Andrzej Nastaj

Multipurpose Computer Model for Screw Processing of Plastics

The state-of-the-art has been presented for computer modeling of screw processing of plastics. A new generalized approach for modeling of this class of plastics processing techniques has been proposed. Single screw extrusion, twin screw extrusion, as well as injection molding are discussed. Various types of feeding machines, including flood feeding and starve feeding, are considered. An idea for a multipurpose computer system for comprehensive modeling of screw processing has been presented. A problem of optimization of screw processing has also been discussed.

Computer Modeling for Single-Screw Extrusion of Wood–Plastic Composites

Experimental and theoretical studies have been performed on the single-screw extrusion of wood–plastics composites. Experimental research has been carried out on the flow and melting of polypropylene (PP)-based composites with different wood flour (WF) content in the single-screw extruder. Based on these experimental observations, elementary models of the process phenomena have been proposed and a global model of the process has been developed. This global computer model includes the models of solid conveying, melting dependent on the wood flour content, melt flow in the screw, and melt flow in the die. 3-D non-Newtonian finite element method (FEM) screw pumping characteristics have been applied to model the melt flow in the metering section of the screw. The model predicts the extrusion output, pressure and temperature profiles, melting profile, and power consumption. The model has been validated experimentally. An effect of material slip on the extruder operation has been discussed including both slipping in the screw/barrel surfaces and in the extruding die.

Studies for Polyblend Behaviour in Screw Extrusion and Injection Molding Processes

Polyblend behaviour in the screw extrusion and injection molding processes was studied. Melting mechanisms for LDPE/PS polyblend were investigated, as well as a morphology development was observed. The break‐up mechanism and fibrillation, as well as coalescence were clearly visible. A computer model developed for screw extrusion was applied to study material behaviour. The model is based on the flow field description in the machine.