The fluorinated treatment coating (MgF2), polylactic acid (PLA) coating, and composite coating (MgF2/PLA) were prepared on biodegradable Mg-2.2Zn-0.3Ca alloy wires to improve the corrosion ...properties. The composition characteristics and microstructure of the samples were investigated by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS). The corrosion resistance of all samples were investigated by immersion tests and electrochemical techniques in vitro simulated body fluid (SBF). The results indicated single MgF2 and PLA coating performed opposite protective behaviors in the short and long term immersion tests. The corrosion rate of MgF2-coated samples was lower than that of PLA-coated samples, but the corrosion fracture lifetime of MgF2-coated samples was shorter than that of PLA-coated samples. The MgF2/PLA composite coating exhibited superior short and long term protective effect for Mg wires. These results exhibit that single MgF2 or PLA coating cannot behave strong anti-corrosion ability, only the MgF2/PLA-coated Mg-2.2Zn-0.3Ca alloy wires has high corrosion resistance in vitro immersion, and it has promising potential for surgical implant applications.
•Short term protective effect of the coating is not equivalent to that of long term on Mg alloy wires surface.•Single MgF2-coating and PLA-coating display opposite anti-corrosion behavior and cannot protect Mg wires effectively.•MgF2/PLA-coated Mg alloy wires exhibit superb the short and long term corrosion resistance due to the synergistic effect.
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•4D printed PBS/PLA filament was first developed.•The graphene oxide (GO) functionalized shape memory PBS/PLA porous scaffold can be actuated by near-infrared (NIR) laser, enabling ...dynamic, remote, and accurate control of the 4D transformation process.•Various complex architectures (e.g. starfish, aneurysm model) were high-quality printed using 4D printing PBS/PLA filament.•4D printing PBS/PLA filament with outstanding shape memory performance exhibited a promising prospect in the biomedical field.
4D printing adds time as the fourth dimension to 3D printing, which has been actively explored in the biomedical field to develop patient-specific implants due to the ease of manufacturing complex architectures and the capability of dynamic transformations. However, the 4D printing filament used for fused deposition modeling (FDM) is quite limited. Here, 4D printing shape memory polybutylene succinate/polylactic acid (PBS/PLA) composite filament is prepared. The mechanical properties, surface morphology, and shape memory performances of the printed specimens are investigated. Besides, graphene oxide functionalized PBS/PLA shows attractive photothermal properties under near-infrared (NIR) irradiation, and a dynamic, remote, and accurate controlled 4D transformation of a porous scaffold is exhibited. As the first demonstration of 4D printing filament of PBS/PLA for FDM, this work shows its promising application prospects in tissue engineering, photothermal therapy, etc. Additionally, NIR-triggered 4D transformation solves the problem that the conventional thermal-trigger transformation process is difficult to control.
The main objective of this paper is to investigate the mechanical performance of the continuous carbon fiber reinforced PLA composites (CFRPCs) printed in vacuum. A novel 3D printer which is used to ...manufacture CFRPCs in vacuum and a continuous carbon fiber prepreg filament production equipment which is used to produce the raw materials needed for 3D printing are first proposed. Compared with the printing in atmospheric environment, the impregnation effect of the part printed in vacuum can be effectively improved, the porosity is reduced from 13.93% to 4.18%, and the flexural strength and modulus are increased by 24.51% and 8.35%, respectively. The influences of 3D printing process parameters on the mechanical properties of the specimens printed in vacuum are systematically researched. The flexural properties of the specimens are positively correlated with the printing temperature and inversely related to the printing speed and layer thickness. When the printing temperature increases from 180 °C to 230 °C, the flexural strength and flexural modulus of the printed parts are increased by 45.73% and 31.75%, respectively. The feasibility of 3D printing continuous carbon fiber reinforced thermoplastic (CFRTP) in vacuum is demonstrated.
