Abstract: Gelled premixes based on heat-resistant polymers whose Vicat softening point is higher than 100.degree. C., containing an impact strength improver and a lubricant for polyvinyl chloride and polyvinyl chloride-based compositions containing such gelled premixes. The incorporation of heat-resistant polymers in the form of gelled premixes results in perfectly homogeneous polyvinyl chloride-based compositions which are converted without any problems at the usual temperatures for processing polyvinyl chloride into shaped articles with improved heat resistance.

Abstract: The compositions contain di-trimethylolpropane as a viscosity reducer in a proportion of 6 to 9 parts by weight per 100 parts of polyvinyl chloride. They advantageously contain a lead compound as primary heat stabilizer and a neutral lead carboxylate derived from C.sub.8 -C.sub.30 fatty acids as lubricant. The compositions are particularly suitable for the manufacture of rigid articles such as housings for office processing equipment and for radio and television sets and gratings for cooling towers, by injection moulding.