High Mechanical Properties Research Articles

Bio-derived epoxy thermosets incorporating imine linkages: Towards sustainable and advanced polymer materials

In the search for sustainable and eco-friendly alternatives, Schiff-based epoxy thermosets are emerging as a promising strategy due to the inherent dynamic and reversible nature of their imine functional groups, which enables thermal reprocessability and chemical recyclability. This article explores the synthesis of Schiff-based epoxy thermosets using sustainable approaches. Starting from vanillin or syringaldehyde, the synthesis involves the incorporation of imine linkages into the epoxy network. A new strategy has been employed by self-polymerization without the use of additional curing agents. This approach conducts to novel thermosets with superior material properties that exceed those reported in previous studies. Thermo-mechanical investigations showed that the designed thermosets have high mechanical properties, with storage moduli at room temperature ranging between 1.5–2.2 GPa, and glass transition values between 138 and 249 °C. Thermal analyses allowed to evaluate the Limit Oxygen Index (LOI) which ranged from 33 % to 36 %, demonstrating excellent flame-retardant properties without the addition of supplementary additives. Their reduced density (0.74–1.09 g/cm3) makes them suitable for applications where weight considerations are critical. These results obtained results place the designed Schiff-based materials as promising candidates for a wide range of high-end applications, particularly in industries that prioritize eco-friendly processes and materials.

High thermal and mechanical properties of carbon fiber network reinforced copper matrix composites achieved by configuration design and interface engineering

Constructing three-dimensional (3D) fillers within the matrix represents a highly promising strategy for achieving excellent comprehensive performance. In this study, the possibility of implementing 3D network configuration in carbon fiber/copper (CF/Cu) composites is explored. A novel composite structure was developed through template-electrodeposition and hot-pressing sintering techniques, incorporating a 3D CF network within the Cu matrix. Additionally, tungsten carbide (WC) coating was applied to the CF surface using molten salt method. Research findings indicate that the 3D CF networks establish continuous heat flow channels within the Cu matrix, while the WC coating mitigates the interfacial thermal resistance by improving CF-Cu interface bonding. The 3D-CF(WC)/Cu composite obtained through the synergistic strengthening of configuration design and interface engineering exhibits excellent thermal and mechanical properties. The thermal conductivity (TC), coefficient of thermal expansion (CTE), and bending strength of the 3D-CF(WC)/Cu composite in the in-plane direction are 457.4 ± 9.0 W m−1 K−1, 6.9 ± 0.4 × 10−6 K−1, and 281.9 ± 5.2 MPa, respectively; and in the through-plane direction are 400.8 ± 8.9 W m−1 K−1, 6.1 ± 0.4 × 10−6 K−1, and 263.1 ± 5.6 MPa, respectively. This research provides a novel approach to develop carbon reinforced metal matrix thermal management composites.

EVOLUTION OF THE PRESS BONDING PROPERTIES OF Al/Cu BIMETAL BULK COMPOSITES (EXPERIMENTAL AND NUMERICAL INVESTIGATION)

Nowadays, the application of bimetallic laminates with special capabilities is increasing and has experienced high growth. These properties include high corrosion resistance, mechanical properties, thermal stability, and lightweight. In the midst of the technologies of multilayer composite materials, accumulative press bonding (APB) as a solid-phased method of welding is one of the most common techniques for the production of multilayer composites. One of the most important aims for this choice is the press pressure, which can generate a suitable mechanical connection and strong bonding between produced metal layer components. In this study, bimetal aluminum/copper bulk composites have been fabricated via the APB technique. Then, the effect of pressing parameters such as plastic strain and the number of layers on the stress distribution has been investigated. For samples with eight layers, the shear stress between the layers reached 3.1 MPa which is a suitable condition to generate a successful bonding. The stress applied on the layers has also increased with increasing the thickness reduction ratio. The interlayer shear stresses also increase with decreeing the thickness. With a higher reduction in thickness ratios, the amount of sinking layers was greater along the entire length of the sample, which led to the crushing of copper layers. During the APB process at higher pressing passes, increasing the volume of virgin material in the direction of the press led to increasing the compaction and better bonding of Al and Cu layers to each other.

