Processing-morphology relationships of compatibilized polyolefin/polyamide blends

The emulsifying effect of a polyethylene-based ionomer on the phase size/composition relationship was studied for polypropylene/polyamide and polyethylene/polyamide blends. The particle size measured for the uncompatibilized blends increased with minor phase concentration, particularly as the region of dual phase continuity was approached. This relationship was less pronounced when ionomer was added, and the dimensions of the dispersed phase were significantly reduced. A narrowing of the region of dual phase continuity was observed due to the addition of ionomer. An increase in the torque measured during melt blending in a Brabender mixing chamber resulted when ionomer was added, due to the increase in the interactions at the interface. The particle size determined for the uncompatibilized blends increased with viscosity ratio. The effect was also less pronounced for the compatibilized blends. From these observations, it was possible to conclude that the effect of interfacial modification on morphology predominates over that of composition and viscosity ratio. The effects were interpreted in terms of the reduction of interfacial mobility due to the compatibilization.