In the rapidly evolving world of additive manufacturing, a groundbreaking study led by Sunil Bhandari from the University of Maine’s Advanced Structures and Composites Center is shedding light on the durability of large-format 3D-printed polymer composites when exposed to environmental moisture. This research, published in the open-access journal Composites Part C: Open Access (translated to English as “Composites Part C: Open Access”), holds significant implications for industries like energy, transportation, and infrastructure, where these materials are increasingly being deployed.
Bhandari and his team investigated the moisture absorption and mechanical degradation of three distinct material systems: carbon fiber reinforced acrylonitrile butadiene styrene (CF-ABS), glass fiber reinforced polyethylene terephthalate glycol (GF-PETG), and wood flour reinforced amorphous polylactic acid (WF-aPLA). These materials were subjected to accelerated water immersion tests at various temperatures, mimicking real-world environmental conditions.
The findings revealed that bio-based WF-aPLA absorbed significantly more moisture than its petroleum-based counterparts, CF-ABS and GF-PETG. “The bio-based material exhibited ongoing degradation that prevented saturation, which is a critical factor to consider for long-term applications,” Bhandari noted. This behavior highlights the importance of material selection in applications where moisture resistance is paramount.
The study also uncovered that the most severe mechanical losses occurred in the through-thickness direction, where more interbead interfaces and voids were present. “This anisotropy is a direct result of the additive manufacturing process and underscores the need for optimized build orientations to enhance durability,” Bhandari explained. Longitudinal specimens, on the other hand, showed better retention of strength and stiffness, indicating that the direction of printing can significantly influence the material’s performance.
The mechanical property degradation was found to progress in two stages: an initial rapid phase following an Arrhenius relationship with inverse temperature, and a slower secondary phase that deviated from this behavior. This nuanced understanding of degradation mechanisms can inform predictive modeling and material selection for reliable structures in outdoor environments.
For the energy sector, these insights are invaluable. As large-format additive manufacturing (LFAM) gains traction for producing large-scale components, understanding their long-term durability under environmental stress is crucial. “This research provides a roadmap for selecting the right materials and optimizing build orientations to ensure the longevity of LFAM structures in challenging environments,” Bhandari said.
The study’s findings not only support material selection and predictive modeling but also pave the way for future developments in the field. By addressing the challenges posed by moisture exposure and anisotropy, researchers and industry professionals can work towards creating more robust and reliable LFAM structures. As the energy sector continues to explore the potential of additive manufacturing, this research offers a critical foundation for advancing the technology and its applications.