Tensile Elastic Modulus Research Articles

Investigation of nano-basic oxygen furnace slag and nano-banded iron formation on properties of high-performance geopolymer concrete

Abstract Geopolymers have emerged as promising alternatives to traditional cement-based composites, offering enhanced sustainability and opportunities for recycling industrial waste. The incorporation of waste materials into the binding matrix of geopolymer concrete not only promotes environmental benefits but also significantly improves the overall performance, including mechanical strength, durability, and microstructural integrity of the matrix. This study explores the impact of incorporating varying dosages of nano-basic oxygen furnace slag (NBOFS) and nano-banded iron formation (NBIF) on the properties of high-performance geopolymer concrete (HPGC) that utilizes waste glass as 50% fine aggregate. The research focuses on evaluating both the fresh and mechanical properties, including compressive strength, splitting tensile strength, modulus of elasticity, and flexural strength. Additionally, this study investigated the transport properties of concrete under aggressive environments, such as resistance to chloride penetration, sulfate attack, and sorptivity. The microstructure was examined using scanning electron microscopy. The results demonstrated that the addition of 3% NBOFS and 2.5% NBIF significantly improved the fresh, mechanical, and transport properties of HPGC. These nanomaterials also enhance the splitting tensile strength, flexural strength, and elastic modulus under highly aggressive environmental conditions. The contribution of these nanomaterials to the strength and durability of concrete is particularly relevant in the construction of both substructures and superstructures. Additionally, geopolymer concrete significantly reduces CO2 emissions by eliminating the requirement for ordinary Portland cement and promoting the recycling of waste products, contributing to more environmentally friendly construction practices.

Enhancing mortar performance: A comparative study on particle size of recycled concrete powder and metakaolin in binary and ternary blends

The construction industry generates substantial volumes of construction and demolition waste (CDW), including aggregates and fine particles classified as recycled concrete powder (RCP). This study investigates the sustainable reuse of RCP by evaluating its combined use with metakaolin (MK) as supplementary cementitious materials in both binary and ternary mixtures with Portland cement, aiming to reduce environmental impact without compromising mortar performance. The experimental program assessed two particle sizes of RCP, along with MK, and various replacement levels, which were pivotal parameters in the study. A series of binary and ternary mixtures were prepared with different proportions of RCP and MK, considering replacement levels ranging from 10 % to a maximum of 30 %, using RCP alone or in conjunction with MK. The mortars were analyzed in both fresh and hardened states, focusing on critical properties such as consistency index, compressive strength, splitting tensile strength, elastic modulus, water absorption, density, void index, and capillary water absorption. Furthermore, a microstructural analysis was conducted using scanning electron microscopy (SEM), and a cement consumption efficiency index, along with CO₂ emissions data, was calculated to provide a comprehensive evaluation of performance and sustainability. The findings demonstrate that RCP with a particle size comparable to that of cement (RCP1) significantly enhances both physical and mechanical performance, particularly in ternary mixtures with MK due to its pozzolanic activity, where the silica (SiO₂) and alumina (Al₂O₃) components react to form additional hydrated products, thereby improving the properties of mortars. For instance, the ternary mixture comprising 15 % RCP1 and 15 % MK attained compressive and splitting tensile strength of 29.26 MPa and 3.36 MPa at 28 days, respectively, compared to the reference mixture, which yielded 27.96 MPa and 3.33 MPa. Conversely, larger particle sizes (RCP2) and higher replacement levels led to a decline in performance across all evaluated parameters. Ternary mixtures containing RCP1 also exhibited a higher cement consumption efficiency index and lower CO₂ emissions per MPa. Notably, the mixture with 15 % RCP1 and 15 % MK showed the most favorable indicators overall, with cement consumption and CO₂ emissions measured at 12.08 kg/m³·MPa and 10.01 kgCO₂/m³·MPa, respectively. These results suggest that the synergy between RCP1 and MK enhances particle packing and matrix density, which in turn improves the structural properties of the mortar. The incorporation of MK compensates for the limited reactivity of RCP, especially at higher replacement levels, while the utilization of RCP1 offers significant sustainability benefits by reducing Portland cement consumption. This study demonstrates that the combination of RCP and MK in ternary mixtures presents a technically viable and sustainable alternative for mortar production, optimizing cement use and reducing CO₂ emissions. The innovative application of CDW-derived RCP in construction materials represents a practical approach to promoting more sustainable practices within the industry.

