This study presents the physicochemical and mechanical behavior of incorporating hydroxyapatite (HAp) with polylactic acid (PLA) matrix in 3D printed PLA/HAp composite materials. Effects of powder loading to the composition, crystallinity, morphology, and mechanical properties were observed. HAp was synthesized from locally sourced nanoprecipitated calcium carbonate and served as the filler for the PLA matrix. The 0, 5, 10, and 15 wt. % HAp biocomposite filaments were formed using a twin-screw extruder. The resulting filaments were 3D printed in an Ultimaker S5 machine utilizing a fused deposition modeling technology. Successful incorporation of HAp and PLA was observed using infrared spectroscopy and X-ray diffraction (XRD). The mechanical properties of pure PLA had improved on the incorporation of 15% HAp; from 32.7 to 47.3 MPa in terms of tensile strength; and 2.3 to 3.5 GPa for stiffness. Moreover, the preliminary in vitro bioactivity test of the 3D printed PLA/HAp biocomposite samples in simulated body fluid (SBF) indicated varying weight gains and the presence of apatite species’ XRD peaks. The HAp particles embedded in the PLA matrix acted as nucleation sites for the deposition of salts and apatite species from the SBF solution

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Utilization of natural biopolymers has shown potential in generating innovations for tissue engineering applications. This study aims to fabricate scaffolds from cellulose acetate derived from kapok fiber. Cellulose is extracted from raw kapok fibers by alkali treatment and delignification then synthesized into cellulose acetate. Kapok cellulose acetate (KCA) is dissolved in dimethyl sulfoxide to fabricate the scaffold. Materials were characterized using Attenuated Total Reflectance – Fourier Transform Infrared (ATR-FTIR) spectrometer, X-ray diffractometer (XRD) and Differential Scanning Calorimeter (DSC). FTIR analysis has shown that cellulose was extracted from kapok and cellulose acetate was successfully synthesized. XRD analysis also confirmed the presence of cellulose acetate. Results have also shown that synthesized KCA seems to have higher crystallinity than commercially available cellulose acetate (CCA). The degree of substitution (DS) of KCA was found to be 2.85 which is close to the DS value of tri-substituted cellulose acetate. DSC analysis has shown lower glass transition temperature of 52.15°C but higher degradation temperature of 300.43°C than the CCA. Moreover, the values for the enthalpy of fusion for two endotherms of KCA (44.0556 J/g and 18.6946 J/g) are higher than the values for CCA by 344% and 261%, respectively; thus, indicating the higher degree of crystallinity for synthesized KCA samples.

This study aims to demonstrate the effects of various stacking sequences of different glass fiber architecture forms on the mechanical properties of glass fibre reinforced polyester composites. The composites were manufactured by hand lay-up technique and its mechanical properties were characterized in terms of tensile, flexural, and drop-ball impact tests as well as water absorption. The mechanical properties of the glass fiber reinforced polyester were somewhat affected depending on the stacking sequences from single alternating order, double alternating order, and triple alternating order of chopped strand mat and plain-woven fabric piled in ten (10) to fourteen (14) layers. The laminates consisting of alternating sequence manner of plain-woven fabric and chopped strand mat stacked in different layers have no significant effect on the mechanical properties. Stacking sequence of double alternating layer piled in twelve (12) layers was found to have better tensile strength than single and double alternating order of two different glass fiber form while the triple alternating manner piled in twelve (12) layers resulted to higher tensile modulus. The double alternating order of different glass fiber forms stacked in twelve (12) layers resulted to an improvement in flexural properties. Some selected laminates exhibited no delamination in drop-ball impact test and minimal water absorption when immersed in water for 30 days for all the laminates.

In an attempt to improve the physical properties of 3D printed poly lactic acid (PLA), this study aims to develop a microcrystalline cellulose fiber and observe the effects of fiber loading on the PLA/cellulose composites to the composition, crystallinity, morphology, and tensile properties of the resulting 3D printed material. Microcrystalline cellulose (MCC) have been extracted from indigenous raw abaca fibers and used as the fiber reinforcement for the PLA matrix. Composites of 1 and 3 wt% MCC fibers with PLA were processed using the twin-screw extruder to produce filaments. The resulting composite filaments were 3D printed utilizing the fused deposition modeling technology. FTIR, XRD, digital microscopy, and mechanical testing were used in characterizing the various 3D printed PLA/MCC composite. With the incorporation of cellulose, the PLA/MCC had up to 32% increase in tensile strength and 43% increase in modulus at just 3 wt% fiber loading due to the inherent high modulus of abaca cellulose. The MCC significantly influences the chemical, structural and mechanical properties of the 3D printed PLA/MCC composites.

