Functionalities of 3D printing filaments have gained much attention owing to their properties for various applications in the last few years. Innovative biocomposite 3D printing filaments based on polylactic acid (PLA) composited with ZnO nanoflowers at varying contents were successfully fabricated via a single-screw extrusion technique. The effects of the varying ZnO nanoflower contents on their chemical, thermal, mechanical, and antibacterial properties were investigated using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and tensile testing, as well as qualitative and quantitative antibacterial tests, respectively. It was found that the ZnO nanoflowers did not express any chemical reactions with the PLA chains. The degrees of the crystallinity of the PLA/ZnO biocomposite filaments increased when compared with those of the neat PLA, and their properties slightly decreased when increasing the ZnO nanoflower contents. Additionally, the tensile strength of the PLA/ZnO biocomposite filaments gradually decreased when increasing the ZnO nanoflower contents. The antibacterial activity especially increased when increasing the ZnO nanoflower contents. Additionally, these 3D printing filaments performed better against Gram-positive (S. aureus) than Gram-negative (E. coli). This is probably due to the difference in the cell walls of the bacterial strains. The results indicated that these 3D printing filaments could be utilized for 3D printing and applied to medical fields.
In this work, poly(lactic acid) (PLA) and nano-silver-coated
porous
clay heterostructure (PCH) hybrid films were successfully fabricated
by a twin-screw extruder. Because of the low dielectric constant of
PLA, nano-silver and PCH were employed to enhance the dielectric properties
of PLA, and nano-silver-coated porous clay heterostructures (Ag/PCH)
with different concentrations of Ag were synthesized by the green
process using ascorbic acid as a reducing agent. The results revealed
that 1 wt % of Ag-coated PCH (Ag/PCH1) exhibited the highest dielectric
constant of up to 40. The physical, chemical, thermal, mechanical,
and dielectric properties of pristine PLA and hybrid films were studied.
The results indicated that adding Ag/PCH fillers could enhance the
dielectric properties of hybrid films, increasing the dielectric constant
almost 10 times higher than that of PLA. In addition, Ag/PCH could
reinforce the mechanical properties of PLA. Furthermore, we prepared
biaxially oriented poly(lactic acid) (BOPLA) films with 4 μm
of thickness. The dissipation factor of BOPLA-Ag/PCH was improved,
while the dielectric constant was only slightly decreased. However,
the BOPLA-Ag/PCH showed better dielectric properties than those of
traditional BOPP films. As a result, PLA-Ag/PCH and BOPLA-Ag/PCH hybrid
films derived from poly(lactic acid) as biodegradable polymers with
superior properties can be applied as dielectric films in capacitors.
Silver‐coated polyvinyl alcohol (Ag/PVA) was prepared using 3,4‐dihydro‐3,6‐dimethyl‐1,3‐2H‐benzoxazine as a reducing agent reported in the petty patent of our research group. Ag/PVA22000 is applicable for making solutions and gels. Solutions of Ag/PVA22000 have exhibited antimicrobial properties against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans, while the gels inhibited only S. aureus, B. subtilis, E. coli, and P. aeruginosa. Therefore, the solutions and gels tend to be used in antimicrobial sprays and gel bandages. Moreover, Ag/PVA145000 was able to form hydrogels by gamma‐ray irradiation. Therefore, the hydrogels with the lowest amount of silver were prepared from 5.0 wt.% of Ag/PVA145000 at the 20 kGy of gamma‐ray irradiation. The results illustrated that the hydrogels exhibited antimicrobial properties against S. aureus, B. subtilis, E. coli, and P. aeruginosa. However, no inhibition of C. albicans was observed for any prepared hydrogels.
This research aimed to synthesize magnesium silicate (MgSiO 3 ) used as a support for Ni−Fe cocatalysts in the depolymerization of kraft lignin. Magnesium silicate was prepared by a hydrothermal method, followed by metal solution impregnation to obtain lignin depolymerization catalysts. The catalytic efficiency of kraft lignin depolymerization to valued phenolic compounds was studied by varying the ratios of Ni and Fe on the MgSiO 3 support. Moreover, other factors such as temperature, reaction time, and catalyst recycling affected both the quality and quantity of the products studied. The results illustrated that the catalyst 10Ni10Fe/MS produced all lignin depolymerization products with the highest yield (14.29 wt %) using reaction conditions of 300 °C and 1 h. In addition, the main products were found to be catechol (11.38 wt %), guaiacol (1.51 wt %), and phenol (0.79 wt %). More importantly, the 10Ni10Fe/MS catalyst showed good reusability even after two recycling processes, and the obtained phenol and guaiacol were found to be 0.63 and 1.01 wt %, respectively.
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