The evaluation of the aging process in 15-5 PH materials in terms of formability and microstructure

In this study, the effects of aging heat treatment of 15-5 PH stainless steel material on the mechanical properties, microstructure, and formability were investigated. Instead of cooling in air, cooling in the oven spontaneously was applied in the oven for the first time. Experimental studies show that aging heat treatment was applied for H900, H1025, and H1150 conditions at temperatures of 482 °C, 552 °C, and 621 °C, respectively, and 60 min for H900 and 240 min for H1025 and H1150. It has been observed that controlled cooling in the oven increases the mechanical values of the material obtained by cooling in the air by 8%–10%. The microstructures of the conditions after heat treatment were also examined, and it was observed that the cooling aging heat treatment in the oven caused precipitation hardening in the microstructure of the material. In addition, when evaluating the formability of the results using V-bending, it was observed that materials which could not withstand bending beyond 75° in Condition A (Con A), the initial state of the material, were smoothly shaped in all conditions and at all angles as a result of the cooling process in the oven. A decrease in spring-back angles has been detected due to the decrease in mechanical properties caused by increasing aging temperature. The highest spring-back value was also observed on a 75° bending die with 10.948° in the H900 condition which has the highest mechanical properties.

Microstructure and mechanical properties of 3D‐printed zirconia bone scaffold: Experimental and computational analysis

AbstractMicroextrusion‐based additive manufacturing of zirconia‐based bioceramics is capable of fabricating design‐specific architectures with high mechanical strength properties and relative density. We developed a novel organic residue‐free binder system for zirconia paste printing (ZP2) with the shear‐thinning properties apropos to microextrusion‐based 3D printing. Based on thermogravimetric analysis, debinding protocol was established followed by high‐temperature heat treatment under four sintering conditions. Quantitative linear shrinkage (32.3%–42.7% ranging from in‐plane to vertical direction), density (83.3%–87.5%), and surface roughness (7.7–13.8 µm from the parallel to the perpendicular to the infill direction) as a factor of sintering conditions (1400°C–1500°C for 3–4 h) were analyzed. Whereas qualitative phase assemblage demonstrated “sintering condition independent” phase stability; grain growth and reduction in porosity were observed in the microstructure with increment in sintering temperature and hold time. Interestingly, at higher temperature and hold time, the compressive (46–72.4 MPa) and tensile strength (16.2–23.1 MPa) properties experienced a trade‐off between grain growth and reduction in porosity. The ZP2 scaffolds sintered at lower temperature and hold time qualified for the bone scaffold applications having interconnected porosities, biologically relevant surface roughness, and human bone mimicking mechanical properties. With a unique finite element analysis recipe, the mechanical behavior of the “life‐like” reconstructed computer aided design (CAD) geometries identical to real 3D‐printed‐sintered ZP2 scaffolds was quantitatively predicted.

A highly stretchable and self-adhesive cellulose complex hydrogels based on PDA@Fe3+ mediated redox reaction for strain sensor

As the application of conductive hydrogels in the field of wearable smart devices is gradually deepening, a variety of hydrogel sensors with high mechanical properties, strong adhesion, fast self-healing, and excellent conductivity are emerging. However, it is still a great challenge to manufacture hydrogel sensors combining multiple properties. Herein, we leveraged the dynamic redox reaction occurring between polydopamine (PDA) and Fe3+ to induce ammonium persulfate (APS) to generate free radicals, thereby initiating the copolymerization of hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) monomers. Then, polypyrrole-encapsulated cellulose nanofibers (PPy@CNF) and carboxymethylcellulose (CMC) were incorporated as conductive reinforced nanofillers and interpenetrating network skeleton. The obtained hydrogel cross-linked through reversible metal-ligand bonds, π-π stacking and abundant hydrogen bonding demonstrated great mechanical properties (strength 240.4 kPa, strain 1175 %) and self-healing ability (88.96 %). Particularly, the gel displayed ultrahigh durability and skin adhesive ability (75 kPa after 10 cycles), surpassing previous skin adhesion hydrogels. Furthermore, through the synergistic conductive effect of PPy@CNF and Fe3+, the prepared hydrogel sensor possessed high sensitivity (GF = 1.89) with a wide sensing range (~1000 %), which could realize the human body's daily motion detection, and had a promising application in flexible wearable electronics.

