The morphology of compatibilized polyolefin/polyamide blends was found to be significantly dependent on the concentration of a n ionomer compatibilizer (polyethylenemethacrylic acid-isobutyl acrylate terpolymer) in the blend. For a dispersed phase content of 10% by weight, a maximum reduction in phase size was observed when only 0.5% by weight of ionomer was added to the blend. A more significant reduction of the dispersed phase size was observed when the minor phase was nylon, due to interactions which exist between the ionomer and the polyamide. These interactions have been confirmed by Fourier transform infrared spectroscopy. At high concentrations of the ionomer, flocculation of the nylon dispersed phase was observed. In comparison to one-step mixing, blends prepared by two-step or batch mixing were characterized by a smaller dispersed phase when nylon was the matrix, and a larger particle size when nylon was the minor phase. The results observed are explained in terms of a speculative model of the interactions occurring across the nylonpolyolefin interface.

SynopsisThe influence of composition on phase size in immiscible polymer blends is examined both experimentally and theoretically. It was found for eight noncompatibilized blends, of widely varying particle size morphology, that a master curve of phase size versus log-relative composition could be obtained by shifting the data along the volume fraction axis. The magnitude of the shift factors (arn) correlates with the interfacial tension and viscosity ratio of the systems. The theoretical dependence of the master curve is proportional to q5 + @* dependence as in Tokita's theory, hut estimation of the coefficients to the @ and q5* terms indicates that the influence of power and shear stress on breakdown of the dispersed phase is significantly overestimated by the theory. A master curve is also generated for four compatibilized blends and the dispersed phase sizes are significantly less dependent on composition.

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The morphology and impact properties of polystyrene‐maleic anhydride/bromobutyl rubber blends have been studied as a function of interfacial modification and melt processing conditions. It is found that dimethylaminoethanol (DMAE) serves as a reactive compatibilizing agent for these blends and that the addition of DMAE results in a five‐fold reduction In the size of the dispersed phase. Evidence for covalent bond formation between the DMAE and the elastomer and reactive polystyrene phases is presented. The volume average diameter of the minor phase increases significantly as the screw rotation speed and the material throughput increase. In fact, control of various material and processing parameters can be used to effectively control the particle size distribution during compounding. Impact strength measurements are shown to be clearly dependent on the quantity of DMAE in the system as well as the concentration of elastomer. Saturation of the interface with DMAE is shown to be an important consideration.