Polystyrene/polyethylene oxide copolymer cell size enlarger for foam

Polymeric foam and polymeric foam products that contain a foamable polymer material, at least one blowing agent, an infrared attenuating agent, and a polystyrene/polyethylene oxide copolymer are provided. In exemplary embodiments, the blowing agent contains an HFC. The maleic anhydride-styrene copolymer grafted with polyethylene oxide increases the cell size of the polymer foam and offsets or even negates the decreased cell size caused by an HFC blowing agent and/or infrared attenuating agents. In addition, the copolymer of maleic anhydride-styrene grafted with polyethylene oxide has a positive affect on the processability of the blowing agent(s) in the composition by both widening the process window and enhancing the solubility of the blowing agent in the polymer melt. Thus, the polystyrene/polyethylene oxide copolymer present in the inventive composition acts as a cell enlarger, a plasticizer, and a processing aid. A method of forming an extruded foam product is also provided.