Carbon fiber/nano SiO2 reinforced polyelectrolyte-graft UHMWPE for water lubricated superlubricity

In this study, a new kind of UHMWPE composite with ultralow coefficient of friction (COF) and high mechanical properties was developed. An efficient method was established to graft hydrophilic monomer 3-sulfopropyl methacrylate potassium salt (SPMK) onto UHMWPE powder by thermal initiation radical polymerization. The COF of UHMWPE grafted SPMK sample was significantly reduced by 50 %. After filling carbon fiber and nano SiO2, the COF of UHMWPE composites can be reduced as low as 0.009 at 0.1 m/s. Besides, a 76.1 % decrease in wear rate of single UHMWPE was achieved. The outstanding tribological properties of UHMWPE composite was attributed to the synergistic effect of hydration lubrication and particle reinforcement. The prepared UHMWPE composite has great potential to realize water lubricated bearing.

Mechanical Force on Hydrogel Implication on Enhanced Drug Release, Antibacterial, and M2 Macrophage Polarization: New Insights Alleviate Diabetic Wound Healing.

Diabetic foot ulcers/chronic wounds are difficult to treat because of dysfunctional macrophage response and decreased phenotype transition from the M1 to M2 status. This causes severe inflammation, less angiogenesis, microbial infections, and small deformation in wound beds, affecting the healing process. The commercial wound dressing material has limited efficacy, poor mechanical strength, extra pain, and new granulated tissue formed in a mesh of gauze. It is desired to create tough, skin-adhesive, antifouling, sustainable M2 phenotype-enabling, and mechanoresponsive drug-releasing hydrogel. To resolve this, zwitterionic poly(sulfobetaine methacrylate) (SB) incorporated with keratin-exfoliated MoS2 and bee-wax nanoparticles were developed to deliver phenytoin upon application of mechanical forces. Human hair keratin was used for exfoliation of MoS2, and bee-wax nanoparticles loaded with phenytoin were used as cross-linkers of SB hydrogel. The cross-linked SB-MO15-B hydrogel has high mechanical properties, with more tensile strength and strain of 118 kPa and 1485%. Under external mechanical force, hydrogel deformed to release phenytoin of 38% (tensile) and 24% (compressive), which was higher compared to static condition (12%). The penetration of phenytoin into skin tissue was also improved by the mechanical force applied to the hydrogel. SB-MO15-B hydrogel effectively activates the polarization of macrophages toward the M2 phenotype, promotes cell proliferation, and also shows superior antibacterial properties. In vivo results demonstrate that hydrogel rapidly promotes diabetic wound repair through fast antiinflammation and M2 macrophage polarization. Therefore, a robust mechanoresponsive hydrogel would provide a new strategy to deliver the drug and also tune the M2 macrophage polarization for chronic wound healing.

Enhancing the performance of recyclable polyurea through coordination of rigid chain segments and graphene platelets

In response to the global focus on environmental preservation and sustainable practices, developing nanocomposites featuring recyclable and healing properties is indispensable for high-performance and long-life structures. This study presents a facile approach to develop a recyclable and thermally-induced healing polyurea (PU)/graphene platelet (GNP) nanocomposites with high mechanical properties. A straightforward synthesis method was employed using isophorone diamine (IPDA) as chain extender with rigid cyclic structure. GNPs were modified with IPDA before adding into PU, showing remarkable enhancements in mechanical performance. At 0.10 wt.% GNPs, PU nanocomposites exhibited the maximum mechanical properties, with modified GNPs (M-GNPs) significantly outperforming pristine GNPs. Specifically, the tensile strength of PU increased by 41.3 % with M-GNPs, compared to only 12 % with pristine GNPs, underscoring the critical role of modifying the reinforcing phase. Furthermore, the nanocomposites demonstrated outstanding healing capabilities, achieving 89 % healing efficiency after 24 h at 120 °C. In addition, PU/M-GNP nanocomposites showed exceptional resistance to acidic and alkaline environments in comparison to neat PU. The study not only exemplifies developing high-strength and environmentally friendly materials but also holds promise for diverse applications, including aerospace, vibration damping, and protective coatings.

