Comparison of carboxylated and maleated polypropylene as reactive compatibilizers in polypropylene/polyamide-6,6 blends

Using reactive extrusion, polypropylene is functionalized with maleic anhyd ride and compared on an equimolar basis to polypropylene that is functional ized with an asymmetric, carboxylic acid containing peroxide. The grafting efficiency for the asymmetric peroxide is double that obtained for the male ic anhydride system. Moreover, the asymmetric peroxide yields a functionali zed material with minimal molecular weight degradation and desirable mechan ical properties, relative to maleic anhydride-grafted polypropylene. In com patibilized blends of polypropylene and nylon 6,6, the polypropylene that w as functionalized with the asymmetric peroxide is found to be an improved c ompatibilizer compared to that of maleic anhydride-grafted polypropylene. T he differences in mechanical properties of the two different functionalized polypropylene materials and their respective blends are rationalized on th e basis of the grafting efficiency, molecular weight degradation during rea ctive extrusion, and effect of free functional species on the ability to fo rm graft copolymers in compatibilized blends. (C) 2001 John Wiley & Sons, I nc.