Effect of functionalized EPDM and ROP compatibilizing agents in incompatible polyethylene / polyamide blends

Abstract

Graft copolymer and graft terpolymer were prepared by solution grafting of maleic anhydride(MAH) or acrylonitrile (AN) alone and a mixture of MAH and AN onto ethylene-propylene-diene terpolymer (EPDM) using benzoyl peroxide(BPO) as an initiator. From this solution grafting method, three kinds of functionalized rubber[ EPDM-g-MAH, EPDM-g-AN, EPDM-g-(MAH-co-AN)] were obtained. The grafting reaction was confirmed with the aid of IR spectra and elemental analysis. All the grafted EPDM``s show a better thermal stability compared to virgin EPDM. The effects of the nature of the grafted species on the phase morphology, crystallization behavior and mechanical properties of the blends were characterized through scanning electron microscopy, optical microscopy and dynamic mechanical analyzer. Grafting reaction in extruder involves reaction of a molten polymer with a monomer or mixture of monomers capable of forming grafts to the polymer backbone. The functionalization of Reactive Polyolefin(RP or ROP) with MAH was carried out in Brabender twin-screw extruder. The MAH and initiator(DCP) concentrations were proportionally varied. From this melt grafting method, four kinds of functionalizde RP``s were obtained. Evaluation of the amount of grafted MAH onto the RP was performed by analysis of the IR and elemental analysis. The effects of the degree of grafting (DG) on the rheological properties, mechanical properties and morphology of HDPE/Nylon-6 blend containing these functionalized RP``s were investigated. For the Nylon-6/functionalized EPDM binary blends, when the functionalized EPDM rubber was added to Nylon-6, the mean size of the dispersed rubber phase is decreased by a factor of 5 to 8 to reach 1 $\mu$m or less compared to that of the plain Nylon-6/EPDM binary blend. It is to be noted that these domains have a rough surfaces with the evidence of strong adhesion with the matrix. Among the functionalized rubbers, it was shown that EPDM-g-(MAH-co-AN) has the strongest ef...