Dense nine elemental high entropy diboride ceramics with unique high temperature mechanical and physical properties

Due to their huge composition space and superior performance characteristics, high entropy borides have garnered great interest in many fields, particularly where their high-temperature performances at high temperatures are critical. Herein, we first discovered that dense (Ti1/9Zr1/9Hf1/9Nb1/9Ta1/9V1/9Cr1/9Mo1/9W1/9)B2 (HEB9) ceramics prepared at 1850 °C showed an exceptionally low temperature coefficient of electrical resistivity (4.28 × 10−4 K−1), which is ∼38% of that of (Ti1/5Zr1/5Hf1/5Nb1/5Ta1/5)B2 (HEB5) and nearly an order of magnitude lower than those of previously reported ZrB2 and ZrB2-30 vol% SiC ceramics. Their mechanical, thermophysical properties at elevated temperatures were also investigated systematically. Although the thermal conductivity of HEB9 increased with elevated temperatures, it remained at a very low level (∼29 W/(m·K)) at 1273 K, nearly half that of HEB5. Interestingly, it is found that the thermal conduction of HEB9 and HEB5 was mainly contributed by electrons, suggeting their thermal conductivity could be roughly estimated from corresponding electrical conductivity values. Moreover, HEB9 exhibited a geometrically necessary dislocation density over 30 times greater than HEB5, likely contributing to its higher Vickers hardness and unique physical properties. Notably, the flexural strength of HEB9 at 1600 °C was even improved to 650.0 ± 86.3 MPa, compared to the value (559.7 ± 36.7 MPa) at room temperature without degradation, which was comparable to that of HEB5, although thermodynamic calculations indicated a lower melting point of HEB9 and grain boundary softening was occurred in HEB9 at higher temperatures. The excellent mechanical, electrical and thermophysical properties of HEB9 at elevated temperatures make it a competitive candidate for various high-temperature applications.

Nanotechnology-enhanced castability of wrought aluminum alloys 2024 and 6063

In the realm of high-performance applications, wrought aluminum alloys are esteemed for their high mechanical properties and excellent strength-to-weight ratio. However, their limited castability poses challenges in economically producing intricate structures through casting processes. To address this issue, a small proportion of TiC nanoparticles is introduced into the melts of AA 2024 and AA 6063 for nano-treating. This nano-treatment imparts several beneficial effects, including the delayed release of latent heat, inhibition of grain growth, and improvement of wettability. These effects enhance the fluidity of the melt, eliminate hot cracking, and elevate the surface quality of the castings. The outcomes underscore the promising potential of emerging nano-treatment technology in rendering traditionally non-castable wrought aluminum alloys suitable for cost-effective casting processes, ultimately delivering high-performance products for a wide range of applications.

High Mechanical Property, Hydrophobic and Fire-Retardant Cellulose Film Derived from Kenaf Degumming Wastewater

High Mechanical Property, Hydrophobic and Fire-Retardant Cellulose Film Derived from Kenaf Degumming Wastewater

Refinement of eutectic structure and precipitates of Cu–20Ag alloy due to Y microalloying

Copper-silver alloy rod with high mechanical properties and stable conductivity are the key materials for the preparation of microfilaments used in endoscopy and other medical fields. In this paper, the microstructure of Cu–20Ag rod was regulated by adding trace rare earth Y in order to improve the comprehensive performance of copper-silver alloy further. and studies the distribution and existence of rare earth Y as well as the influence on the performance of copper-silver alloy rod billet. The results of research show that: rare earth Y mainly exists in the branching nodes of the eutectic organization, so that the alloy in the solidification of constitutional supercooling increases, thus refining the eutectic structure, and make it uniformly distributed. After addition of 0.01 wt%Y, Cu4Y was precipitated in the eutectic structure of the rod. After adding 0.03 wt%Y, the precipitates types increased to trace intermetallic compound AgY and nanoparticles Cu4Y. The increase of the interface between eutectic structure and Cu matrix decreases the electron scattering probability. This is the main factor to lead to the decrease of electrical conductivity. The precipitation hardening of precipitated phase and the increase of interface between eutectic structure and Cu matrix are the main factors for the increase of tensile strength of bar billet. The main factor of the decrease in the conductivity of rod billet is the increase of Ag phase dissolved in eutectic structure and the interface between eutectic structure and Cu matrix.

