Mechanical property degradation of polylactic acid (PLA) 3D printed parts under ultraviolet radiation

Abstract

This study investigates the effects of ultraviolet radiation (UV) on mechanical properties of 3D printed parts made of polylactic acid (PLA). Groups of samples 3D printed from thermoplastic PLA by a material extrusion process (MEX) were subjected to artificial UV radiation of two different wavelengths, 310 nm UVB and 254 nm UVC in order to replicate the aging effect prolonged UV exposure has on such parts. After exposure the samples were tested for tensile or compressive strength and the results were compared to an unexposed control group. PLA parts exposed to radiation for 24 h exhibited reduced mechanical strength, with a reduction in tensile strength of 5% to 9% and a reduction in compressive strength of 6% to 13%. Radiation in the UVC spectrum had a stronger impact on mechanical properties. Scanning Electron Microscopy (SEM) was used to analyze the internal structure of exposed samples and revealed microstructural changes at the fracture interface of tensile loaded parts.