Intended to expand the property profile and application potential of polymeric wood substitutes, a new technology is available for license to make lightweight plastic lumber-type products that contain no wood fiber. Eovations, LLC in Bay City, Mich., a two-year-old affiliate of Universal Forest Products, is promoting a patented technology originally developed by Dow Chemical Co. to produce profiles from PE, PP, or other thermoplastics together with a mineral filler (various kinds can be used). The process involves two steps, which can be integrated or separate: extrusion of a billet of resin and filler, and die drawing to highly orient the polymer chains and create voids (“dynamic cavitation”) around the mineral particle. Voids are created when polymer is pulled away from the mineral during drawing. Those voids help reduce density of the finished profile to 0.5-1.0 g/cc without use of blowing agents. One of the unique effects of the die-drawing process is “fully fiberizing” the composite—producing a wood-like fibrous structure throughout the thickness of the profile (see photo).
Eovations is offering to license the technology, and it also can produce custom products itself from a production-scale line in Bay City and additional capacity coming on line this year in Selma, Ala. Though no licenses have been granted yet, Eovations is in discussions with a number of prospective licensees and several appear promising, according to a company spokesman. Eovations says profiles made with its technology surpass many types of wood as well as wood/plastic composites and foamed PVC in physical properties and outdoor durability. For example, the Eovations product withstands 580 in.-lb of dart impact at 20 C. It reportedly also shows less than 0.2% moisture absorption, improved resistance to warpage, low thermal expansion in the lineal direction, and resistance to mildew, mold, insects, and marine organisms. The product can have woodgrain or other surface texture and can be colored and painted. The wide range of potential applications ranges from typical plastic-lumber uses—decking, railing, and fencing—to door and window frames, roofing, siding, trim, concrete forms, pallets, truck beds, trailer components, stadium seating, signage, piers, marine pilings, seawalls, and temporary road beds.