EFFECTS OF PROCESSING PARAMETERS ON THE IN-SITU COMPATIBILIZATION OF POLYPROPYLENE AND POLY(BUTYLENE TEREPHTHALATE) BLENDS BY ONE-STEP REACTIVE EXTRUSION

This paper concerns the effects of processing parameters on the in sit u compatibilization of polypropylene (PP) and poly(butylene terephthal ate) (PET) blends by one-step reactive extrusion in a corotating inter meshing twin screw extruder. This in situ compatibilization process wa s characterized by a sequential arrangement for the free radical graft ing of glycidyl methacrylate (GMA) onto PP and the interfacial compati bilization reaction between the GMA functionalized PP and the terminal carboxylic group of the PET. Among the processing parameters examined were feed rate (Q), screw speed (N), and specific throughput (Q/N). T heir effects were evaluated by the associated mechanical properties of final blends in terms of elongation at break and impact strength. Res ults showed that elongation at break and impact strength increased vir tually linearly with decreasing Q or N. Moreover, for a particular Q/N , they increased with decreasing Q with a concomitant decrease in N. F urther analysis of these results showed that it is through residence t ime that these parameters affect the performance of the above mentione d in situ compatibilization process. (C) 1996 John Wiley & Sons, Inc.