Substantial Enhancement In Mechanical Properties Research Articles

Enhancing Mechanical and Antimicrobial Properties of Dialdehyde Cellulose-Silver Nanoparticle Composites through Ammoniated Nanocellulose Modification.

Given the widespread prevalence of viruses, there is an escalating demand for antimicrobial composites. Although the composite of dialdehyde cellulose and silver nanoparticles (DAC@Ag1) exhibits excellent antibacterial properties, its weak mechanical characteristics hinder its practical applicability. To address this limitation, cellulose nanofibers (CNFs) were initially ammoniated to yield N-CNF, which was subsequently incorporated into DAC@Ag1 as an enhancer, forming DAC@Ag1/N-CNF. We systematically investigated the optimal amount of N-CNF and characterized the DAC@Ag1/N-CNF using FT-IR, XPS, and XRD analyses to evaluate its additional properties. Notably, the optimal mass ratio of N-CNF to DAC@Ag1 was found to be 5:5, resulting in a substantial enhancement in mechanical properties, with a 139.8% increase in tensile elongation and a 33.1% increase in strength, reaching 10% and 125.24 MPa, respectively, compared to DAC@Ag1 alone. Furthermore, the inhibition zones against Escherichia coli and Staphylococcus aureus were significantly expanded to 7.9 mm and 15.9 mm, respectively, surpassing those of DAC@Ag1 alone by 154.8% and 467.9%, indicating remarkable improvements in antimicrobial efficacy. Mechanism analysis highlighted synergistic effects from chemical covalent bonding and hydrogen bonding in the DAC@Ag1/N-CNF, enhancing the mechanical and antimicrobial properties significantly. The addition of N-CNF markedly augmented the properties of the composite film, thereby facilitating its broader application in the antimicrobial field.

Engineering fine grains, dislocations and precipitates for enhancing the strength of TiB2-modified CoCrFeMnNi high-entropy alloy using laser powder bed fusion

TiB2 nano-particle reinforced CoCrFeMnNi composite has been additively manufactured by using laser powder bed fusion (LPBF) technique. In comparison with the matrix CoCrFeMnNi sample, the average grain size of the TiB2 doped CoCrFeMnNi (CoCrFeMnNi + TiB2) sample reduces from 26.27 μm to 7.51 μm, appearing a morphological transformation from columnar grains to fine equiaxed grains and fine dendritic grains. Correspondingly, the compressive yield strength (σy) sharply increases from 484.41 ± 57.81 MPa of CoCrFeMnNi HEA to 952.62 ± 38.15 MPa of CoCrFeMnNi + TiB2, and the tensile yield strength increases from 480.27 ± 1.25 MPa to 834.21 ± 15.93 MPa, revealing a substantial enhancement of mechanical properties. The structural analysis unveils that the CoCrFeMnNi + TiB2 sample formed a tetragonal σ phase beside the FCC matrix and TiB2 phases compared with the single FCC phase of CoCrFeMnNi HEA. Especially, atomic resolution scanning transmission electron microscopy discloses that the TiB2 nanoparticles epitaxially grow onto the FCC matrix phase with [01–10]TiB2//[011]FCC orientation relationship. Theoretical calculations indicate that the enhancement mechanism of the CoCrFeMnNi + TiB2 sample should originate from a synergistic strengthening effect which is induced by grain refinement, TiB2 particles, σ phases and dislocations. Our work should provide a new view to utilize the rapid solidification process of LPBF and ceramic nano-particle reinforcement for the enhanced mechanical properties of HEAs with great potential.

Microstructural changes and formability of Al–Mg ultrafine-grained aluminum plates processed by multi-turn ECAP and upsetting

The article focuses on an evaluation of the microstructure, mechanical properties, anisotropy and formability of ultrafine-grained plates of commercial aluminium alloy 5754, with a main addition of Mg. For manufacturing plates, a hybrid Severe Plastic Deformation process is proposed that combines multi-turn Equal Channel Angular Pressing with upsetting, a conventional metal forming process. It was possible to acquire plates of an average grain size of around 0.4 μm and a fraction of high-angle grain boundaries reaching an average of 70%. Due to the high accumulated strain during the processing, it was possible to achieve a Yield Strength and Ultimate Tensile Strength equal to 430 and 450 MPa, respectively, which is a 200 and 120% increase over the initial condition. The anisotropy of the mechanical properties in plate's plane was negligible. The Lankford parameter was used to evaluate formability, and its values proved to be similar to those acquired from other processing techniques. This combination of a substantial enhancement of mechanical properties and typical anisotropy parameters values offers an attractive technology for the production of high-strength plates suitable for further metal forming.

