A Novel Extrusion for Manufacturing TiBw/Ti6Al4V Composite Tubes with a Quasi-Continuous Reinforced Structure.
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ABSTRACT: The present work introduces a novel extrusion with filler material to produce the high-performance TiBw/Ti-6Al-4V composite tube with a quasi-continuous reinforced structure. A simulation was adopted to study the effect of the filler material on the shape accuracy of the tubes. Based on the simulation results, the flow stress of the filler material was not the important factor, but the friction coefficient between the filler and TiBw/Ti-6Al-4V composite and the canning shape were critical to the tube precision. The microstructure and mechanical performance for the as-extruded TiBw/Ti-6Al-4V composite tubes were systematically investigated. After extrusion, the transverse section microstructure of the TiBw/Ti6Al4V composite tube remained quasi-continuous and the TiBw were rotated to align the extrusion direction. Moreover, the tensile strength and elongation reached 1240 MPa and 13.5%, resulting from dynamic recrystallization and whisker rotation.
Project description:Semi-aromatic poly (hexamethylene terephthalamide) (PA6T) oligomer (prePA6T) ultrafine powder, with a diameter of <5 μm, was prepared as an emulsion sizing agent to improve the impregnation performance of CF/PA6T composites. The prePA6T hyperfine powder was acquired via the dissolution and precipitation "phase conversion" method, and the prePA6T emulsion sizing agent was acquired to continuously coat the CF bundle. The sized CF unidirectional tape was knitted into a fabric using the plain weave method, while the CF/PA6T laminated composites were obtained by laminating the plain weave fabrics with PA6T films. The interfacial shear strength (IFSS), tensile strength (TS), and interlaminar shear strength (ILSS) of prePA6T-modified CF/PA6T composites improved by 54.9%, 125.3%, and 120.9%, respectively. Compared with the commercial polyamide sizing agent product PA845H, the prePA6T sizing agent showed better interfacial properties at elevated temperatures, especially no TS loss at 75 °C. The SEM observations also indicated that the prePA6T emulsion has an excellent impregnation effect on CF, and the fracture mechanism shifted from adhesive failure mode to cohesive failure mode. In summary, a facile, heat-resistant, undamaged-to-fiber environmental coating process is proposed to continuously manufacture high-performance thermoplastic composites, which is quite promising in mass production.
Project description:Many types of consumer-grade packaging can be used in material extrusion additive manufacturing processes, providing a high-value output for waste plastics. However, many of these plastics have reduced mechanical properties and increased warpage/shrinkage compared to those commonly used in three-dimensional (3D) printing. The addition of reinforcing materials can lead to stiffer parts with reduced distortion. This paper presents work in the reinforcement of recycled polypropylene using cellulose waste materials to generate a green composite feedstock for extrusion-based polymer additive manufacturing. Recycled polypropylene/waste paper, cardboard, and wood flour composites were made using a solid-state shear pulverization process. Fourier transform infrared and thermogravimetric analysis were utilized to qualitatively analyze the amount of filler incorporated into the 3D-printed materials. Recycled polymer composites had increased levels of filler incorporated in the printed parts compared to the virgin polymer composites based on the thermal gravimetric analysis. The dynamic mechanical analysis showed a ca. 20-30% increase in storage modulus with the addition of cellulose materials. Tensile strength was not significantly increased with the addition of 10 wt % cellulose, but the elastic modulus increased 38% in virgin polypropylene. The analysis of fracture surfaces revealed that failure initiates at the interface, suggesting that the interfacial strength is weaker than the filler strength.
