Extrude structural composite profiles.

Until now, extrusion of long-fiber reinforced thermoplastics was thought to be impossible because there was no way to consolidate the composite well enough to hold its shape. However, Intek Plastics Inc. in Hastings, Minn., says it has developed a process that for the first time allows extrusion with glass fibers up to 1 in. long. Intek's new Very High Modulus Extrusion (VHME) process reportedly presents an alternative to pultrusion, wood, aluminum, or steel, and has dozens of potential uses in structural parts such as windows, doors, wastewater and sewage treatment, corrosive environments, commercial refrigeration and transportation, appliances, office furniture, and sporting goods. One current application is a replacement for wood in the sub-floors of refrigerated semi-trailers, where plastic provides better insulating properties and 65% lighter weight.

SUPER-STIFF COEXTRUSlONS

Intek's patent-pending process involves two- or three-layer coextrusion of a core layer of glass-reinforced ABS or PP with an unreinforced skin of ABS, PP, or PVC. The company typically uses Celstran long-fiber compounds from Polymer Composites Inc. (PCI), Winona, Minn., a unit of Hoechst Technical Polymers. Typical starting glass length is 0.5 in. Technical director Michael May says a proprietary extruder and die design preserves glass length during extrusion. As a result, VHME profiles have tensile and flexural moduli in a range from 1.4 million to 1.5 million psi. The product also maintains its properties over a wide temperature range. Impact resistance of some compositions improves at -40F compared with room temperature.

Intek is also testing the process with nylon and TP urethane. The company has used fibers 1 in. long but has run into handling difficulties. The company may license its technology to other processors.