Effects of ultraviolet aging on properties of wood flour-poly(lactic acid) 3D printing filaments

Abstract

An ultraviolet (UV) aging test chamber was used to analyze the aging behaviors of wood flour-poly (lactic acid) (PLA) 3D printing filaments under different temperatures. The materials were granulated using a twin-screw extruder, and the filaments were prepared using a single-screw extruder. The aging resistance was determined by comparing the color, tensile strength, scanning electron micrographs, and water absorption rate of the filaments before and after being processed. The aging behaviors tended to be stable when tested at 40 °C for 80 h, or 50 °C for 60 h, or 60 °C for 40 h. At this status, the tensile strength of the filaments was reduced by 44% compared to the originals; the internal structure of the filaments was severely damaged from the SEM images, and obvious porosities can be identified. The water absorption rate was greatly improved. The chromatic degradation (ΔE*) increased to 10.8 when tested at 40 °C, while this value increased to 10.9 at 50 °C and 10.8 at 60 °C. Therefore, the increase of aging temperature accelerated the UV aging process. It is recommended to add some ultraviolet absorbent into the filaments in order to improve the UV resistance of the materials.