Antibacterial and wound healing stimulant nanofibrous dressing consisting of soluplus and soy protein isolate loaded with mupirocin

Severe cutaneous injuries may not heal spontaneously and may necessitate the use of supplementary therapeutic methods. Electrospun nanofibers possess high porosity and specific surface area, which provide the necessary microenvironment for wound healing. Here in, the nanofibers of Soluplus-soy protein isolate (Sol-SPI) containing mupirocin (Mp) were fabricated via electrospinning for wound treatment. The fabricated nanofibers exhibited water absorption capacities of about 300.83 ± 29.72% and water vapor permeability values of about 821.8 ± 49.12 g/m2 day. The Sol/SPI/Mp nanofibers showed an in vitro degradability of 33.73 ± 3.55% after 5 days. The ultimate tensile strength, elastic modulus, and elongation of the Sol/SPI/Mp nanofibers were measured as 3.61 ± 0.29 MPa, 39.15 ± 5.08 MPa, and 59.11 ± 1.94%, respectively. Additionally, 85.90 ± 6.02% of Mp loaded in the nanofibers was released in 5 days in vitro, and by applying the Mp-loaded nanofibers, 93.06 ± 5.40% and 90.40 ± 5.66% of S. aureus and E. coli bacteria were killed, respectively. Human keratinocyte cells (HaCat) demonstrated notable biocompatibility with the prepared nanofibers. Furthermore, compare to other groups, Sol-SPI-Mp nanofibers caused the fastest re-epithelialization and wound healing in a rat model. The findings of this study present a novel nanofiber-based wound dressing that accelerates the healing of severe skin wounds with the risk of infection.

Achieving high electrothermal and mechanical performance for Graphene/Poly(hexamethylene terephthalamide) composite films via interfacial engineering with two-dimensional polyarylamide nanosheets

Although graphene-based polymer electrothermal films have received great attention, the graphene aggregation restricts the improvement in electrothermal performance. This study reports graphene (GN)/two-dimensional polyarylamide nanosheets (2DPA) filled poly (hexamethylene terephthalamide) (PA6T) composite film with outstanding electrothermal and mechanical performance. Owing to the addition of 2DPA, the as-prepared 2DPA-GN/PA6T composite film can attain a high heating-up rate of 25.5 °C/s, 1.8 times higher than that of GN/PA6T composite film (14.1 °C/s). Furthermore, the 2DPA-modified composite film showed a remarkable heating temperature rise to ∼230 °C, 80 °C higher than that of GN/PA6T composite film (∼150 °C). Additionally, the film had excellent mechanical performance with tensile strength and modulus of elasticity of 32.5 MPa and 4.6 GPa, which were 24.2 % and 52.3 % higher than that of GN/PA6T composite film, respectively. Such outstanding performance came from strong interfacial adhesion between GN and PA6T, induced by 2DPA nanosheets through hydrogen bonding and π-π interactions, which were confirmed by FTIR and UV–Vis measurements. Besides improving interfacial adhesion, 2DPA can also reduce the surface defect density of the GN through π-π conjugation. Both improved interfacial adhesion and reduced defects of GN contributed to the formation of electrically conductive and stress transfer pathways, which supported the excellent electrothermal and mechanical properties of 2DPA-GN/PA6T composite films. This study demonstrates an effective way to prepare high-performance graphene composites for electrothermal applications, with expected uses in aerospace, industry, and other technological fields.

