Energy grass/polylactic acid composites and pretreatments for additive manufacturing

The aim of this study was to find the effect of ball-milling pretreatment of silvergrass and comparing the effects of pretreatment on common lignocellulosic materials such as reed, switchgrass and pennisetum to evaluate the potential of raw materials for additive manufacturing. The size of ball-milled material was much smaller than the nozzle diameter of the 3D printer and the melting point of composite was lower than that of pure PLA according to differential scanning calorimetry. The structure of the surface became smoother distinctly and biomass dispersed better in PLA matrix after ball-milling based on scanning electron microscopy. X-ray diffraction results showed that the ball-milling treatment influenced the performance of the composite by destroying the crystalline region and increasing the amorphous region of raw materials. Besides, the PLA/silvergrass composites possessed better mechanical properties of tensile strength, Young's modulus and impact strength of 23.1 MPa, 652.9 MPa and 38.67 kJ/m(2), respectively. Compared to the composites that were prepared by alkali-H2O2 (AH) and by steam explosion (SE) treatment, the composite that was prepared by acid treatment (AT) exhibited higher tensile strength, Young's modulus and impact strength of 26.94 MPa, 720.36 MPa and 40 kJ/m(2) respectively. Silvergrass/PLA composite shows better thermal stability compared to pure PLA for additive manufacturing. Moreover, AT works as a promising pretreatment method in promoting the properties of wood-plastic composite compared to UT (untreated), AH and SE. The silvergrass/PLA composite could be used for additive manufacturing after ball-milling combined with AT. Graphic abstract