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Measuring & Predicting Crystal Morphology in Fused Deposition Modeling

Published

Author(s)

Claire McIlroy, Jonathan Seppala, Anthony Kotula

Abstract

Semi-crystalline polymer melts are commonly used in fused deposition modeling. Although flows have a profound effect on polymer crystallization, the relationship between typical fused deposition modeling (FDM) deformation rates and printed-part crystal morphology is yet to be understood. Here FDM is used to print a wall of poly-lactic acid filaments. The linear rheology and quiescent crystallization kinetics are characterized, infra-red imaging is used to measure temperature variations during the FDM process, and optical microscopy is employed to determine the resulting crystal morphology. Our flow-enhanced crystallization model demonstrates that FDM-induced polymer stretch leads to higher nucleation density and greater space filling in the weld regions during printing. Consequently, after a post-printing thermal annealing process, the weld region of a deposited filament features smaller spherulites than the center, in agreement with optical microscopy data. Finally, flow-induced crystallization is proposed as a method to improve weld toughness.
Citation
Polymer-Based Additive Manufacturing
Publisher Info
ACS Books, Washington, DC

Keywords

polymers, additive manufacturing, crystallization

Citation

McIlroy, C. , Seppala, J. and Kotula, A. (2019), Measuring & Predicting Crystal Morphology in Fused Deposition Modeling, Polymer-Based Additive Manufacturing, ACS Books, Washington, DC, [online], https://doi.org/10.1021/bk-2019-1315.ch006, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=926986 (Accessed October 22, 2021)
Created June 18, 2019, Updated October 12, 2021