Browsing by Author "Waennil P."

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    Morphological evolution of polymorphic crystalline structures during 3D-printing of polypropylene
    (2026-07-01) Waennil P.; Ree B.J.; Falcone S.; Long M.; Singkammo S.; Kim J.H.; Jin K.S.; Rugmai S.; Punwong P.; Waennil P.; Mahidol University
    This study establishes a quantitative framework for morphological evolution during three-dimensional (3D) printing of polypropylene, a commodity thermoplastic, using spatially resolved, in-situ synchrotron micro-focused wide-angle X-ray scattering (WAXS). Measurements at varying bed temperatures and local heights within the printed road enabled direct quantification of polymorph selection, crystallinity, lattice parameters, orientation, and crystallization kinetics. WAXS patterns remained isotropic under all conditions, indicating the absence of preferred crystalline orientation induced by printing. Crystallization proceeded from the amorphous melt through abrupt formation of α and γ phases, followed by lattice densification and progressive crystallinity growth. Morphological parameters depended systematically on bed temperature and spatial height. Height-dependent crystallinity confirms a thermal gradient across the printed road, arising from low polymer thermal conductivity and asymmetric boundary conditions imposed by the heated bed and ambient air. A proposed kinetic model captures the full crystallization pathway. Primary crystallization dominates and precedes secondary crystallization (regime-I and II), which remains minor. Both processes are strongly temperature dependent: increasing bed temperature suppresses crystallization rates due to reduced supercooling and enhanced diffusion-controlled chain mobility. Primary crystallization occurs via sporadic nucleation with mixed two- and three-dimensional growth and impingement, whereas secondary crystallization is governed by diffusion-limited chain rearrangement within interstitial regions of the primary crystalline framework. Despite significant spatial variation in absolute crystallinity, normalized crystallization kinetics show negligible height dependence, indicating that the thermal gradient does not alter the underlying nucleation and growth mechanisms. Overall, these results demonstrate that in-situ synchrotron WAXS provides a rigorous quantitative platform for correlating thermal history, spatial position, and crystallization kinetics in polymer additive manufacturing, thereby offering fundamental guidance for morphological control in additively manufactured PP components.
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    Recent insights into morphology evolutions during 3D printing processes of advanced materials
    (2026-01-01) Ree B.J.; Sinta J.; Pyo R.; Waennil P.; Singkammo S.; Rugmai S.; Ree B.J.; Mahidol University
    Three-dimensional (3D) printing technologies have attracted significant interest from both academia and industry because of their extraordinary power and merits in manufacturing products over traditional manufacturing techniques. They are particularly well suited for the fabrication of complex 3D structures. Over the past two decades, substantial research and development efforts have led to remarkable advances in these technologies. Nevertheless, significant challenges remain, particularly in establishing comprehensive and reliable databases that capture the evolution of morphological structures during the printing process. Such structures include hierarchical features across multiple length scales and orientations, dimensional accuracy, and surface quality. These data are essential for optimizing processing conditions, understanding structure–property relationships, improving property performances, and expanding the global additive manufacturing market. Real-time approaches for monitoring morphological evolution during 3D printing have been demonstrated; however, their implementation remains at an early and relatively limited stage. In-situ scattering techniques enable probing of hierarchical structures from atomic to micrometer length scales, while real-time microscopy methods provide complementary information on porosity, geometry, and material dynamics during fabrication. To date, however, these studies have focused on a narrow range of materials and have largely relied on basic or qualitative analyses. This highlights the need for broader adoption of such techniques and for more rigorous, quantitative data analysis to establish robust correlations among processing parameters, structural evolution, and resulting material properties. This article reviews real-time morphology analysis techniques that have been implemented or are under development for 3D printing technologies, along with the analytical outputs they generate. It also discusses perspectives on future advances in in-situ monitoring of morphological evolution across all areas of additive manufacturing.