Morphology‐processing relationships in polyethylene‐polyamide blends

Abstract

Abstract Blends of polyethylene (PE) and polyamide (PA) were prepared by a melt mixing process. The dependence of the number average size A n of the dispersed phase on hydrodynamic conditions not only of shear rate but also temperature, inter‐facial tension, viscosity of the blends (WU's treatment), and dispersed phase concentration were studied. The analysis of PE‐PA blend morphology shows A n to be the result of a balance between coalescence and disruption of the particles in the melt, and to display a strong increase in particle size when the minor component concentration is enhanced. These observations can be explained by a change in the rheology of the system. These assumptions are confirmed by the insertion in the blend of an ethylenemaleic anhydride (EMA) copolymer that yields EMA‐g‐PA graft copolymer during mechanical processing. Formation of this graft copolymer has been indicated by a strong particle size reduction and its concentration was measured by infrared experiments. The EMA‐g‐PA copolymer seems to decrease the blend interfacial tension and to deter the coalescence process.