EXPERIMENTAL AND THEORETICAL-ANALYSIS OF THE RIGHT-ANGLE EXTRUSION OF POLYETHYLENE AT ROOM-TEMPERATURE

In order to obtain high-performance polymer end products, processing of crystalline polymers below their softening temperature has been employed and studied in recent years. It has gathered attention, for example, in the area of producing high-strength polymer rods and filaments of higher cross-sectional area for special applications. Die drawing and extrusion techniques dominate the processes used to achieve these products. Extrusion is primarily achieved by forcing the polymer through converging dies of circular and other cross-sections. The methods of solid-state extrusion processing practiced are primarily ram extrusion and hydrostatic extrusion. In this study, we investigate the process of producing cylindrical rods by ram extrusion of plastics at room temperature. Instead of using a converging die, right angle dies of varying extrusion ratios are employed to extrude three commercial grades of polyethylene. A theoretical analysis is also performed to predict the forces required during extrusion. The theoretical analysis closely follows the methodology presented by Coates et al. for the circular extrusion of polymers below their softening temperatures. (C) 1995 John Wiley & Sons, Inc.