Importance

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Abstract

This invention provides a process for making microporous membranes from a polymer solution and the membranes therefrom. A thermal assist, such as heating of the polymer solution can be effected subsequent to shaping the solution, such as by forming a film, tube or hollow fiber of the solution under conditions that do not cause phase separation. In a preferred embodiment, the formed solution is briefly heated to generate a temperature gradient through the body of the formed solution. The polymer in solution then is precipitated to form a microporous structure. The formation of a wide variety of symmetric and asymmetric structures can be obtained using this process. Higher temperatures and/or longer heating times effected during the heating step result in larger pore sizes and different pore gradients in the final membrane product.

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First Claim