Bulk density of solid polymer resins as a function of temperature and pressure

✍ Scribed by Kun S. Hyun; Mark A. Spalding

• Publisher: Society for Plastic Engineers
• Year: 1990
• Tongue: English
• Weight: 537 KB
• Volume: 30
• Category: Article
• ISSN: 0032-3888
• DOI: 10.1002/pen.760301003

✦ Synopsis

Abstract

In a plasticating extruder, solid polymers are heated and are subjected to high pressures before they are melted and delivered to a die. In both the solids conveying and melting sections, these temperature and pressure increases will compact the unmelted polymer bed as it moves down the screw channel. Performance of the extruder depends in part on how well the screw design matches the compaction behavior of the resin for a given set of process conditions. The design of these screw sections, however, is often done based on past experience and with little knowledge of the resin compaction behavior. A much improved design would include screw performance prediction using variable bulk density and computer simulations. Computer simulations, however, are often performed using constant solid bulk density because of the lack of reliable density data as a function of both pressure and temperature. An instrument was developed for studying the compaction behavior of pellet and powder resins. Bulk densities and storage friction coefficients are reported for several important thermoplastic resins as a function of temperature and pressure. The bulk density data were fitted to a semi‐empirical model.