Project description:In this study, drug-cyclodextrin (CD) complexes were prepared using hot liquid extrusion (HLE) process with an aim to improve solubility and bioavailability of carbamazepine. Saturation solubility studies of CBZ in water and different pH media showed a pH-independent solubility. Phase solubility studies of CBZ at different molar concentrations of beta-cyclodextrin (β-CD) and hydroxypropyl beta-cyclodextrin (HP-β-CD) indicated AL-type solubility profile with stability constants of 574 M-1 and 899 M-1 for β-CD and HP-β-CD. Drug-β-CD and drug-HP-β-CD complexes were prepared using HLE process and conventional methods (such as physical mixture, kneading method, and solvent evaporation) as well. Optimized complexes prepared using HLE viz. CBP-4 and CHP-2 showed a solubility of 4.27 ± 0.09 mg/mL and 6.39 ± 0.09 mg/mL as compared to plain CBZ (0.140 ± 0.007 mg/mL). Formation of drug-CD inclusion complexes was confirmed using DSC, FTIR, and XRD studies. Drug release studies indicated highest release of CBZ from CHP-2 (98.69 ± 2.96%) compared to CBP-4 (82.64 ± 2.45%) and plain drug (13.47 ± 0.54%). Complexes prepared using kneading showed significantly lesser drug release (KMB 75.52 ± 2.68% and KMH 85.59 ± 2.80%) as that of CHP-2 and CBP-4. Pre-clinical pharmacokinetic studies in Wistar rats indicated a significant increase in Cmax, Tmax, AUC, and mean residence time for CHP-2 compared to KMH and plain CBZ. All these results suggest that HLE is an effective method to increase the solubility of poorly water-soluble drugs. Graphical Abstract.
Project description:BackgroundRecent efforts in fungal biotechnology aim to develop new concepts and technologies that convert renewable plant biomass into innovative biomaterials. Hereby, plant substrates become metabolized by filamentous fungi to transform them into new fungal-based materials. Current research is thus focused on both understanding and optimizing the biology and genetics underlying filamentous fungal growth and on the development of new technologies to produce customized fungal-based materials.ResultsThis manuscript reports the production of stable pastes, composed of Fomes fomentarius mycelium, alginate and water with 71 wt.% mycelium in the solid content, for additive manufacturing of fungal-based composite materials. After printing complex shapes, such as hollow stars with up to 39 mm in height, a combination of freeze-drying and calcium-crosslinking processes allowed the printed shapes to remain stable even in the presence of water. The printed objects show low bulk densities of 0.12 ± 0.01 g/cm3 with interconnected macropores.ConclusionsThis work reports for the first time the application of mycelium obtained from the tinder fungus F. fomentarius for an extrusion-based additive manufacturing approach to fabricate customized light-weight 3D objects. The process holds great promise for developing light-weight, stable, and porous fungal-based materials that could replace expanded polystyrene produced from fossil resources.
Project description:The automotive sector is actively pursuing a lightweighting strategy as a means to urgently decrease greenhouse gas emissions, which are a significant driver of climate change. The development of lightweight composite structures has been identified as crucial for enhancing part performance while mitigating negative environmental impacts and adopting energy-efficient manufacturing methods. This comprehensive study aimed to decrease the main reinforcement content of talc in commercial compounds while integrating graphene derived from waste polypropylene (PP) grown on talc and graphene nanoplatelet obtained from waste tires by upcycling processes into the PP compound. The entire value chain of interior automotive part production, from compound development and scaling up with a high-shear mixer, to injection molding of the part and performance tests, was investigated with a focus on sustainability considerations. The successful integration of 4 wt % micron talc, together with 1 wt % graphene nanoparticles and 1 wt % hybrid additive into the blended HomoPP/CopoPP matrix resulted in a 10% weight reduction compared to the conventional part. Moreover, significant improvements in flexural and tensile strength were observed, with enhancements of 52 and 38%, respectively. The uniform dispersion of additives and improved interfacial adhesion between the PP matrix and additives facilitated efficient stress transfer, contributing to enhanced mechanical properties. Furthermore, a systematic life cycle assessment study demonstrated the positive impact of waste PP incorporation on CO2 reduction, achieving a remarkable 95% reduction compared to virgin PP. The developed compound also demonstrated favorable processability and flow properties, supporting its potential for mass production. Overall, this study presents a sustainable and effective approach for lightweight automotive interior part production using a synergistically designed PP compound meeting the requirements of the automotive industry.
