Isothermal and non-isothermal crystallization kinetics of polyamide 12 used in laser sintering

Laser sintering of polymers is a steadily improving additive manufacturing method. Mainly used materials are semicrystalline thermoplastics, and as part of those, polyamide 12 has established most. When semicrystalline polymers cool down from the melt, they exhibit volume shrinkage due to crystallization. This crystallization occurs non-uniformly within the produced parts and thus is responsible for part warpage. Aim of this study was to investigate the crystallization kinetics of an, in laser sintering widely used, polyamide 12-based polymer available by supplier EOS with appellation PA2200. For that purpose, several isothermal and non-isothermal DSC measurements were taken. The isothermal measurements were analyzed according to the theory of Avrami. Furthermore, the parameters of the crystallization model by Nakamura were calibrated, and both conditions were simulated. It was found that the isothermal data are very well describable by the theory of Avrami as well as the model by Nakamura can be used to model both conditions.