Abstract: A transparent and flexible composite membrane produced from two immiscible polymers. The first polymer is a polymeric fibrous network with interconnecting pores. The second polymer is an elastomer with a refractive index matching the first polymer. The resultant composite membrane is a transparent interpenetrated network of polymers with an altered molecular structure, and mechanical strength superior to the parent polymers. A method of producing the new composite membrane involves dissolving the elastomer in a suitable solvent to form a diluted elastomeric solution, impregnating the polymeric membrane with the elastomer by adding the diluted elastomeric solution to the membrane to form a wet composite membrane, and then drying the wet composite membrane to form an interpenetrated membrane.

Abstract: A fiber-reinforced composite material with graded stiffness, and method of making the same. The degree of stiffness variation may be controlled via modifications to the fabrication processes. Products with varying stiffness along their lengths are described. In one example, a dental post is fabricated from material according to the present invention which has one end with low stiffness adapted for insertion into the root of the tooth, and a high stiffness end suitable to support the restoration.