Molten Pressure of Polyvinyl Chloride Under Processing Parameters in Counter-Rotating Twin-Screw Extrusion

TL;DR

This study uses simulations to optimize the extrusion of polyvinyl chloride by analyzing pressure, temperature, and screw speed.

Contribution

The study provides optimized extrusion conditions for molten PVC using ANSYS Polyflow simulations in counter-rotating twin-screw extrusion.

Findings

Optimal extrusion conditions for PVC were found at 439 kg/h outlet rate and 43 rpm screw speed.

Lower compression ratio screw designs enhance throughput and reduce melt temperature.

Barrier screw designs improve polymer melting efficiency.

Abstract

Thermal properties significantly affect extrusion energy efficiency and polymer processing. Relevant parameters include melt temperature, viscosity, and specific heat impact energy consumption, while thermal degradation limits processing temperatures within the screw and barrel. Traditional empirical methods used in polymer extrusion are often hindered by the complex relationship between screw speed and energy efficiency. Numerical simulations, particularly those using ANSYS Polyflow, offer a more precise approach for visualizing temperature, pressure, and shear rate distributions in the molten polymer, enabling better control of extrusion conditions. The screw’s geometric configuration, which includes sections for conveying, compressing, kneading, and mixing, plays a key role in determining flow behavior and performance. Studies on polymers using various screw configurations have revealed that screw designs with lower compression ratios enhance throughput and reduce melt temperature. Additionally, barrier screw designs improve the polymer melting efficiency. In this study, ANSYS Polyflow simulations were applied to analyze the flow behavior of molten PVC in a counter-rotating twin-screw extruder, focusing on the effects of screw speed and inlet flow rate on pressure, temperature, and velocity distributions. The results indicated optimal extrusion conditions for preventing degradation, with an ideal outlet rate of 439 kg/h at a screw rotational speed of 43 rpm. The pumping pressure of molten PVC by a twin-screw approach would be enough for entering the extrusion die.

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