A continuous die-drawing process is being used on a pilot scale to make large profiles of 30% to 35% wood flour in PP.

A continuous die-drawing process is being used on a pilot scale to make large profiles of 30% to 35% wood flour in PP. PSA Composites LLC in Kent, Wash., owns the process, which was previously licensed to Green Forest Engineered Products in Nevada, Mo., for making smaller profiles. PSA's process reportedly makes composite profiles that are stronger and lighter by being stretched as they pass through the die, leaving air-filled microvoids behind each wood fiber. PSA's profiles have densities of 0.5 to 0.65 g/cc, comparable to soft pine, and withstand loads of 200 lb/in.2 while spanning 18 in. between joists. Competing wood-plastic boards are typically designed to span 16 in. or less between joists. Water absorption is low-1.39% thickness swell (ANSI 135.6) vs. 2.13% for other wood composites that typically have higher wood content of 50% or more. Lateral nail resistance is an impressive 820 lb/in. vs. 280 lb/in. for most boards. Modulus of rupture in bending is 6460 psi vs. 2500 for the competition. Die drawing of wood-plastic composites was developed by Frank Maine in Guelph, Ont. PSA: (253) 872-7600 . www.psacomposites.com