Tough Materials Through Ionic Interactions.

This article introduces butyl acrylate-based materials that are toughened with dynamic crosslinkers. These dynamic crosslinkers are salts where both the anion and cation polymerize. The ion pairs between the polymerized anions and cations form dynamic crosslinks that break and reform under deformation. Chemical crosslinker was used to bring shape stability. The extent of dynamic and chemical crosslinking was related to the mechanical and thermal properties of the materials. Furthermore, the dependence of the material properties on different dynamic crosslinkers—tributyl-(4-vinylbenzyl)ammonium sulfopropyl acrylate (C4ASA) and trihexyl-(4-vinylbenzyl)ammonium sulfopropyl acrylate (C6ASA)—was studied. The materials’ mechanical and thermal properties were characterized by means of tensile tests, dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric analysis. The dynamic crosslinks strengthened the materials considerably. Chemical crosslinks decreased the elasticity of the materials but did not significantly affect their strength. Comparison of the two ionic crosslinkers revealed that changing the crosslinker from C4ASA to C6ASA results in more elastic, but slightly weaker materials. In conclusion, dynamic crosslinks provide substantial enhancement of mechanical properties of the materials. This is a unique approach that is utilizable for a wide variety of polymer materials.

Effect of Graphene Oxide Nanoparticles on the Physical and Mechanical Properties of Medium Density Fiberboard.

In this research, the special effects of graphene oxide nanoparticle charging (0, 2, 4, 6, wt.%) on the properties of medium-density fiberboard were examined. Physical and mechanical properties of the panels were determined conferring the method of European Norm standards. The consequences exhibited substantial enhancement in mechanical properties, explicitly in modulus of rupture, modulus of elasticity and internal bonding for 2–6% nanoparticle addition in a urea–formaldehyde resin. The mechanical properties, i.e., internal bond, modulus of elasticity and modulus of rupture were improved by 28.5%, 19.22% and 38.8%, respectively. Results also show a clear enhancement in thickness swelling and water absorption. The physical properties of thickness swelling, water absorption and thermal conductivity were improved up to 50%, 19.5% and 39.79%, respectively. The addition of graphene oxide nanoparticles strongly affected the curing time of the urea–formaldehyde resin and improved its thermal stability.

Mechanical behaviour of 3D printed Lightweight Nano-composites

Background: The nanoclay (NC) and glass micro balloons (GMB) based reinforced polymer composites are explored extensively through traditional processing methods. NC shows substantial enhancement in mechanical properties. Polymer composites developed by reinforcing GMB fillers provide a substantial reduction in weight, which is essential in the marine, aerospace, and automotive field. In this study, an attempt is made by developing polymer nano composites by reinforcing NC and GMB particles. Objective: The paper deals with 3 dimensional printing (3DP) of lightweight nanocomposite foam (NF) developed by mixing nanoclay (NC) and glass micro balloons (GMB) in high-density polyethylene (HDPE). The NF blend is prepared by keeping NC at 5 weight %. Subsequently, GMBs are added by volume (20 - 60 %) to NC/HDPE blend to realize lightweight NFs. Methods: The lightweight feedstock filaments are developed by extruding the blends using a single screw extruder. The extruded NF filaments are used as an input in a 3D printer to print NFs. The density of extruded filaments and prints are measured. The printed NFs are subjected to tensile and flexural testing. Conclusion: With an increase in GMB loading the density of both filaments and prints decreases. Compared to neat HDPE, printed NFs show ~30 % weight reducing potential. The tensile, flexural modulus and strength increases with GMB loading. NFs exhibited superior mechanical performance as compared to HDPE and NC/HDPE. Further, the property map reveals that the 3D printed NFs show superior tensile, flexural modulus, and strength in comparison with injection and compression-molded foams.