In this study, modified TiO2 grafted flax fibers were used to reinforce PLA composites. The fibers were oxidized in order to improve the interfacial adhesion of the fibers to TiO2 film. The TiO2 film ...was created on the flax fiber by a Sol-Gel dip-coating technique. The interfacial adhesion of the fibers to the matrix was investigated qualitatively by microscopy, and quantitatively by measuring inter-laminar shear strength. Impact and tensile tests characterized the mechanical properties of the modified TiO2 grafted flax fiber reinforced composites. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Dynamic mechanical analysis (DMA) were used to reveal the thermal and thermo-mechanical behavior of the composites. The hygroscopic behaviors of the composites were determined by the water uptake assessment. The results showed statistically significant increase in adhesion bonding of the modified fibers to the matrix. The modified TiO2 grafted flax fibers increased the impact resistance of pure PLA by three times. The microscopic observations verified the modifications in the mechanical and physical properties of the composites. Moreover, the amount of water sorption decreased by 18% in the modified TiO2 grafted fiber reinforced composite.
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•The thickness of the TiO2 film was 143±29nm, and 380±25nm for non-oxidized, and oxidized flax fibers respectively•The cellulose oxidation prior to TiO2 grafting increased the interfacial adhesion of the fiber to the film.•The impact resistance of the composites increased by at least three times more than pure PLA.•The amount of water sorption decreased by 18% in the modified fiber reinforced composites.
This present study focuses on evaluation of mechanical properties of three dimensional (3D)-printed carbon fiber/polylactic acid (CF/PLA) composites, using fused deposition modeling (FDM) technique. ...The composites were prepared with different slicing parameters: layer heights or thicknesses, infill densities and layer patterns. The 3D-printed composite samples were subjected to tensile, flexural and interlaminar shear strength (ILSS) tests to assess the influence of the process parameters on their mechanical characteristics. Further investigations were carried out to evaluate the effect of surface roughness of the samples. From the test results, it was evident that both rectilinear and hexagonal layer patterns exhibited better mechanical properties at infill density and layer thickness of 60% and 0.64 mm, respectively. The scanning electron microscopy (SEM) images depicted that lesser layer thickness produced poor CF/PLA interfacial bonding and major failure mode was traced to fiber pull-out. Therefore, engineering application of the composite samples depends on their slicing parameters.
Pyrophyllite (Prl), an aluminosilicate with a balanced mineral structure and extremely small particle size, appears to be an ideal filler but is rarely used in polymers. Herein, a method for the ...application of pyrophyllite in polymers is reported. A multifunctional filler is prepared by epoxy‐modified pyrophyllite and incorporated into poly(latic acid) (PLA) to enhance its processability and crystallization properties. Results show the effectiveness of epoxy‐modified Prl in composite film with a significant reduction in glass transition temperature, and noteworthy increment in crystallinity and spherulite growth rate. Water vapor barrier properties of PLA composite films increase over 30% with a range of Prl Loading. Furthermore, an enhancement of the tensile strength is increased by 30% and strain at break by 337.1% for PLA composite films compared to neat PLA. This work provides a new idea to prepare the functionalized pyrophyllite fillers and a theoretical basis to develop the application of pyrophyllite for polymers.
A multifunctional filler is prepared by epoxy‐modified pyrophyllite and incorporated into PLA to enhance its processability and crystallization properties. This work provides a new idea to prepare the functionalized pyrophyllite fillers and a theoretical basis to develop the application of pyrophyllite for polymers.
In this article, polylactic acid-based composites reinforced with 5% of polyethylene, iron, and magnesium powders were prepared by extrusion and compressed under the pressure of about 10 MPa and ...characterized. These composites were mechanically, thermally, and morphologically evaluated. It was found, compared to the pure polylactic acid (PLA), an improvement in tensile strength (both σ and YS
) was obtained for the composite with the iron powder addition, while the magnesium powder slightly improved the ductility of the composite material (from 2.0 to 2.5%). Degradation studies of these composites in the 0.9% saline solution over a period of 180 days revealed changes in the pH of the solution from acidic to alkaline, in all samples. The most varied mass loss was observed in the case of the PLA-5%Mg sample, where initially the sample mass increased (first 30 days) then decreased, and after 120 days, the mass increased again. In the context of degradation phenomenon of the tested materials, it turns out that the most stable is the PLA composite with the Fe addition (PLA-5%Fe), with highest tensile strength and hardness.
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