This invention relates to a low heat release, low density, fiber-reinforced composite comprising a matrix comprising a thermoplastic polymer selected from the group consisting of polyarylsulfone, polyethersulfone, polyetheretherketone, polyetherketoneketone, a copolycarbonate of 4,4'-thiodiphenol and at least one member of the group consisting of bisphenol A, 9,9-bis(4-hydroxyphenyl)fluorene, and 1,1-bis(4-hydroxyphenyl)-1-phenyl ethane, a copolycarbonate of bisphenol A and 9,9-bis(4-hydroxyphenyl)fluorene, 1,1-bis(4-hydroxyphenyl)-1-phenyl ethane polycarbonate, bisphenol A polycarbonate, and polyetherimide, and from about 10 to about 70 percent by weight of the composite of randomly oriented reinforcing fibers, less than 0.5 inch in length, distributed throughout the matrix. The matrix has a void volume of from about 20 to about 90 percent by volume. The composite has a thermoplastic skin layer on each of the major surfaces thereof. A process for making the composite is also disclosed.
Polymer molding processes, such as injection-molding processes, include use of a viscosity-reducing supercritical fluid additive resulting in less breakage of reinforcing fibers upon introduction into the mold.