Surface modification through gradient morphology control of polymer blends

Ethylene-vinyl acetate(EVAc) copolymer was melt-grafted with hydroxy ethylmethacrylate(HEEA) and acrylamide (AAm), then blended with polypropylene(PP) in this study. It was found that both PP/EVAc-g-HEMA and PP/EVAc-g-AAm formed a gradient phase structure during annealing, as same as that of a PP/EVAc blend. The formation of the gradient phase structure resulted in accumulation of the dispersed phase on the sample surface. With the dispersed phase EVAc as a carrier, the grafted polar groups were transported onto the surface of the blend sample while forming an EVAc gradient dispersed phase. Due to the hydrogen bonding between the polyurethane (PU) paints and the polar groups grafted on to the EVAc, the coating adhesion was greatly improved and the peeling strength of the coating reached a high value of 800 g/cm without further treatment of the sample surface. Thus, the gradient phase structure control of blends is an effective way of material surface-modification of materials.