AN INVESTIGATION ON RHEOLOGICAL AND IMPACT BEHAVIOR OF HIGH-DENSITY AND ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE MIXTURES

Blends of high density polyethylene (HDPE) and ultra high molecular we ight polyethylene (UHMWPE), with a content of UHMWPE up to 20% wt, wer e prepared using two different types of processing apparatus, a single screw extruder and an internal mixer, as a function of mixing time. A detailed morphological investigation revealed that UHMWPE is only par tially dissolved, even under the most intensive and extended mixing co nditions. Evaluation of melt viscosity of the blends showed a double e ffect of UHMWPE due to its slight dissolution and to its presence as a filler. A further analysis of the experimental data, confirmed that U HMWPE, with respect to its initial content, dissolved up to about 3% o nly. The dissolution effect is also validated by both impact strength behaviour, increasing with the amount of dissolved UHMWPE, and a cryst allization kinetics study by differential scanning calorimetry (DSC). Copyright (C) 1996 Elsevier Science Ltd