Removal of solvent from gels of high molecular weight crystalline polymers

Claim 1

A process of forming a shaped article comprising producing a free draining gel from a solution of a crystallisable, high molecular weight polymer under conditions which cause crystallisation of the polymer and after producing said gel, forming it into a shaped article by a process which includes the application of a non-random deformation process to the gel and which expresses solvent from the gel, the gel being formed by either (a) cooling a solution of the polymer to a temperature at which the solution is supersaturated with the polymer or (b) adding a miscible non-solvent to the polymer solution so that the solution is supersaturated, thereby obtaining a free draining gel which is sufficiently viscous that it is capable of supporting a stainless steel ball bearing 1.5 mm in diameter while the gel still contains solvent, the gel also being sufficiently coherent that it can be picked up with forceps without the gel disintegrating to any substantial extent, the solvent being only loosely associated with the polymer and readily drainable therefrom; and thereafter subjecting the gel to non-randon deformation by either pressing the gel between opposed surfaces or by stretching the gel to express the solvent and form the shaped article.