a compatibilized polymer alloy has been developed which has excellent processability under thermaforming conditions and the molded articles produced from the alloy exhibit superior gloss , shrinkage , surface hardness , polarity , strength and high heat distortion . the alloy is , in general , comprised of a polyolefin composition , a polystyrene copolymer , or polymer blend , and a compatibilizing agent . this polymer composition or alloy is particularly useful in producing packaging materials and food containers .