Abstract: A scrimless, pressure- and/or thermo-formable, porous or non-porous, rigid composite material is provided. The rigid composite material employs one or more unwoven (i.e., not woven nor a nonwoven) patterned supportive fiber layers on or within the rigid composite material. Where the rigid composite material does not require a supportive scrim, it avoids the disadvantages associated with these support structures such as additional weight and cost. The inventive rigid composite material also offers increased flexibility in forming and molding different part geometries, which is actively sought after by part designers and engineers.

Abstract: A fibrous substrate comprising a consolidated product of a fiber composition is provided comprising polyimide fibers; fibers selected from aromatic polyamide fibrids or polycarbonate fibers; aromatic polyamide fibers. A process of preparing a fibrous substrate is disclosed, comprising forming a layer from a slurry comprising a suspension solvent; and fiber composition comprising a combination of polyimide fibers; aromatic polyamide fibers; aromatic polyamide fibrids; each based on the total weight of the fibers in the fiber composition; dewatering the layer; and consolidating the layer to form the fibrous substrate; wherein a layer of polyimide fiber aromatic polyamide fibrid is applied to each surface of the fibrous substrate either before or after said consolidating step, and the substrate and polyimide layers are together subjected to a consolidating step. In another embodiment, articles comprising the above fibrous substrates are provided.