Dielectric, low‐frequency noise and mechanical properties of hybrid carbon nanotubes/graphene nanoplatelets epoxy composites

AbstractThis study analyzes the electrical, microwave (26–37 GHz), low‐frequency (20 Hz–10 kHz) noise, and mechanical properties of epoxy hybrid composites filled with multi‐walled carbon nanotubes (MWCNT) and graphene nanoplatelets (GNP). The system's percolation threshold was around 0.25 vol.% MWCNT, while the electromagnetic properties were almost independent of GNP concentration. The composites are shown to be suitable for electromagnetic shielding in the 26–37 GHz range, with microwave absorption increasing as the total nanocarbon concentration rises. The electrical transport in these composites is governed by one‐dimensional Mott hopping at low temperatures (below 245 K) and redistribution effects above room temperature. The low‐frequency voltage noise spectra of the composites are predominant of the 1/f component, with noise spectral density proportional to Ub, where the exponent b is close to 2, indicating noise caused by resistance fluctuations. The optimal electromagnetic properties are near 0.5 vol.% MWCNT and 0.25 vol.% GNP concentrations. The tensile elastic modulus and yield strength showed the highest increases at 0.25/0.25 loading, with gains of 40.43% and 16.77%, respectively, compared to neat epoxy. Fracture toughness and energy release rate increased with adding 0.25 vol.% GNP, while Charpy impact strength improved with higher MWCNT loading.Highlights Percolation threshold in hybrid MWCNT/GNP composites is close to 0.25 vol.% MWCNT Low‐frequency voltage noise spectra of the composites are 1/f type

Bending of polymer films: a method for obtaining a compressive modulus of thin films.

Due to the advent of various foldable electric devices, it is becoming increasingly important to understand the bending properties of film materials. Bending of isotropic materials may be trivial if elastic deformation is small within a range of linear elasticity, which is often the case for bending. However, bending of polymer films, often used in recent foldable devices, may not be the case. Polymer films are frequently fabricated with stretching, which induces anisotropic orientation of molecular chains. In addition, there are many studies on bimodulus materials, which suggest the importance of the difference in tensile and compressive elastic moduli, i.e., the importance of elastic asymmetry, considering that bending involves compression and extension. In this study, we extended the standard linear elastic theory to include elastic anisotropy and elastic asymmetry and developed a method for obtaining compressive moduli of films, which cannot be obtained by a simple compression test because thin films under compression buckle at small strains. Our method is based on a bending test combined with a uniaxial tension test, which allows the measurement of Poisson's ratio in addition to Young's modulus, which are both anisotropic and asymmetric. To test our theory and method, we further performed experiments on biaxially stretched poly(ethylene terephthalate) (PET) films. As a result, we found non-negligible anisotropy in Poisson's ratio and non-negligible asymmetry (bimodulus) in tensile and compressive moduli. We further justify our framework by demonstrating a clear data collapse to show agreement between experiment and theory, clarifying limitations. Our results suggest the importance of elastic anisotropy and elastic asymmetry in bending of industrial films and give fundamental knowledge on this subject, which would be useful for applications. Such applications include the control of the position of the neutral plane and precise measurements of elastic moduli and Poisson's ratio, which are crucial, e.g., for the development of tough flexible electric devices and for the structural designs using compliant mechanisms.

Explainable Boosting Machine Learning for Predicting Bond Strength of FRP Rebars in Ultra High-Performance Concrete

Aiming at evaluating the bond strength of fiber-reinforced polymer (FRP) rebars in ultra-high-performance concrete (UHPC), boosting machine learning (ML) models have been developed using datasets collected from previous experiments. The considered variables in this study are rebar type and diameter, elastic modulus and tensile strength of rebars, concrete compressive strength and cover, embedment length, and test method. The dataset contains two test methods: pullout tests and beam tests. Four types of rebar, including carbon fiber-reinforced polymer (CFRP), glass fiber-reinforced polymer (GFRP), basalt, and steel rebars, were considered. The boosting ML models applied in this study include AdaBoost, CatBoost, Gradient Boosting, XGBoost, and Hist Gradient Boosting. After hyperparameter tuning, these models demonstrated significant improvements in predictive accuracy, with XGBoost achieving the highest R2 score of 0.95 and the lowest Root Mean Square Error (RMSE) of 2.21. Shapley values analysis revealed that tensile strength, elastic modulus, and embedment length are the most critical factors influencing bond strength. The findings offer valuable insights for applying ML models in predicting bond strength in FRP-reinforced UHPC, providing a practical tool for structural engineering.

