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.
Agricultural biomass residues are emerged from harvesting and processing of agricultural crops. When the crop production increases, a large amount of biomass residues is produced and remained after ...cutting of peel, bunch, straw and stalk of crops. In this work, agricultural biomass residues (cassava rhizome, durian peel, pineapple peel and corncob) were selected as feedstock for carbon-rich biochar (CRB) production using a facile pyrolysis method. Proximate analysis and thermogravimetric analysis (TGA) were used to characterize biomass feedstock. The results showed that the percentage of fixed carbon in biomass feedstock ranged between 11.91% and 17.51%. Characteristic differences of the CRB were investigated using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The carbon content in the CRB was found to significantly depend on biomass origin. Interestingly, cassava rhizome, which has a higher percentage of fixed carbon, is a superior precursor for CRB production. The study of different pyrolysis temperature indicated that the carbon content of cassava rhizome derived CRB is increased with pyrolysis temperature. The tensile properties of composite between poly(lactic acid) PLA and different types of biomass-derived CRB were investigated. PLA composite incorporated with a higher carbon content-CRB tended to exhibit improved mechanical properties. Specifically, the elastic modulus and impact energy of PLA/CRB composite specimens increased remarkably with the incorporation of CRB powder. The current research indicates that CRB prepared from agricultural biomass residues could be a sustainable material for utilization in PLA biocomposites.
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•Cassava rhizome, Durian peel, Pineapple peel and Corncob were analyzed for physical properties and pyrolysis behaviors.•Cassava rhizome were difficult to be decomposed but their carbon content was higher than other agricultural biomass residues.•Carbon content in carbon-rich biochar (CRB) was found to significantly depend on biomass origin and pyrolysis temperature.•Carbon content in CRB affects to mechanical properties (tensile elastic modulus and impact energy) of PLA/CRB composites.
Poly(lactic acid) (PLA) is one of the most promising biopolymers extensively used in food, packaging, medical and pharmaceutical industries. It is due to favorable physicochemical properties, in‐situ ...hydrolytic degradation and well‐established processing parameters. However, in medical engineering applications, PLA shows some drawbacks like low cell adhesion, biological inertness, slow degradation rate and high acid inflammation. These shortcomings of pure PLA could be addressed by blending it with other bioresorbable materials and compatibilizers. This review provides comprehensive information on different PLA composites in the field of tissue engineering, implants, injury management and drug delivery systems. The PLA‐based composites are divided into four parts: PLA/polymer, PLA/metal, PLA/ceramic, and PLA/nanoparticles. It also investigates various synthesis process, role of different compatibilizers, in vitro studies and their in vivo applications.
Highlights
Review the trends of bioresorbable PLA blends/composites.
Extensively focused on PLA blend with polymer, metal, ceramic, and nanoparticles.
Role of reinforcement and compatibilizer to overcome shortcomings of PLA implant.
Highlights advantages, limitations, and properties of different types of PLA implants.
Discuss various clinical applications and future of PLA blends/composite scaffolds.
Different types of bioresorbable PLA composite
Jute fiber with high content and large aspect ratio is directly used to prepare PLA composites to show the effect on structure and properties. By comparing with bamboo powder, it is found that the ...large aspect ratio of jute fiber is helpful to form a crisscross structure in PLA composites to provide a strong framework. And the larger amount of jute fiber leads to the stronger framework in the PLA composites. Accordingly, the high comprehensive mechanical properties are produced of the PLA composites with jute fiber. Only through the simple blending of 70% jute fiber and PLA, the flexural strength and flexural modulus respectively reach 94.0 ± 4.4 MPa and 9116.7 ± 127.2 MPa, which obviously exceed the mechanical properties of PLA/bamboo blends. The addition of jute fiber also improves the thermal resistance of PLA composites as well as the crystallization ability and perfection of PLA. All the results exhibit the advantages of high content filling of jute fiber with large aspect ratio to modify PLA. Utilization of biomass filler with high content and large aspect ratio will provide an important methodology to expand the application capacity of fully degradable composites in many areas.
Jute fiber with high content and large aspect ratio is directly used to prepare PLA composites. Accordingly, a crisscross structure is formed in PLA composites to provide a strong framework. With the addition of 70% jute fiber in PLA composite, the flexural strength and flexural modulus respectively reach 94.0 ± 4.4 MPa and 9116.7 ± 127.2 MPa.
The tensile strength and modulus of elasticity of a jute/polylactic acid (PLA) composite were found to vary nonlinearly with the loading angle of the specimen through the tensile test. The variation ...in these properties was related to the fiber orientation distribution (FOD) and fiber length distribution (FLD). In order to study the effects of the FOD and FLD of short fibers on the mechanical properties and to better predict the mechanical properties of short-fiber composites, the true distribution of short fibers in the composite was accurately obtained using X-ray computed tomography (XCT), in which about 70% of the jute fibers were less than 300 μm in length and the fibers were mainly distributed along the direction of mold flow. The probability density functions of the FOD and FLD were obtained by further analyzing the XCT data. Strength and elastic modulus prediction models applicable to short-fiber-reinforced polymer (SFRP) composites were created by modifying the laminate theory and the rule of mixtures using the probability density functions of the FOD and FLD. The experimental measurements were in good agreement with the model predictions.