Project description:Material extrusion (ME) is a layer-by-layer additive manufacturing process that is now used in personal and commercial production where prototyping and customization are required. However, parts produced from ME frequently exhibit poor mechanical performance relative to those from traditional means; moreover, fundamental knowledge of the factors leading to development of inter-layer strength in this highly non-isothermal process is limited. In this work, we seek to understand the development of inter-layer weld strength from the perspective of polymer interdiffusion under conditions of rapidly changing mobility. Our framework centers around three interrelated components: in situ thermal measurements (via infrared imaging), temperature dependent molecular processes (via rheology), and mechanical testing (via mode III fracture). We develop the concept of an equivalent isothermal weld time and test its relationship to fracture energy. For the printing conditions studied the equivalent isothermal weld time for Tref = 230 °C ranged from 0.1 ms to 100 ms. The results of these analysis provide a basis for optimizing inter-layer strength, the limitations of the ME process, and guide development of new materials.
Project description:Thermal stability determines a material's ability to maintain its performance at desired service temperatures. This is especially important for aluminum (Al) alloys, which are widely used in the commercial sector. Herein, an ultra-strong and heat-resistant Al-Cu composite is fabricated with a structure of nano-AlN and submicron-Al2 O3 particles uniformly distributed in the matrix. At 350 °C, the (8.2AlN+1Al2 O3 )p /Al-0.9Cu composite achieves a high strength of 187 MPa along with a 4.6% ductility under tension. The high strength and good ductility benefit from strong pinning effect on dislocation motion and grain boundary sliding by uniform dispersion of nano-AlN particles, in conjunction with the precipitation of Guinier-Preston (GP) zones, enhancing strain hardening capacity during plastic deformation. This work can expand the selection of Al-Cu composites for potential applications at service temperatures as high as ≈350 °C.
Project description:The development of a multimaterial extrusion bioprinting platform is reported. This platform is capable of depositing multiple coded bioinks in a continuous manner with fast and smooth switching among different reservoirs for rapid fabrication of complex constructs, through digitally controlled extrusion of bioinks from a single printhead consisting of bundled capillaries synergized with programmed movement of the motorized stage.
Project description:Conventional cyclodextrin complexation enhances the solubility of poorly soluble drugs but is solvent-intensive and environmentally unfavorable. This study evaluated solvent-free hot-melt extrusion (HME) for forming cyclodextrin inclusion complexes to improve the solubility and dissolution of ibuprofen (IBU). Molecular docking confirmed IBU's hosting in Hydroxypropyl-β-cyclodextrin (HPβ-CD), while phase solubility revealed its complex stoichiometry and stability. In addition, an 11 mm twin-screw co-rotating extruder with PVP VA-64 as an auxiliary substance aided the complex formation and extrusion. Using QbD and the Box-Behnken design, we studied variables (barrel temperature, screw speed, and polymer concentration) and their impact on solubility and dissolution. The high polymer concentration and high screw speeds positively affected the dependent variables. However, higher temperatures had a negative effect. The lowest barrel temperature set near the Tg of the polymer, when combined with high polymer concentrations, resulted in high torques in HME and halted the extrusion process. Therefore, the temperature and polymer concentration should be selected to provide sufficient melt viscosities to aid the complex formation and extrusion process. Studies such as DSC and XRD revealed the amorphous conversion of IBU, while the inclusion complex formation was demonstrated by ATR and NMR studies. The dissolution of ternary inclusion complexes (TIC) produced from HME was found to be ≥85% released within 30 min. This finding implied the high solubility of IBU, according to the US FDA 2018 guidance for highly soluble compounds containing immediate-release solid oral dosage forms. Overall, the studies revealed the effect of various process parameters on the formation of CD inclusion complexes via HME.