Substantial enhancement of mechanical properties for SnSe based composites with potassium titanate whiskers

Highly dense p-type polycrystalline SnSe dispersed with x vol% K2Ti6O13 whiskers (x = 0, 1, 3, 5) were fabricated by a high-pressure sintering (HPS) method. The effects of the K2Ti6O13 whiskers additives on the thermoelectric as well as mechanical properties of the composites were characterized in detail. The electrical conductivity, Seebeck coefficient, and thermal conductivity were measured within the temperature range of 300–830 K. It was found that the K2Ti6O13 whiskers were distributed homogeneously throughout the matrix and contacted with the SnSe grains intimately. Mechanical properties, such as Vickers hardness, flexural strength, compressive strength and fracture toughness of the composites were improved significantly. Especially, upon the addition of 5 vol% K2Ti6O13 whiskers, the flexural strength and compressive strength were almost doubled as compared to K2Ti6O13-free samples. Such substantial enhancement of mechanical properties is an important benefit for the commercial application of thermoelectric devices.

Tailoring mechanical and antibacterial properties of chitosan/gelatin nanofiber membranes with Fe3O4 nanoparticles for potential wound dressing application

In this work, magnetic Fe3O4 nanoparticles (NPs) were utilized to improve the mechanical and antibacterial properties of chitosan (CS)/gelatin (GE) composite nanofiber membranes. Homogeneous Fe3O4/CS/GE nanofibers were electrospun successfully. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirmed the presence of well-dispersed Fe3O4 NPs in the composite nanofibers. Fourier transform infrared spectroscopy (FTIR) spectra revealed the effective interactions of Fe3O4 NPs to the composite matrix through hydrogen bonding. The improvement on the thermal stability of the Fe3O4/CS/GE was observed by differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA), which is tightly correlated to strong filler-matrix adhesion. The incorporation of Fe3O4 NPs resulted in a substantial enhancement of mechanical properties. The optimum mechanical performance was demonstrated on 1wt% Fe3O4/CS/GE nanofiber membranes, achieving 155% augment of Young's modulus, 128% increase of tensile strength, and 100% boost of toughness from CS/GE. The excellent mechanical enhancement can be explained by the effective dispersion of fillers and the filler-matrix interactions, which ensures the efficient load transfer from CS/GE matrix to Fe3O4 nanofillers. Moreover, zones of inhibition for Escherichia coli and Staphylococcus aureus expanded markedly with the supplement of Fe3O4 NPs. In all, nanofiber membranes made of Fe3O4/CS/GE composite with tailored mechanical and antibacterial properties appear a promising wound dressing material.

High density polyethylene and silane treated silicon nitride nanocomposites using high-density polyethylene functionalized with maleate ester: Mechanical, tribological and thermal properties

In this study, attempt has been made to improve the overall performance of high-density polyethylene (HDPE) composites by blending with silane treated silicon nitride (SN) using HDPE grafted dibutyl maleate as compatibilizer. A small quantity of surface modified nanoclay has also been added in order to improve the mechanical properties. The mechanical properties show that both silane modification of silicon nitride accompanied by nanoclay addition has led to the substantial enhancement in mechanical properties. In addition, compatibilization has further improved the mechanical properties showing 10% (w/w of silicon nitride) as optimal compatibilizer content. The wear results showed that, as SN content increased, the slide wear loss decreased. Addition of SN along with compatibilizer also improved the thermal stability of the nanocomposites.

