Extrusion of thermoset wood-plastic composite (WPC) profi les with developmental melamine resins that have a thermoplastic processing window was presented at the WPC 2007 conference in Seattle last month by Agrolinz Melamine International GmbH and WoodKplus, a quasi-governmental research group, both in Linz, Austria.

Extrusion of thermoset wood-plastic composite (WPC) profi les with developmental melamine resins that have a thermoplastic processing window was presented at the WPC 2007 conference in Seattle last month by Agrolinz Melamine International GmbH and WoodKplus, a quasi-governmental research group, both in Linz, Austria. The material, called Hiperesin, is an etherifi ed melamine with increased molecular weight and controlled reactivity, giving it thermoplastic processing behavior. The special resin (WO 2006-136458) has shear-dependent viscosity and can be mixed with up to 70% wood fi bers and 5% other additives. The wood/melamine composite, called Hiperwood, is processed in a conventional conical twin-screw extruder at 266 F and extruded into a thermoset profi le, which is cured by passing through the heated die. The die-temperature profi le starts out cool at the entrance and rises to more than 338 F at the exit-the reverse of conventional thermoplastic extrusion, but similar to a pultrusion die. The benefi t of using melamine for WPC profi les is extra-high thermal/mechanical properties. Agrolinz: +43 (732) 6914-0 . www.agrolinz.com