CRYSTALLIZATION BEHAVIOR OF HIGH-DENSITY POLYETHYLENE LINEAR LOW-DENSITY POLYETHYLENE BLEND

Binary blend of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), prepared by melt mixing in an extruder, in the entire range of blending ratio, is studied for crystallization behavior by differential scanning calorimetry (DSC) and X-ray diffraction measurements. Cocrystallization was evident in the entire range of blend composition, from the single-peak character in both DSC crystallization exotherms and melting endotherms and the X-ray diffraction peaks. A detailed analysis of DSC crystallization exotherms revealed a systematic effect of the addition of LLDPE on nucleation rate and the subsequently developed crystalline morphology, which could be distinguished in the three regions of blending ratio, viz., the "HDPE-rich blend," "LLDPE-rich blend," and the "middle range from 30-70% LLDPE content." Variations in crystallinity, crystallite size, and d spacing are discussed in terms of differences in molecular structure of the components.