| 摘要 |
A foamed polymer article having low bulk density, high impermeability, good flexibility, and imperviousness to chemical attack, is made by blending a polymer having a high impermeability and a predetermined solubility parameter with elastomer particles having a solubility parameter close to that of said polymer; said blend characterized by having a Brabender viscosity change of 100-200 meter-grams per DEG F at a temperature corresponding to a Brabender viscosity in said blend, when melted, of 1500-2500 meter-grams; subjecting said blend to mechanical working to melt said blend under shear; injecting into said melted blend a foaming agent having a preselected gas-liquid phase change temperature, low toxicity, and being relatively non-flammable; allowing said melted blend to foam in response to gasification of said foaming agent at a temperature which provides effective closed-cell formation in a viscosity range of 1500-2500 meter-grams; and, extruding and cooling said foamed blend into a finished article. An apparatus for extending a foamed polymer/ elastomer blend is also disclosed. |
