INFLUENCE OF PRESSURE ON BULK-DENSITY OF POLYMER SOLID GRANULES AT DIFFERENT TEMPERATURES

Through the experimental investigation of solid granule compaction, it is demonstrated that the combined influence of pressure and temperatu re on the bulk density of solid polymer granules is very significant f or all materials, although the effect is different for different mater ials, especially amorphous polymer material, such as polystyrene. A di stinction is made between the effect of pressure and temperature on th e bulk density for various materials and this cannot be neglected in p olymer processing operations. The rheological property of solid polyme r particles must be considered in the design of the plasticating extru der screw, which forms the basis of many polymer processing methods. A lso, it is one of the probable reasons why extrusion using a grooved f eed section in the extruder barrel can enhance the throughput of mater ial compared with that of conventional extrusion. (C) 1998 John Wiley & Sons, Inc.