Flow instabilities are often encountered during extrusion of high molecular weight Polypropylene homopolymers. Traditional techniques of flow instability reduction such as addition of fluoropolymers or compatibilizers significantly increase the cost of the finished product. During this study it was found that blending small amounts of Poly (Ethyl Vinyl Acetate) EVA into the polypropylene PP matrix eliminates melt fracture formation within a reasonable operating window, maintaining acceptable mechanical properties. A wide range of EVA concentrations was tested using capillary rheometry, microscopy and mechanical analysis. The acceptable operating window without instabilities was determined by analyzing the extrudate surface under the microscope.
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