Effects of Environmental Temperature and Humidity on the Geometry and Strength of Polycarbonate Specimens Prepared by Fused Filament Fabrication*

While it is known that the printing quality of fused filament fabrication is heavily affected by environmental temperature and humidity, there is little understanding of the relations between environmental conditions, geometry, and the mechanical properties of printed parts. We investigated those relations using polycarbonate. Infrared imaging analysis showed up to a 5.4 ^○C/mm thermal gradient when printing in an open-chamber with a heated build plate. Micro-CT scans showed an up to 11.7% porosity from polymer water content absorbed from environmental moisture. Meanwhile, tensile tests showed a mechanical performance loss associated with those defects, but, surprisingly, the transverse direction ductility increased at a higher porosity. Finally, the experimental results were combined with analytical and parametrical studies to elucidate quantitative relations between environmental conditions and printing quality. We envision that our studies can provide quantitative guidelines for the estimation of printing quality based on environmental conditions and help users to obtain desired printing results by considering environmental conditions.

Ref. Materials 2020, 13, 4414.