Fabrication of flexible wood flour/thermoplastic polyurethane elastomer composites using fused deposition molding

Using three-dimensional (3D) printing technology, the wood flour (WF)/thermoplastic polyurethane (TPU) composites with different contents of WF and different modifiers were prepared by TPU/WF composite filaments. These filaments were fabricated through the melt-blending and melt-extrusion of TPU and WF. The mechanical properties, microtopography and chemical structures of the 3D printing products were examined by the mechanical testing machine, scanning electron microscopy (SEM), Fourier transformed infrared (FTIR), Xray photoelectron spectroscopy (XPS), and rheological property tester. The results showed that the tear elongation decreased gradually as the WF content increased, and the tensile strength firstly decreased and then increased. SEM and FTIR results revealed a good compatibility between TPU and WF after the modification with EPDM-g-MAH. The XPS results indicated that the diphenylmethyl propane diisocyanate (MDI) and EPDM-g-MAH modification positively affected the interfacial bonding property between WF and TPU. The examination of rheological properties of the TPU/WF composites indicated that the storage modulus, loss modulus and complex viscosity were significantly increased after the modification with EPDM-g-MAH. The tensile properties of the TPU/WF composites were also greatly increased after the modification with EPDM-g-MAH.