a heat resistant polymer such as a styrene maleic anhydride copolymer which has been contaminated with a minor amount of a vinyl chloride polymer such as polyvinyl chloride may be stabilized sufficiently by incorporation of calcium carbonate to allow contaminated heat resistant polymer reclaimed in this manner to match the performance of non - contaminated heat resistant polymer . instrument panels comprising such heat resistant polymers and polyvinyl chloride polymers may thus be readily recycled and reused to form new molded articles exhibiting with little or no deterioration in properties .