The morphology of hyperbranched polymer compatibilized polypropylene/polyamide 6 blends

The influence of hyperbranched polymer grafted polypropylene (PP-HBP) on th e morphology of polypropylene (PP)/polyamide 6 (PA6) blends has been invest igated. The final morphology was strongly influenced by the PP-HBP compatib ilizer concentration. At low concentrations, PP-HBP acts as an emulsifying agent, reducing the size of the dispersed phase and preventing coalescence. This is due to the high reactivity and diffusitivity of PP-HBP rapidly for ming a high density of copolymers at the interface. Compared to the use of maleic anhydride grafted PP (PP-MAH) at identical concentrations, PP-HBP yi elded a smaller dispersed phase particle size. Therefore, PP-HBP allows the use of less compatibilizer to obtain identical morphologies. At higher com patibilizer concentrations, it has been shown that the PP-HBP efficiently s tabilizes the interface and inhibits both coalescence and breakup of the PA S droplets. The high concentration of reactive sites and the ability of PP- HBP to react with both chain-ends of PAS suggest that interfacial stabiliza tion occurs because of the formation of a partly crosslinked interface. The interfacial stabilization effects generated by PP-HBP should allow one to control the morphology of polymer blends in order to create specific functi onal morphologies.