LBL Assembled Laminates with Hierarchical Organization from Nano- to Microscale: High-Toughness Nanomaterials and Deformation Imaging

Layer-by-layer assembly (LBL) can generate unique materials with high degrees of nanoscale organization and excellent mechanical, electrical, and optical properties. The typical nanometer scale thicknesses restrict their utility to thin films and coatings. Preparation of macroscale nanocomposites will indicate a paradigm change in the practice of LBL, materials manufacturing, and multiscale organization of nanocomponents. Such materials were made in this study via consolidation of individual LBL sheets from polyurethane. Substantial enhancement of mechanical properties after consolidation was observed. The resulting laminates are homogeneous, transparent, and highly ductile and display nearly 3x higher strength and toughness than their components. Hierarchically organized composites combining structural features from 1 to 1 000 000 nm at six different levels of dimensionality with a high degree of structural control at every level can be obtained. The functionality of the resulting fluorescent sandwiches of different colors makes possible mechanical deformation imaging with submicrometer resolution in real time and 3D capabilities.

The structure and property of the electrospinning silk fibroin/gelatin blend nanofibers

AbstractNanofibers could provide benefits due to high surface area for biomaterial scaffolds. In order to improve both silk fibroin and gelatin performance for potential biomedical applications, in this article the electrospinning of silk fibroin (SF)/gelatin (GT) blends with different composition ratio and concentration was performed with formic acid as a spinning solvent. The nanofibers morphologies and diameters were observed by Scanning electron microscopy (SEM). Blending with GT could improve the viscosity and spinnability of spinning solution. As-spun SF/GT blend nanofibers were more homogeneous and non-beaded than pure SF nanofibers. The diameter decreased with higher voltage at same electric field intensity. On increasing the concentrations of spinning solution, the pore diameter of nanofibers decreased, and the porosity increased. In addition, FTIR and DTA analyses showed SF/GT nanofibers had more β-sheets than pure SF nanofibers, which may be caused by an intermolecular interaction between SF and GT. Blending with GT also led to substantial enhancement in mechanical properties of SF nanofibers.

Crosslinking of the electrospun gelatin nanofibers

Gelatin (Gt) nanofibers have been prepared by using an electrospinning process in a previous study. In order to improve their water-resistant ability and thermomechnical performance for potential biomedical applications, in this article, the electrospun gelatin nanofibers were crosslinked with saturated glutaraldehyde (GTA) vapor at room temperature. An exposure of this nanofibrous material in the GTA vapor for 3 days generated a crosslinking extent sufficient to preserve the fibrous morphology tested by soaking in 37 °C warm water. On the other hand, the crosslinking also led to improved thermostability and substantial enhancement in mechanical properties. The denaturation temperature corresponding to the helix to coil transition of the air-dried samples increased by about 11 °C and the tensile strength and modulus were nearly 10 times higher than those of the as-electrospun gelatin fibers. Furthermore, cytotoxicity was evaluated based on a cell proliferation study by culturing human dermal fibroblasts (HDFs) on the crosslinked gelatin fibrous scaffolds for 1, 3, 5 and 7 days. It was found cell expansion took place and almost linearly increased during the course of whole period of the cell culture. The initial inhibition of cell expansion on the crosslinked gelatin fibrous substrate suggested some cytotoxic effect of the residual GTA on the cells.

Textures and mechanical behavior of Mg–3.3%Li alloy after ECAP

The texture evolutions of the Mg–3.3%Li alloy after the equal channel angular pressing (ECAP) with two different routes have been investigated by neutron diffraction . The substantial enhancement of mechanical properties of the alloy after ECAP has been explained by the texture modifications and microstructure changes.

Microstructure and abrasive wear of cobalt-based laser coatings

Cobalt-based alloys are used as wear-resistant materials for hardfacing cheap steel substrates. A substantial enhancement in mechanical properties of cobalt-based superalloys is attributed to the martensitic fcc {yields} hcp phase transformation. Alloying elements can be classified as phase modifiers (Ni and Fe stabilize fcc whereas W and Cr stabilize hcp), solid-solution strengtheners (W and Mo), which affect only the matrix, and elements that form carbides (Cr-rich M{sub 7}C{sub 3} and M{sub 23}C{sub 6}, M = metal). Of the different depositing techniques such as plasma spray, tungsten inert gas, oxyacetylene flame and laser cladding, the latter delivers coatings with a low dilution with the substrate material and no pores. Moreover, the laser cladding process has the advantage of being well controllable. This paper reports on the deposition of five different cobalt-based Stellite alloys on steel substrates by laser cladding.