g/10 minutes, were investigated. The blend s, with 10% and 50% LPE contents, and the pure LPE were isothermally crysta llized at 124 degrees C for up to 48 h under solid-liquid phase segregation conditions. Double melting endotherms were obtained for the blends. Result s show that, despite differences in crystallization kinetics between both t ypes of blends, the same depression in the LPE melting temperature and appr oximately the same LPE crystal thicknesses were found for the blend composi tions. In addition, the extent of occurrence of lamellar thickening in LPE during crystallization is a function of its content in the blend.