Functionally graded additive manufacturing (FGAM) is a fused deposition modeling (FDM) technique that steadily varies the ratio of the material distribution in a single specimen depending on a specific function. The gyroid design is used in a variety of applications because of its high porosity, surface area, and its good mechanical properties. This work investigated the relationship between the geometric design and the mechanical performance of the acrylonitrile butadiene styrene (ABS) gyroid structure using FDM. Tensile, compression, and flexural tests were performed to determine the mechanical behavior of the functionally graded lattice structures with controlled infill densities per layer. Results showed that the performance of the ABS gyroids is dominated by their geometrical design. The tensile strength of the single-layered structure increased linearly with respect to the increase in infill density from 15% to 35% however, compression and flexural results from 25% to 35% showed an exponential increase of 175.52% and 112.14%, respectively. Increasing the outer layer density from 15% to 35% for the three-layered structures resulted in an increase in tensile strength up to 62%. It was observed that the three-layered structures having the same amount of infill densities provided similar mechanical behavior in all the tests conducted. Fracture failures occurred in the adjoining layers wherein the density of the interconnected structures is a function of its material distribution.

This study investigates the relationships between the composition, cell wall microstructure, and mechanical properties of the abaca fiber. Raw abaca fibers have undergone a series of sequential chemical treatments (acetone/methanol, boiling water, EDTA, HCl, NaClO2, and NaOH) to selectively remove certain non-cellulosic components (NCCs) in the fiber, such as waxes, water-soluble fragments, pectin, and lignin in a step-by-step manner. Changes in composition, morphology, and mechanical properties were observed using FTIR spectroscopy and ion chromatography, digital microscope and SEM, and tensile tests, respectively. The raw fiber was composed of 23% NCCs, 18% hemicellulose, and 58% cellulose, and exhibited a 17.4 GPa Young’s modulus and a 444 MPa tensile strength. Furthermore, the raw abaca fibers demonstrated a linear tensile graph without yielding, and a planar fracture surface without fiber pull-outs, thus suggesting a highly elastic but brittle nature. At the end of the alkali treatment, the fibrillated fiber was 83% cellulose, yet the stiffness and strength dropped to 7.3 GPa and 55 MPa, respectively, as more components were removed, and microfibril relaxation and realignment have occurred. Load-bearing cellulose and hemicellulose accounted for 42% and 36% of the stiffness, respectively, due to –OH groups capable of hydrogen bonding. 63% of the strength was due to thenative NCC matrices, which contribute a significant role within the cell wall’s load-transfer activities.

Metal oxide semiconductors such as cobaltous oxide (Co3O4) and cuprous oxide (Cu2O) have caught the attention of many researchers due to their wide variety of applications. The attachment of Cu2O to Co3O4 was assisted by polyethylene glycol and the nanostructuring by ultrasonic sound. X-ray Diffraction (XRD) analysis of the fabricated composite reported characteristic peaks for crystalline Co3O4 and Cu2O. Results from Energy Dispersive X-ray (EDX) Spectroscopy showed the presence of cobalt, copper, and oxygen atoms which supports the result obtained in XRD. Cauliflower to nearly spherical shaped Cu2O - Co3O4 nanostructures were formed as observed in the Scanning Electron Micrographs (SEM) with a mean diameter of 0.5-1.0 μm. the shape of the composite and its surface morphology was altered with the use of different precursor materials for the synthesis of the Co3O4 seed. A blue shift in the UV-vis was observed upon the use of nitrate based precursor indicating the presence of smaller and finer particles in the composite. Overall results prove that Cu2O and Co3O4 can be synthesized using a facile solution approach with the aid of PEG and ultrasonic sound its application in the field of photocatalysis is probable.