A method of preparing a refrigeration insulation liner comprising forming a multilayer polymeric sheet comprising at least one foam layer and at least one solid layer disposed adjacent to the foam layer, shaping the multilayer polymeric sheet into the liner, wherein the liner is an insulator, wherein the layers of the sheet adhered to each other by melt extrusion, and wherein the liner resists degradation in the event of contact with a refrigerant. A method of preparing a refrigeration device liner comprising coextruding a foamed polystyrene layer between two solid layers of high impact polystyrene to form a sheet, thermoforming the sheet into the liner, and incorporating the liner into the refrigeration device. A method of forming a multilayer polymeric sheet comprising melting a first styrenic polymer composition, melting and foaming a second styrenic polymer composition, and coextruding the first and second styrenic polymer compositions to form a multilayer polymeric sheet.