This work presents results of nylon-based composites used in additive manufacturing (AM) subjected to 24, 48, 96, 168, 336, and 504 h of continuous exposure to UV and 50% humidity. Sample coupons were built on a Markforged Two^® printer. To mimic UV exposure, samples were exposed to 253 nm UV light (UV–C), whereas for humidity, samples were placed at 50% relative humidity and 22 °C in a bi-distilled water atmosphere. The effects of said exposure were measured in tensile, Charpy impact energy, mass absorption, and Shore hardness D tests. Nylon gained 5.6% ± 0.48 mass after 504 h. For Charpy, absorbed energy went down from 0.463 J/mm² to 0.28 J/mm² at 504 h of humidity exposure. For Shore D, the variation goes from 59.1 ± 0.82 for zero exposure to 66.8 ± 2.5 at 504 h of UV exposure. Conversely, UV exposure induced an increase in Young’s modulus and Shore hardness, while significantly reducing impact energy to 0.32 J/mm², indicating embrittlement confirmed by SEM analysis. FTIR analysis revealed hydrolytic degradation under humidity and photo-oxidative degradation under UV, affecting N–H and C=O bonds. These findings allow a designer to project the residual mechanical properties of a component up to its last day of service.

This work presents results of nylon-based composites used in additive manufacturing (AM) exposed during 24, 48, 96, 168, 336, and 504 hours of continuous exposure to UV and 50% humidity. Sample coupons were built on a Markforged Two® printer. To mimic UV exposure, samples were exposed to 253 nm UV light, whereas for humidity, samples were placed at 50% relative humidity and 22°C in a bi-distilled water atmosphere. The effects of said exposure were measured in tensile, Charpy impact energy, mass absorption, and Shore hardness D tests. nylon gained a 5.6% ±0.48 mass after 504 hrs. For Charpy, absorbed energy goes down from 0.463 J/mm^2 to 0.28 J/mm^2 at 504 h of humidity exposure. For Shore D, the variation goes from 59.1±0.82 for zero exposure to 66.8±2.5 at 504 h of UV exposure. Conversely, UV exposure induced an increase in Young’s modulus and Shore hardness, while significantly reducing impact energy to 0.32 J/mm², indicating embrittlement confirmed by SEM analysis. FTIR analysis revealed hydrolytic degradation under humidity and photo-oxidative degradation under UV, affecting N-H and C=O bonds. These findings allow a designer to project a component with mechanical properties according to the last day of service.