Superhydrophobic and super-stretchable conductive composite hydrogels for human motion monitoring in complex condition

With the advent of the information age, there is a growing demand for wearable sensing devices. Conventional hydrogels are a class of materials that can hold a large amount of water, with a three-dimensional network of hydrophilic polymerization chains inside. In remote areas or harsh environments, there is an urgent demand for a flexible sensor that is environmentally stable, wearable, and has high mechanical properties. Due to the hydrophilicity of the traditional hydrogel surface, it is easy to adsorb dust or be contaminated by liquid, which limits its further application. As a result, the superhydrophobic hydrogel F-PTD was designed using SiO2@PDA, F-HNT and PT hydrogel. TGA, XPS, SEM, FT-IR was used to characterize the structure of F-PTD, respectively. Based on the study of mussels, the adhesion property of polydopamine was utilized as an adhesion agent between organic–inorganic interfaces while improving the roughness of the hydrogel surface. The fabricated F-PTD superhydrophobic conductive hydrogels have excellent stretchability (Tensile Strain > 500 %), stable hydrophobicity (CA > 150°), and sensitive electrical conductivity (GF = 3.49). The contact angle of F-PTD is greater than 150° for tensile strains in the range of 0–350 %, and it maintains superhydrophobic under corrosive solutions with pH = 1–14. This enables F-PTD to perform the sensing function of detecting human body signals under complex environmental conditions, which has great potential for application in the field of underwater rescue, wearable electronics and human–computer interfaces.

Assessment of recycling and repair methods for discontinuous glass fiber reinforced vitrimer composites with reclaimed parts

In the context of fiber-reinforced polymer composites, the pursuit of sustainability is of paramount importance to promote environmentally responsible practices. Vitrimer materials have recently gained significant attention for their potential to enable repair and recycling, rendering them an attractive choice for manufacturing eco-friendly composites while maintaining mechanical strength akin to a thermoset resin like epoxy. This study specifically focuses on glass fibers, and delves into the examination of mechanical properties using both chemical and mechanical recycling methods for quasi-isotropic, randomly dispersed discontinuous glass fiber-reinforced vitrimer composites. It places specific emphasis on the optimization of factors to promote sustainable production. The findings indicate that chemical recycling methods are remarkably effective, resulting in the almost complete restoration of mechanical properties when appropriately selected process parameters are applied. Additionally, this study investigates diverse repair techniques, with the overlap repair method exhibiting the highest degree of recovery. These findings underscore the remarkable potential of glass fiber reinforced vitrimer composites, characterized by their high mechanical properties, for applications in various industries, particularly in structural contexts. Overall, this study highlights the significant reduction in composite waste achievable through recycling and repair strategies, aligning with the broader goal of advancing sustainability within the domain of engineering and manufacturing.

Cross-Linking Agent Based on the Dynamic Bond and Resultant Epoxy Adhesive with a High Mechanical Property

Cross-Linking Agent Based on the Dynamic Bond and Resultant Epoxy Adhesive with a High Mechanical Property

High-efficiency 1.6 μm-band fiber laser based on single Er3+-doped tungsten tellurite glass with high mechanical strength through tailored glass network

In this study, the correlation between the Raman structure, thermal stability, and mechanical properties of TeO2-ZnO-La2O3–WO3 glasses with varying WO3 contents are systematically established. By exploring the critical point in the transformation process of glass network structural units, the optimal glass components of 74TeO2-12ZnO-5La2O3–9WO3 glass possess the maximum thermal stability (158 °C) and the highest mechanical properties at the same time. The maximum Vicker hardness and Young's modulus of the optimal glass can reach up to 4.007 GPa and 56.212 GPa, which are higher than those of the well-known TeO2-ZnO-Na2O (TZN) and TeO2-ZnO-La2O3 (TZL) glasses. Furthermore, the 0.5 mol% Er3+-doped glass at this critical point (TZLW-0.5Er) exhibits a higher laser figure of merit (54.29 × 10−21 cm2 ms), a larger laser gain bandwidth value (116 nm) and higher emission cross-sections at 1600 nm (2.52 × 10−21 cm2) and 1625 nm (1.06 × 10−21 cm2) than other host glasses. Finally, high-efficiency laser outputs at 1600 and 1625 nm based on TZLW-0.5Er glass fiber are successfully achieved by simulation. These results show the greater practical potential of TZLW-0.5Er glass with higher mechanical strength compared to TZN and TZL fibers for the 1.6 μm-band laser.

