Determination of Crystallization Kinetics of Polyetheretherketone in Material Extrusion Process using Numerical Simulation

Abstract

Despite considerable progress over the past three years, some issues remain in obtaining printed Polyetheretherketone (PEEK) parts printed by material extrusion process (MEX). The fast crystallization of PEEK during printing results in distortion, poor dimensional accuracy and low inter-filament adhesion. Optimizing the process requires a fine understanding of the material deposition and optimization of the features affecting the mechanical properties of the output. In this study, we modeled the polymer melt deposition on the substrate, heat transfer, and crystallization kinetics of PEEK. The isothermal and non-isothermal crystallization kinetics were determined for the processing range from the glass transition to the melting temperature. The non-isothermal crystallization of the polymer was applied to the process using the modified Nakamura non-isothermal crystallization equation. Moreover, the influence of the environmental temperature on the crystallization kinetics was determined for the deposition of the first layer on the substrate. This study determined the optimal process parameters to improve the mechanical properties of the manufactured parts, owing to a better interdiffusion of the polymer chains between the deposited layers and less porosity.