Cellulosic FDM 3D printing flexible material for apparel

Abstract

Cellulose powder and thermoplastic polyurethane (TPU) were the main materials of the composite fabricated in this research. The TPU matrix materials of the composite were analyzed with Fourier Transform Raman spectroscopy (FT-Raman) for discriminating chemical content. The hard and soft segment in all the TPU used in this research was identified. Meanwhile, the cellulose fillers for the composite were also ensured the purity by FT-Raman. On the other hand, the thermal properties of TPU and cellulose powders were assessed with Differential Scanning Calorimetry (DSC). The results insinuated the compatibility of the composite ingredients with no degradation when having melt processing. The morphology of the filler may affect the mechanical performance of the composite. Hence, the cellulose powder was observed with Scanning Electron Microscopy (SEM) and the particle size was determined at the same time. Those results were shown and discussed in Chapter 5. A twin-screw compounder was used to fabricate TPU / cellulose composite in this research. The formulation steps are described in Chapter 3 and separated into 3 stages. The procedure of the fabrication with a twin-screw compounder is described detailly in Chapter 4. The mechanical performance of the composites made in each formulation stage were evaluated with ISO 37 tensile test standard. The results are briefly concluded below, and the detailed discussion can be found in Chapter 5. In Stage 1, 6 kinds of cellulose powder and 6 different hardness of TPU were compounded with 1:9 volumetric ratio, creating 36 formulae. In which, 26 composites had been reinforced by increasing tensile strength. 1170 α-cell fine, 1170 L-cell fine, 45A α-cell fine were the 3 shortlisted formulae. In Stage 2, larger particle size of cellulose powder was blended into the TPU. Finally in Stage 3, the content of cellulose powder in the composite was increased until it was over-reinforced. The strongest composite 1170 15% L-cell large, can be tested with the tensile strength 31.92 MPa and another composite 45A 10% α­-cell large, had the longest elongation at break 1279.23%. After the formulation of composites, the 4 finally shortlisted composites in Stage 3 were 3D printed into a fabric with a self-designed DIY pellet extruder 3D printer. Those fabrics were also further evaluated the fabric performance with ball burst test, tensile test and fabric elasticity. Those results can be a reference and compared to commercial fabric. The newly developed TPU / cellulose composites were successfully 3D printed in a fabric form. It shows the high feasibility of 3D printing an apparel product with high performance flexible material, which contains bio-based ingredients, and less wastage will be generated because of 3D printing, as the benefit.