Mapping Crystallization Kinetics during 3D Printing of Poly(ether ether ketone)

Additively manufactured, high-performance polymers are increasingly used to realize complex, three-dimensional (3D) products but remain challenging from the point of view of performance control. To correlate and ultimately predict relationships between process parameters and performance, it is essential to advance our understanding of the evolution of the morphology during printing. In this study, we demonstrate spatially resolved, real-time synchrotron wide-angle X-ray scattering analysis during 3D fused filament fabrication (FFF) of poly(ether ether ketone) (PEEK) to map crystallization kinetics during printing at an unprecedented level of detail. Specifically, our measurements provide the first complete 2D map of the crystallization of a deposited road during FFF. This map reveals a sloped crystallization front, with crystallization occurring sooner close to the print bed and increasing monotonically with height. Maps obtained at three different temperatures show an increase in onset time for crystallization with temperature, accompanied by an increase in the final degree of crystallization.