THE INFLUENCE OF EXTRUSION PARAMETERS ON THE MECHANICAL-PROPERTIES OFPOLYPROPYLENE SHEET

Extruded thermoplastic sheet is widely used in the production of thin- gauge tubs and containers for the food and beverage industry using the thermoforming process. The production of high quality thermoformed pa rts is critically dependent on the standard of extruded sheet feedstoc k used. The extrusion process itself imparts a thermal history to the sheet, and this in turn partly dictates its subsequent thermoformabili ty. This paper assesses the influence of various extrusion parameters on the mechanical and morphological properties of polypropylene sheet, with a view to defining the optimum extrusion conditions for polyprop ylene. The extrusion parameters under consideration are chill-roll tem perature, line speed, sheet thickness and melt temperature.