Composite product and a process for producing said product

A method of making a foamed cellulosic fiber-thermoplastic composite article comprising:

• A) providing a copolymer composition that includes:
• i) at least about 20 wt. % of a copolymer formed by polymerizing a mixture comprising:
• a) about 51% to about 99.9% by weight of one or more primary monomers, and
• b) about 0.1% to about 49% by weight of one or more anhydride containing monomers;
• B) combining about 30% to about 99.9% by weight of the copolymer composition with about 0.01% to about 70% by weight of one or more cellulosic fibers based on the weight of the combination;
• C) applying an amount of heat, mixing energy and pressure sufficient to:
• i) mix the copolymer composition and the cellulosic fibers;
• ii) react anhydride groups in the copolymer with hydroxyl groups in the cellulosic fibers;
• and
• iii) produce a blowing agent as a byproduct of the reaction in ii) and provide a foamable mixture of the copolymer composition and the cellulosic fibers;
• and
• D) forming the foamed article by placing the foamable mixture in a molding or extruding operation;
• wherein the foamed article has a structured foam central portion and micro foamed outer portion that surrounds the structured foam portion and has a higher density than the structured foam central portion;
• wherein the micro foamed outer portion comprises from about 5 to about 22 percent of an overall thickness of the foamed article;
• wherein at least 10% of the cellulosic fibers of B) were thermally modified to reduce an amount of available hydroxyl groups prior to being combined with the copolymer composition and wherein at least 5% of the cellulosic fibers of B) were not thermally modified, and,
• wherein the thermal modification of the cellulosic fibers is performed by heating at a temperature of from 160° C. to 250° C. at atmospheric pressure or at a temperature of from 120° C. to 230° C. at a pressure higher than atmospheric pressure.