Abstract: A new and improved structural material comprising an interpenetrating plastic and substrate network material composite including two phases, a first phase comprising a substrate of paper or paper-like material or other fibrous or absorbent material defining a fibrous network phase, and a second phase comprising a polymerized plastic material penetrating and intimately contacting the structure of the paper or other fibrous or absorbent material filling the voids and interstices between the fibers of the paper material and hardened to a desired condition of rigidity. The composite is formed by saturation and in situ polymerization from a solvolysis system. The composite material is further incorporated in a monolithic laminar structure by application of layers of the solvolysis adjusted for sufficient agglomerating and aggregative characteristics to form plastic weldments or fillets at intersections of the substrate portions.

Abstract: A new and improved structural system comprising an interpenetrating plastic and substrate network material composite including two phases, a first phase comprising a substrate of intersecting partitions of paper material or other fibrous or absorbent material defining a cellular lattice, and a second phase comprising a polymerized plastic material penetrating and intimately contacting the structure of the paper or other fibrous or absorbent material filling the voids and interstices between the fibers of the paper material and hardened to a desired condition of rigidity. The cellular lattice of composite material is coated with at least one coating of plastic material adherent to and chemically binding with the hardened composite surface and with sufficient agglomerating or aggregative characteristics to form plastic weldments or fillets at the intersections of the substrate partitions.