Patent ID: 7371799

Claim:
Method of preparing a shape memory polymer material characterized by a T g exceeding room temperature whose rubber modulus and elasticity is derived substantially from physical crosslinking comprising melt blending a crystalline polymer selected from the group consisting of poly(vinylidene fluoride), polylactide, poly(hydroxybutyrate), poly(ethylene glycol), polyethylene, poly(ethylene-co-vinyl acetate), poly(vinyl chloride), poly(vinylidene chloride), and copolymers of vinylidene chloride and vinyl chloride with an amorphous polymer selected from the group consisting of poly(vinyl acetate), poly(methyl acrylate), poly(ethyl acrylate), and atactic poly(methyl methacrylate) at a temperature of 10˜20° C. above the melting temperature of the crystalline polymers, for a time sufficient to ensure good mixing, cooling the resultant blend to room temperature, introducing said blend into a press maintained at about 180° C., applying pressure to said blend, and then rapidly cooling the film thereby formed to an annealing temperature T g <T a <T m , where it is held until crystallization is complete and following which the film is cooled to room temperature.