Spatially and temporally resolved crystallization and orientation of high performance polymers during additive manufacturing

Additive manufacturing of high-performance polymers enables light-weighting for aerospace applications and complexity enabled capabilities for military applications. While good progress has been made towards robust processing, the coupling of processing parameters to morphological evolution and resulting heterogeneities in material properties and their effects on mechanical performance still lacks detailed understanding. Extrusion-based 3D printing of polymers such as PEEK is challenged by fast crystallization kinetics far from equilibrium that lead to challenges in batch repeatability and inconsistencies in performance. Overall, degree of crystallinity and heterogeneities of crystallinity between roads and layers lead to weak mechanical performance. Real-time monitoring techniques, such as synchrotron X-ray scattering experiments, shed light on the evolution of crystallite size, alignment and crystallinity. Real-time wide-angle and small-angle scattering with a microbeam setup and an industrial printhead are used on a 7-axis table to capture temporally and spatially resolved crystallinity, crystallization kinetics and polymer alignment during the 3D printinging process. The result reveals 2D maps of crystallinity and crystallite orientation within roads and at road and layer interfaces. The real-time snapshot over several centimeters along the heated build platform and throughout the height of the printed roads offers never-before-seen details of heterogeneous crystallization kinetics and polymer morphology at interfaces during extrusion-based 3D printing of high-performance polymers and enables a facile way to optimize processing parameters for improved performance of additively manufactured parts.