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<p>The surface quality of 3D-printed polymer parts is inherently limited by the characteristics of the additive manufacturing process. To mitigate these limitations, chemical post-processing is commonly employed to improve surface smoothness. However, this is often done without considering the potential adverse effects on the material’s mechanical performance. This study examines the influence of chemical post-processing on the mechanical behavior of 3D-printed polylactic acid (PLA) parts. Test specimens were fabricated using an Ultimaker 2 + 3D printer in accordance with ASTM D638 standards, with fibers oriented at ± 45° and 100% infill density. The samples were exposed to chloroform and dichloromethane vapors at room temperature (20&#xa0;°C) for durations ranging from 5 to 120&#xa0;min. Surface roughness was measured to quantify the smoothing effects of solvent exposure over time. Raman spectroscopy was subsequently used to assess potential chemical changes in the polymer structure. Mechanical characterization included tensile testing to determine tensile strength, strain, and elastic modulus, as well as stress relaxation and creep tests to evaluate time-dependent mechanical behavior. The results indicated a reduction in surface roughness of up to 79% with chloroform after 30&#xa0;min and up to 57% with dichloromethane after 10&#xa0;min. However, significant reductions in mechanical properties were observed post-treatment. After 15&#xa0;min of exposure, the elastic modulus and tensile strength decreased by approximately 80% and 70%, respectively, for dichloromethane, and by 88% and 77% for chloroform, relative to untreated samples. Additionally, treated samples exhibited increased ductility. Stress relaxation tests revealed a potential for premature failure under constant strain, attributed to reduced tensile strength, thereby compromising the material’s service life. Creep tests confirmed that solvent treatment induced plastic deformation, with treated specimens showing faster deformation rates. This resulted in a diminished capacity to dissipate mechanical energy, accelerating crack propagation and failure mechanisms.</p>

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Impact of CH2Cl2 and CHCl3 on the mechanical behavior and surface smoothing of FDM 3D-printed structures

  • 期刊论文

  • 发表日期：

    2025年7月22日

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  • Francisca Alarcon,
  • Angelo Oñate,
  • Cristián Vicuña,
  • Manuel Melendrez,
  • Carlos Medina

摘要

The surface quality of 3D-printed polymer parts is inherently limited by the characteristics of the additive manufacturing process. To mitigate these limitations, chemical post-processing is commonly employed to improve surface smoothness. However, this is often done without considering the potential adverse effects on the material’s mechanical performance. This study examines the influence of chemical post-processing on the mechanical behavior of 3D-printed polylactic acid (PLA) parts. Test specimens were fabricated using an Ultimaker 2 + 3D printer in accordance with ASTM D638 standards, with fibers oriented at ± 45° and 100% infill density. The samples were exposed to chloroform and dichloromethane vapors at room temperature (20 °C) for durations ranging from 5 to 120 min. Surface roughness was measured to quantify the smoothing effects of solvent exposure over time. Raman spectroscopy was subsequently used to assess potential chemical changes in the polymer structure. Mechanical characterization included tensile testing to determine tensile strength, strain, and elastic modulus, as well as stress relaxation and creep tests to evaluate time-dependent mechanical behavior. The results indicated a reduction in surface roughness of up to 79% with chloroform after 30 min and up to 57% with dichloromethane after 10 min. However, significant reductions in mechanical properties were observed post-treatment. After 15 min of exposure, the elastic modulus and tensile strength decreased by approximately 80% and 70%, respectively, for dichloromethane, and by 88% and 77% for chloroform, relative to untreated samples. Additionally, treated samples exhibited increased ductility. Stress relaxation tests revealed a potential for premature failure under constant strain, attributed to reduced tensile strength, thereby compromising the material’s service life. Creep tests confirmed that solvent treatment induced plastic deformation, with treated specimens showing faster deformation rates. This resulted in a diminished capacity to dissipate mechanical energy, accelerating crack propagation and failure mechanisms.