This paper presents the development of wood flour (WF)-filled polylactic acid (PLA) composite filaments for a fused deposition modeling (FDM) process with the aim of application to 3D printing. The composite filament consists of wood flour (5 wt %) in a PLA matrix. The detailed formulation and characterization of the composite filament were investigated experimentally, including tensile properties, microstructure, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The feedstock filaments of this composite were produced and used successfully in an assembled FDM 3D printer. The research concludes that compared with pure PLA filament, adding WF changed the microstructure of material fracture surface, the initial deformation resistance of the composite was enhanced, the starting thermal degradation temperature of the composite decreased slightly, and there were no effects on the melting temperature. The WF/PLA composite filament is suitable to be printed by the FDM process.

No abstract

No abstract

For designing and fabricating personalized, cost-effective and biodegradable orthoses, a finger orthosis was chosen as an example to explore a suitable material, personalized design method, and fabrication with a fuse-deposition-modeling (FDM) open-source 3D printer. Thermoplastic polyurethane (TPU)/polylactic acid (PLA) composite filaments were explored for 3D printing. The polymer composite compositions were TPU/PLA: 0 %/100 % (TP0), 25 %/75 % (TP25), and 50 %/50 % (TP50) by weight, respectively. The mechanical performance, thermal properties, and structure of the TPU/PLA composite filaments were assessed by tensile tests, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and powder X-ray diffraction (XRD) measurements. Compared to the neat PLA, the TP25 specimens exhibited almost the same tensile strength, but its higher elongation at the break indicates that TP25 is more suitable for the material of orthoses. However, a further increase of the TPU ratio to 50 % resulted in a sharp decrease of the tensile strength. The addition of TPU had little effect on the starting thermal decomposition temperature, glass-transition temperature, and melting temperature of the composites. The composite filaments can be printed through the normal 3D printing procedure. 3D scanning and open-source 3D printers can be used to complete the design and fabrication of personalized orthoses.

Open source 3D printers (OS3DPs) have become increasingly more widespread in recent years because of their ease of use and budget friendliness, with the majority being fused deposition modeling (FDM) printers. However, due to natural deficiencies of the FDM printing methodology, different printing parameters can cause various properties of printed parts. To obtain printed polylactic acid (PLA) parts with improved tensile properties, a tension model of the part and an orthogonal experiment scheme were constructed in this paper. The effects of three printing parameters (layer height, orientation angle (OA) of the part, and print speed) on tensile properties (elastic modulus, tensile strength, and elongation at break) were investigated. The results demonstrated that the printing parameters affected the tensile properties of PLA parts. Larger layer height and lower print speed contributed to the improvement of tensile strength. The OA of the part had the greatest effect on the parts’ elastic modulus and elongation at break among the three parameters. Both layer height and OA of the part affected part tensile strength significantly. In this research, layer height of 0.2 mm and print speed of 20 ~ 30 mm/s are found to be the optimal printing parameters. Adjusting the OA of the part can provide targeted tensile properties, and the parts with the OA of 45° resulted in the lowest tensile strength because the tensile force is only held by fibers parallel to the force orientation instead of all fibers.

Rigid polyurethane (PUR) foam is one of the most important insulating materials used today in the construction industry and is the main insulation material used in the global appliances industry. This study developed rice straw fiber-filled PUF (RPUF) and wheat straw fiber-filled PUF (WPUF) and explored the morphology, sound absorption properties, heat transfer, and compressive strength of the PUF composites. The results indicated that, with the higher fiber content, more open cells were observed in SEM images of the composites. The average sound absorption coefficients (ASAC) of both WPUF and RPUF were significantly increased when 5 per hundred polyols (php) by weight and 10 php fiber contents were added. When fiber contents of 15 php and 20 php were utilized, ASAC reduced due to the tortuosity of cells and large holes in the foam. The sound absorption coefficient (SAC) first increased, then decreased, and increased finally as the sound frequency increased from 100 to 2000 Hz for the two composites. The thermal conductivities of both WPUF and RPUF first decreased and then increased as the fiber content increased from 0 to 20 php. When 5 and 10 php straw contents was added, the thermal conductivities were reduced by 25% to 50% compared to that of the pure PU form (0 php), indicating that the improved thermal insulation ability was obtained. The composite compressive strength was reduced by 19% to 28% due to the fiber addition.

Wood-based materials in current additive manufacturing (AM) feedstocks are primarily restricted to the micron scale. Utilizing large-scale wood in existing AM techniques remains a challenge. This paper proposes an AM method—laser-cut veneer lamination (LcVL)—for wood-based product fabrication. Inspired by laminated object manufacturing (LOM) and plywood technology, LcVL bonds wood veneers in a layer-upon-layer manner. As demonstrated by printed samples, LcVL was able to retain the advantageous qualities of AM, specifically, the ability to manufacture products with complex geometries which would otherwise be impossible using subtractive manufacturing techniques. Furthermore, LcVL-product structures designed through adjusting internal voids and wood-texture directionality could serve as material templates or matrices for functional wood-based materials. Numerical analyses established relations between the processing resolution of LcVL and proportional veneer thickness (layer height). LcVL could serve as a basis for the further development of large-scale wood usage in AM.

No abstract