Reactive compatibilization of the PBT/EVA blend by maleic anhydride

This study concerns the reactive compatibilization of the blend of poly(but ylene terephthalate) (PBT) and ethylene/vinyl acetate copolymer (EVA) by ma leic anhydride (MAH). First, the graft copolymerization of EVA with MAH was investigated using dicumyl peroxide (DCP) as an initiator by melt free rad ical grafting in a plasticorder (Haake). The concentrations of MAH and DCP were varied from 0 to 3.0 phr and from 0 to 0.4 phr, respectively. EVA-g-MA H formed by the grafting reaction of EVA and MAH in the presence of DCP exh ibits a significantly lower torque value than EVA bearing no MAH. PET was b lended with thus-obtained EVA-g-MAH using the same plasticorder. For compar ison, PBT/EVA blend was also prepared. The FTIR spectroscopic studies showe d that PBT-g-EVA copolymer was formed by the in situ interfacial reaction o f MAH grafted onto EVA with the carboxylic and/or hydroxyl groups at the ch ain ends of PET in the blend systems. The impact strength of PBT/EVA-g-MAH (80/20) blend showed about three-fold increase in comparison with PBT/EVA ( 80/20) blend due to the enhanced interfacial adhesion by the formation of i n situ compatibilizer, i.e. PBT-g-EVA copolymer. Also, the morphology of th e blends was observed with scanning electron microscope (SEM). (C) 2001 Pub lished by Elsevier Science Ltd.