METHOD OF PRODUCING THERMOFORMED ARTICLES FROM GAS IMPREGNATED POLYMER

摘要

A solid state process utilizes gas impregnation to enhance thermoforming of thermoplastic material. If the gas is plasticizing, the article is thereby platicized for thermoforming. In some embodiments, the invention provides foaming the polymer prior to or during thermoforming by creating high levels of dissolved gas during gas exposure. Foaming may proceed spontaneously upon decompression from gas pressure, or foaming may be enhanced by heating the polymer sheet (112) near to or above the polymer~s glass transition temperature, thereby producing plasticized foamed polymer for thermoforming. When objects of unfoamed polymer are desired, foaming may be suppressed by thermoforming gas saturated articles under gas pressure. This process may be used to enhance the thermoforming performance of articles that have been previously foamed, including articles foamed by prior processes. In some embodiments, polymer is sufficiently platicized so that it may be foamed without heating. Platicization of the polymer is reversible.