Foamed chlorinated polyvinyl chloride and compositions for making same

A foam product comprising expanded chlorinated polyvinyl chloride resin having a minimum chlorine content of at least 60% by weight composed of numerous cells throughout containing 5 to 50 parts by weight of a chlorofluoroalkane of 1 to 2 carbon atoms and retained nitrogen that is a decomposition product of 0.01 to 2 parts by weight of azodicarbonamide, all amounts are based on 100 parts by weight of the resin, the azodicarbonamide forms cell nuclei containing nitrogen as a decomposition product thereof which cell nuclei form expanded cells when the chlorofluoroalkane is introduced and expanded, the foam has a density of less than 20 lbs/ft.sup.3, at least 60% of the cells in the foam are closed cells, and the cells are smaller than 500 microns, said product being devoid of a substantial amount of an inorganic powdery substance and a substantial amount of a solvent for the resin.