Effects of accelerated weathering on properties of 3D-printed PLA scaffolds

Abstract

This work aims to analyze the effects of accelerated weathering – under different environmental variables – on the properties of poly(lactic acid) (PLA) scaffolds fabricated by Fused Filament Fabrication (FFF). Two methodologies were followed: at 35 and 45 °C, under temperature control alone (ASTM F1980), and under controlled cycles of temperature, ultraviolet (UV) radiation, and humidity (ASTM G154). Weathered samples were characterized by color visual analysis, differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). For weathering tests at 35 °C, and simultaneous control of temperature, radiation, and humidity (T-R-H), the degradation seemed to predominantly affect amorphous parts of the PLA scaffolds. For weathering at 45 °C, the degradation was prevalent on amorphous parts for initial exposure and, subsequently, also affected crystalline parts of the polymer. The accelerated weathering tests produced changes in the FTIR spectra, indicating intensified chain scissions by photolysis and hydrolysis, with more pronounced effects for the T-R-H test, followed by the tests under 45 °C and 35 °C. Noticeable surface defects appeared only on PLA samples subjected to the T-R-H test (336 h exposure), as a result of the more severe degradation generated by the combined variables of this accelerated weathering. • Poly(lactic acid) (PLA) scaffolds manufactured by Fused Filament Fabrication (FFF) • Different accelerated weathering tests performed with the PLA scaffolds • Changes in properties, due to weathering, assessed and compared • Effects of weathering tests linked to PLA degradation mechanisms