Abstract: An extruded structural article is disclosed. The article has a cap layer comprising a flame retardant thermoplastic urethane material. The flame retardant thermoplastic urethane material is a blend of a thermoplastic urethane and a flame retardant polymer, such as a halogenated polymer. The thermoplastic urethane material is cross-linked using cross-linking agents such as radical initiators to improve strength, weather resistance, and resistance to scratching, abrasion, or marring. The flame retardant thermoplastic urethane is typically blended in a first extrusion with minimal cross-linking, and then applied to a structural article during a second extrusion in which the cross-linking reaction is activated.

Abstract: An extruded structural article with reduced stress whitening is disclosed. The article has a styrenic alloy cap layer that is lightly plasticized to reduce the stress discoloration without degrading properties of the article. A plasticizer is blended with components of the cap layer, and the cap layer co-extruded with a structural core material to form the article.