Durability study of automotive additive manufactured specimens 2020-01-0957
The long term weathering behavior of three different 3D printable, non-stabilized UV cure resin formulations (A and B with thiol-ene, and C with acrylate chemistry) was studied using tensile testing, nano-indentation, and photoacoustic infrared (PAS-FTIR) spectroscopy. To this end, type IV tensile bars were printed from each resin system using a DLP 3D printer, and were post UV-cured under a broad spectrum source. Systems A and C showed a similar trend after weathering - they first experienced an increase in modulus and tensile strength, likely due to additional crosslinking of the residual unreacted species. This increase in mechanical properties was followed by a drop in modulus, tensile strength, and percent elongation due to the over-crosslinking and consequent embrittlement. Sample B, however, showed remarkable retention of the mechanical properties before/after weathering. Nano-indentation results were in good agreement with the tensile properties, showing a similar trend in hardness variations. Although systems A and C outperformed system B in photooxidation performance, all three systems demonstrated promising results considering no hindered amine light stabilizers (HALS) were used in the formulations. Both photooxidation and mechanical properties of the specimens are expected to improve after addition of HALS.
Forough Zareanshahraki, Amelia Davenport, Neil Cramer, Christopher Seubert, Ellen Lee, Matthew Cassoli
Eastern Michigan University, Colorado Photopolymer Solutions, Ford Motor Company