The present study focuses on development and characterization of nano‐SiO2 reinforced wood flour reinforced polylactic acid (PLA) composite. The detail characterization involves the physical ...characterization such as stimulus response behavior, mechanical characterization such as hardness, tensile strength, flexural strength, impact strength, and so forth, and thermal characterization such as thermal stability and thermal conductivity. The finding of results indicates that the shape memory recovery rate and recovery ratio are increased with the increase in temperature. On adding 2 wt% of nano‐SiO2, micro‐hardness, flexural strength, impact strength are increased by 35%, 25.4%, 32.6% respectively. Whereas, on adding 5 wt% of wood flour, micro‐hardness, flexural strength are increased by 17%, 4.4%, 15% respectively. On the other hand, tensile strength is decreased with the addition of wood flour and nano‐SiO2. In addition, increase in wood flour increases the shape recovery rate whereas increase in nano‐SiO2 decreases the shape recovery rate. In thermal analysis, increase in wood flour and nano‐SiO2 content improves the thermal degradation temperature. On the other hand, addition of wood flour and nano‐SiO2 decreases the thermal conductivity of PLA composite.
Polylactic acid (PLA) filament 3D parts printed by fused deposition modeling (FDM) have poor mechanical properties because of weak fusion interfaces. This article shows that SiC-coated PLA filaments ...are effective means to increase mechanical performance of PLA composites that are microwave heated. Numerical calculations on temperature-rising characteristics and temperature distribution of the interface in the microwave field are shown. 3D-printed specimens of PLA/SiC composites were printed by FDM and heated in a microwave. The experiments show the SiC/PLA composite filaments have better temperature-rising characteristics and temperature distribution at 185 °C for 60 s in the microwave field, and this enabled the 3D-printed specimens to achieve in situ remelting on the interface and increased interface bonding between PLA filaments. The SiC/PLA composite specimens heated using microwave increased by 51% in tensile strength, 42% in tensile modulus, and 18.7% in interlayer breaking stress relative to PLA. These results provided a new approach for the improvement of FDM workpiece strength.
A novel and economic device is developed for simulating the physiological mechanochemical conditions. The degradation behaviors of poly-lactic acid (PLA) based composite reinforced with magnesium ...alloy wires (Mg wires/PLA) under dynamic compression and bending loads are investigated. The results denote the dynamic loads significantly influence the degradation behaviors of the composite. The dynamic bending load would profoundly promote the degradation of Mg wires in the composite and then accelerate the mechanical properties loss of the composite. The bending strength retention of the composite under consistent dynamic bending load at a magnitude of 5.6 N (about 5.6 MPa for the maximum stress at the middle surface) after 21 days immersion is about 53.3%, comparing to 69.7% for the dynamic compression load at a magnitude of 12 N (0.5 MPa for the compression stress). Furthermore, a numerical model is successfully postulated to elucidate the bending strength evolution of the composite under different dynamic loading conditions.
Low-cost, compostable, high-efficiency photothermal conversion materials with shaping freedom into complex geometrical structures have received considerable attention by the photothermal conversion ...technologies. In this study, a kind of bio-based filament with photothermal conversion function for fused filament fabrication (FFF) technology was prepared by adding hazelnut shell carbon (HSCs) in polylactic acid (PLA) matrix. The HSCs were obtained at 300, 500, 700, and 900 °C. The results revealed that the morphology, particle size, pore structure, surface functional groups, and degree of graphitization of HSCs varied with the pyrolysis temperature. Additionally, the three-dimensional (3D) printability of PLA-HSC composite filaments as well as the photothermal performance of the printed structures were affected by the pyrolysis temperature of HSCs. All PLA-HSC filaments were suitable for 3D printing besides HSC pyrolyzed at 300 °C. Furthermore, the fluidity of the composites increased with the pyrolysis temperature of HSCs. The rheology results demonstrated that the complex viscosity, storage modulus, and loss modulus decreased with the increase of pyrolysis temperature. However, the mechanical properties and the thermal stability of the PLA-HSC filaments showed opposite trend. At the wavelength range of 250–2500 nm, with HSCs pyrolyzed at 700 and 900 °C, the 3D printed PLA-HSC parts demonstrated excellent photothermal performance with a light absorption intensity of around 93 %. Overall, HSCs pyrolyzed at 700 °C is the most cost-effective candidates for the preparation of PLA-based filament for photothermal conversion components. In this work, a brine evaporation crystallizer was 3D printed to demonstrate the application of this filament.
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