Effect of acid-etching 3D printed Ti templates on mechanical properties and corrosion resistance of Mg alloy scaffolds with different pore geometries

Segmental bone defect repair currently remains a major challenge in orthopedic clinics. In this study, to match different implantation positions, different pore geometries (P, G and Do) of Mg alloy scaffolds were designed and prepared by infiltration casting with the acid-etching treated Ti scaffold as the templates. The results showed that the acid-etching treatment for Ti templates resulted in a smoother surface of the Mg alloy scaffolds with improving the mechanical properties and corrosion resistance. Both experiments and simulations showed that the P scaffold had the highest mechanical properties, with yield strength and elastic modulus up to 26.7±2.1 MPa and 327.1±16.2 MPa, respectively. And the P scaffold had the best corrosion resistance after cleaning the Ti template, with a degradation rate of 0.34±0.17 mm/y at 228 h. In vitro cellular experiments showed good cytocompatibility on the surface of all three scaffolds.

Response surface methodology and process optimization of spark plasma sintered parameters of Ti20Al20Cr5Nb5Ni19Cu12Co19 high entropy alloy

Study was carried out on the effect of milling and sintering process parameters on the relative density and microhardness property of a septenary non-equiatomic Ti20Al20Cr5Nb5Ni19Cu12Co19 high entropy alloy fabricated via spark plasma sintering (SPS) process at 100 °C/min constant heating rate, 5 min dwell time, and at a pressure of 50 MPa. A predictive model was developed through response surface methodology (RSM) using the SPS sintering temperature (ST) and milling time (MT) as the process variables. In order to reduce the number of experimental runs, the design of experiment (DOE) technique was used, to eventually avoid the trial-and-error process associated with conventional experimental procedures. The user-defined design (UDD) of the RSM was used to forecast the optimal operating parameters, and the outcome was validated by experiments. Findings indicate that MT and ST are important in achieving high densification, which leads to high densification and mechanical properties. Optimization model shows that, at MT of 7.20115 h and ST of 899.742 °C, desirable responses of 99.9 % relative density, percentage porosity of 0.0999994 % and a micro-hardness value of 835.21 HV can be attained.

Wet-adaptive Strain Sensor Based on Hierarchical Core-sheath Yarns for Underwater Motion Monitoring and Energy Harvesting

Bifunctional flexible electronics with motion monitoring and energy harvesting have broad application prospects in day-to-day activities of human society. Nevertheless, conventional electronics are difficult to adapt to the wear comfortability and anti-sensing interference properties in wet environments. Herein, a wet-adaptive spandex/graphene@cotton/polyurethane yarn (SGCPY) sensor is fabricated with excellent sensing and triboelectric performance, which comprises core layer of spandex fibers, middle layer of graphene@cotton sensing fibers and outer layer of spindle-knotted polyurethane nanofibers. Benefiting from its unique structure, as-prepared SGCPY sensor exhibits high mechanical properties (~80%), superhydrophobic performance (>130°), good strain sensitivity (1.82) and fatigue resistance (12000 cycles) even under water condition. The usage of the SGCPY sensor is demonstrated for the stable monitoring of human body motions and human-machine interaction in both air and water environments. When SGCPY sensor weave as plain fabric, the textile also can convert various mechanical energy into electric power for driving electronic device, showing a maximum voltage of ~3.9V and ~0.7V with solid-solid and liquid-solid contact. This work fosters the in-depth study of textile-based electronics for underwater applications and highlights the promising prospects of multi-functional flexible electronics based on textiles.