Patent ID: 7910038

Claim:
A method of making a preform, comprising: creating a pressure differential between an inside and an outside of a perforated shape memory polymer mandrel in its temporary shape such that pressure outside the perforated shape memory polymer mandrel is greater than pressure inside the perforated shape memory polymer mandrel, the perforated shape memory polymer mandrel having i) a predetermined preform shape as the temporary shape and ii) a shrunken shape as its permanent shape, wherein the shrunken shape is configured such that it is removable from the predetermined preform shape, wherein the predetermined preform shape is a tube shape, wherein creating the pressure differential is accomplished by drawing a vacuum from inside of the perforated shape memory polymer mandrel or by flowing fluid from outside of the perforated shape memory polymer mandrel through to inside of the perforated shape memory polymer mandrel; wherein prior to creating the pressure differential, the method further comprises: inserting a flexible bladder into the perforated shape memory polymer mandrel in its permanent shape; inserting the mandrel having the flexible bladder therein into an external mold having the predetermined preform shape; heating the mandrel and flexible bladder to a temperature above a switching temperature of the mandrel; pressurizing the flexible bladder, thereby forcing the mandrel against the external mold; cooling the mandrel to a temperature below its switching temperature, thereby setting the temporary shape of the mandrel which corresponds to the external mold shape; removing the external mold, thereby releasing the perforated shape memory polymer mandrel in its temporary shape; and depressurizing the flexible bladder; depositing at least one material onto a surface of the perforated shape memory polymer mandrel as the pressure differential is maintained to ensure that the at least one material is held in place on the surface of the perforated shape memory polymer material by the applied pressure differential alone; setting the at least one material in the predetermined preform shape, thereby forming the preform; and maintaining the flexible bladder in the perforated shape memory polymer mandrel during creating, depositing and setting, and wherein creating the pressure differential further includes pulling an other vacuum on the flexible bladder such that pressure is the same both inside and outside of the bladder, and thus perforations of the perforated shape memory polymer mandrel are unobstructed by the flexible bladder.