A new model for solids conveying in single-screw plasticating extruders

Solids conveying is the least understood operation for single-screw, plasticating extruders, yet it can be the source of many problems such as flow surging, low rates, high discharge temperatures, and material degradation. This lack of understanding has led to poor solids conveying models that do not describe conveying behavior. A new conveying model, however, has been developed that describes the pressure generation and thermal effects utilizing realistic physical property data. The model is compared to experimental solids conveying rate data for a low density polyethylene (LDPE) resin at several different process conditions and for two screws.