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
Replacement of ethanol‐water solutions (70 – 100% v/v) with deionized water was performed in a flow cell of a particle size analyzer. The resulting alcohol solutions were found to contain bulk nanoscale bubbles due to air supersaturation as can be induced by the difference in gas solubility of the solvents. The effect of charged and polar solutes (salt and sugar) that may influence the formation and surface chemistry of nanobubbles was also determined. Dispersion characteristics such as hydrodynamic diameter, particle concentration, along with the particle‘s electrokinetic property were measured all at once using light scattering techniques after solution replacement with and without the solute species. Light scattering results showed that the resulting solutions upon exchange have higher particle quantities than the starting ethanol‐water solvents with smaller diameters ranging from 80 to 160 nm due to nanobubble formation. The claim for air supersaturation forming nanobubbles that may have resulted to the increase in particle density can also be deduced from the obtained optical images in a microscope. The electrokinetic potential or zeta potential was also higher for the solvent exchange protocols entailing for a selective orientation of ethanol molecules in a bubble surface. More importantly, In terms of solute effects, it appears that while salt anions promote gaseous diffusion, sugar molecules inhibit it.
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