Crystallization kinetics of polyetheretherketone during high temperature-selective laser sintering

P Chen, H Cai, Z Li, M Li, H Wu, J Su, S Wen… - Additive …, 2020 - Elsevier
P Chen, H Cai, Z Li, M Li, H Wu, J Su, S Wen, Y Zhou, J Liu, C Wang, C Yan, Y Shi
Additive Manufacturing, 2020Elsevier
Understanding the complicated crystallization process is important for controlling the
performance reproducibility and stability in high temperature-selective laser sintering (HT-
SLS). Therefore, in this paper, the performance of HT-SLS processed polyetheretherketone
(PEEK) is analyzed from the perspective of crystallization kinetics. It is found that each layer
of sintered powder undergoes the dynamic non-isothermal crystallization promoted by cold
powder coating (CPC) and the quasi-static isothermal crystallization during the part bed …
Understanding the complicated crystallization process is important for controlling the performance reproducibility and stability in high temperature-selective laser sintering (HT-SLS). Therefore, in this paper, the performance of HT-SLS processed polyetheretherketone (PEEK) is analyzed from the perspective of crystallization kinetics. It is found that each layer of sintered powder undergoes the dynamic non-isothermal crystallization promoted by cold powder coating (CPC) and the quasi-static isothermal crystallization during the part bed temperature (T b) maintenance of HT-SLS. The kinetic analysis shows 321° C is a theoretical T b for PEEK. However, due to the great sensitivity to the temperature drop of CPC, the practical T b is set around 332° C, at which the 1/t 1/2 approaches zero according to the extrapolated analysis of Hoffman-Lauritzen theory. The shrinkage is only caused by the dynamic non-isothermal crystallization of CPC, and the minimum powder feeding temperature is found to be 250° C by Nakamura analysis. In addition, the quasi-static maintaining of T b during HT-SLS can lead to extended planar subunit along c-axis, increased crystallite size perpendicular to (1 1 0) and (2 0 0), and higher mechanical strength.
Elsevier
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