IN-SITU COMPATIBILIZATION OF POLYPROPYLENE-POLYETHYLENE BLENDS - A THERMOMECHANICAL AND SPECTROSCOPIC STUDY

Polypropylene (PP) and low density polyethylene (LDPE) were melt blend ed in proportions of 75/25, 50/50 and 25/75 w/w, respectively. Poly(pr opylene-g-maleic anhydride) (PP-g-MA) with 0.8 mol% maleic anhydride c ontent and poly(ethylene-co-vinyl alcohol) (EVAL) with 7.5 mol% vinyl alcohol content were added at a 50/50 w/w proportion as in situ reacti ve compatibilizers. Four series of compatibilized blends were produced containing 2.5, 5, 10 and 20 wt% compatibilizer in the final blend. T he compatibilization reaction was followed by a torque increase during mixing and by FTi.r. spectroscopy. A notable improvement in tensile s trength, elongation at break and impact strength was observed for all blends after compatibilization acid, in particular, for the blends con taining 10 wt% compatibilizer. Scanning electron microscopy (SEM), aid ed by micro-Raman spectroscopy, was used for investigating the morphol ogy of the blends. (C) 1998 Elsevier Science Ltd. All rights reserved.