Tensile properties of 3D-printed wood-filled PLA materials using poplar trees

Fabrication of renewable materials through additive manufacturing using wood-filled polylactic acid (PLA) is an emerging field of study. The variability in the tensile properties of 3D-printed materials due to the variability in woody biomass properties has not been studied. Biomass size reduction, filament extrusion, and 3D-printing methods were investigated to determine the conditions that resulted in consistent printing. Using 20% ball-milled poplar reinforcement in PLA, 210 degrees C filament extrusion temperature and 230 degrees C printing temperature were found to be the best conditions. Subsequently, seventy poplar samples from a common garden were used to test the tensile properties of the printed materials. The median tensile strength at yield was 50 MPa, with 5-95 percentiles ranged in 37-54 MPa. Strain% at break had a median value of 2.1%, and 5-95 percentiles were 1.7-2.7%. The median Young's modulus was 3.65 GPa, and 5-95 percentiles ranged in 2.9-4.1 GPa. Biomass density was correlated to composite density. Median particle size of ball-milled poplar was negatively correlated with tensile strength. Composite density affected tensile strength of the composite. beta-glycosidic bond of polysaccharides in biomass affected Young's modulus of the composite. These data show that genotypic variation among Populus trichocarpa have substantial effect on tensile properties of 3D printed PLA-poplar materials. (C) 2020 Elsevier Ltd. All rights reserved.