Abstract: The present invention provides thermoplastic roofing membranes comprising particles of crosslinked rubber and an aqueous (co)polymer dispersion. The thermoplastic roofing membranes are formed by combining particles of crosslinked rubber and a suspension polymer dispersion, or a coagulated aqueous latex (co)polymer dispersion, to form a mixture in aqueous dispersion, which aqueous dispersion mixture is subjected to solid state shear pulverization to form materials that can be processed as thermoplastics at crosslinked rubber concentrations of from 10 wt.% to as high as 95 wt.%, based on the total solids of the material. The method may further comprise kneading the pulverized product, followed by extrusion to form roofing membranes.