In this work, fused deposition modeling (FDM) technology was used to prepare poly(lactic acid)/walnut shell/hydroxyapatite (PLA/WS/HA) composite filaments. HA was treated with silane and characterized by Fourier transform infrared spectroscopy (FTIR). The composites were investigated by using simultaneous thermal analyzer, scanning electron microscopy (SEM) and a universal mechanical testing machine. The results showed that incorporating either HA or WS improved the thermal stability and water absorption of PLA, but lowered the tensile and compression strength. Fillers toughened the PLA matrix, resulting in higher tensile elongation and compressive strain. The tensile and compressive strengths of samples significantly dropped after water-immersion for 6 weeks. Finally, scaffolds were manufactured by using FDM. The compression modulus and structural feature of scaffolds indicated that the PLA/WS/HA composites have the potential to be applied in structural parts, such as bone implants.

In this work Macadamia nutshell (MS) was used as filler in fused deposition modeling (FDM) of Poly (lactic acid) (PLA) composites filaments. Composites containing MS both treated and untreated with alkali and silane were investigated by means of Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), Thermogravimetry (TG), scanning electron microscopy (SEM). The results showed that the treated MS composites had better thermal stability. Furthermore, compression tests were carried out. The PLA with 10 wt% treated MS composite was found possessing the best mechanical properties which was almost equivalent to that of the pure PLA. Finally, porous scaffolds of PLA/10 wt% treated MS were fabricated. The scaffolds exhibited various porosities in range of 30–65%, interconnected holes in size of 0.3–0.5 mm, micro pores with dimension of 0.1–1 μm and 37.92–244.46 MPa of elastic modulus. Those values indicated that the FDM of PLA/MS composites have the potential to be used as weight lighter and structural parts.

In this work, four kinds of nutshells (including walnut, almond, macadamia and wild almond shell powder (WSP, ASP, MSP and WASP) were composed with poly (lactic acid) (PLA). Fused deposition modeling technology was used to prepare the PLA/nutshell composite filaments. Nutshells were investigated by means of Fourier transform infrared spectroscopy regardless of the treatment with alkali. The composites were characterized by using: differential scanning calorimetry, thermogravametric, scanning electron microscopy. Meanwhile, the water-resistance and tensile properties were examined. The results showed that the thermal stability, water-resistant ability and tensile properties of untreated composites got worse comparing with that of PLA, but were enhanced dramatically after NaOH treatment. PLA/treated WASP has the highest degradation temperature. The crystallization degree of PLA/treated MSP and PLA/treated WASP was improved, when compared with that of PLA. The tensile strengths of PLA/MSP-Na and PLA/WASP-Na were almost close to that of PLA. PLA/MSP composite was the most water-resistant regardless of surface treatment. Those results indicated that the four kinds of composites have a potential application to manufacture structural parts with lighter weight.

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This paper interweaved scaffolds with poly(ether ether ketone) (PEEK) and poly(lactic acid)/Walnut shell/hydroxypatite (PLA/WS/HA) composites by using fused filament fabrication technology, although there was a huge difference in thermal property term between PLA and PEEK. In order to keep mechanical properties of PEEK scaffold and remedy the stress loss produced by pores, PLA/WS/HA composites were used to fill the pores with gradient form outside-in (0.4-0.8 mm, 0.6-1.0 mm, 0.8-1.2 mm and 1.6-2.0 mm). The thermal stability, tensile and compression properties, tensile fracture surface morphology, cytotoxicity and in vivo experiment were investigated. The results showed: the scaffolds were intact without any flashes and surface destruction, and kept a well thermal stability. Compared with the PEEK porous scaffolds, the tensile fracture stress and strain, compression yield stress and strain of interweaved scaffolds were dramatically enhanced by 24.1%, 438%, 359.1% and 921.2%, respectively, and they climbed to the climax at 8 wt% of WS. In vivo experiment showed that the degradation of PLA/WS/HA composites synchronized with the adhesion, proliferation and ingrowth of bone cells, keeping the stable biomechanical properties of interweaved scaffolds. Those experiments showed that interweaved PEEK-PLA/WS/HA scaffolds had the potential to be used as bone implant in tissue engineering.

In this work, willow fiber was extracted from willow inner bark and modified with alkali solution of various concentrations, temperature and time. The morphology, surface functional group, crystal and thermal stability were investigated by using a scanning electron microscopy, a Fourier transform infrared spectroscopy, an X-ray powder diffractometer, and a simultaneous thermal analyzer, respectively. The acid (H2SO4, 2 ml/l) extraction procedure removed the hemicellulose and part of lignin from willow bark, cleared the aggregation of WB, kept the crystal structure of willow fiber, dramatically increased the crystal length of fiber (from 18.46 to 30.15 nm), and enhanced the onset degradation temperature (from 262.23℃ to 297.62℃) and chemical reactivity (DTG: from 0.57%/s to 0.84%/s). The alkali treatment further removed lignin from willow fiber, smoothed the fiber surface, increased the intensity of cellulose [Formula: see text] from 646 counts to 1292 counts, and lengthened the crystal length from 30.15 to 41.84 nm. Varying the alkali treating condition, the crystal index and thermal stability reached to the climax at 60℃ of treating temperature and 7 h treating time. The treated willow fiber may have potential applications to composite with polymer, and to be used in pharmaceutical field as additives.

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Abstracts. This work presents the fused deposition modelling of Poly (lactic acid)/sunflower seed husk/montmorillonite (PLA/SSH/MMT) composites filaments. The SSH was treated with NaOH followed by silane. The rheological behavior, thermal stability and the tensile properties were determined. The results showed that the onset temperature at the maximum degradation rate reached to the highest at 5 wt% SSH and 15 wt% MMT. The tensile strength was enhanced to 45.8 MPa by incorporation of 15wt% MMT. The utilization of FDM and SSH reduced the cost of PLA filament by about 35%, and make a good using of the wastes.