Mechanical Stress-Oxidative Stress Axis: Biological Basis in the Vaginal Wall and Pelvic Floor Muscles of Rats with Simulated Birth Injury.

Vaginal delivery and resulting pelvic floor muscle (PFM) dysfunction are significant risk factors for pelvic floor dysfunction (PFD). Despite this, the biological basis underlying PFD after childbirth remain unclear. This study was aimed at assessing the early response of the vaginal wall and PFM to simulated birth injury (SBI) in rats. Forty female Sprague-Dawley rats were divided into four groups: control (sham operation), and 1, 4, and 14days post-injury. In the SBI groups, a catheter was inserted into the vagina with 130g of weight attached to the end, and the balloon was inflated to 5ml for 2h. Evaluation of vaginal tissues and PFMs included histological, immunohistochemical, Western blot, and uniaxial biomechanical testing. In the vaginal wall, the SBI group showed significantly lower COL1A1 expression and higher MMP-2 and MMP-9 expression. At 4 and 14days post-injury, there was a significant decrease in PFM fiber area and increased collagen content. The SBI group also exhibited significant increases in the expression of Nrf2, NQO1, HO-1, and SOD-2, indicating involvement of oxidative stress in both the vaginal wall and PFMs. Protein expression of Pax7 and MyoG, as well as the number of fibers with centralized nuclei, continued to increase significantly after SBI. Additionally, the vaginal wall of the SBI group showed a decreasing trend in tensile strength and elastic modulus, with a greater ultimate strain. Extracellular matrix remodeling, oxidative stress, decreased biomechanical properties, and muscle dysmyogenesis may collectively contribute to increased susceptibility to PFD development.

An assessment of PLA/wood with PLA core sandwich multilayer component tensile strength under different 3D printing conditions

Material extrusion is increasingly used to make functional parts in small batches that are challenging to produce with traditional machining. Also, intensive efforts are being made to develop new eco–friendly materials. This work investigates the strength of multilayer samples made in sandwich form with 4–5–4 layers of 0.3 mm layer thickness, externally with polylacticacid wood (PLA/wood, 61.5 % of specimens' material) and internally with pure PLA (38.5 % of specimens' material), under tensile loads. The intent is to investigate the possibility of manufacturing biocompatible components that take advantage of the excellent surface properties of wood externally and the durability properties of PLA internally. For this purpose, a designed experiment following the Taguchi L9 orthogonal array was prepared, and nine samples were fabricated: three with pure PLA, three with a sandwich PLA/wood–PLA–PLA/wood form, and three with composite PLA/wood form. Printing speed and temperature were varied during the experiment, and the results were examined using the analysis of means and residuals. Sandwich specimens improve tensile strength and elastic modulus by 100 % and 50 % compared to PLA/wood components while exhibiting slightly better surface roughness parameters, i.e., Ra and Rz, about ∼10 % lower values. Additionally, even if PLA parts showed better strength and surface texture than sandwich parts (∼100 % and ∼56 % higher tensile strength and elastic modulus), they had lower performance in terms of PLA–PLA/wood material ratio, i.e., 160 % more PLA than sandwich parts. The findings of this research, with the potential to design functional and sustainable new products with optimal performance, are significant and can be exploited in various industries.

High-modulus engineered cementitious composites: Design mechanism and performance characterization

Engineered cementitious composites features with high tensile performance while relatively weak compressive stiffness. This study endeavors to address the inherent trade-off between tensile properties and elastic modulus in conventional Engineered Cementitious Composites (ECC). Utilizing the distinctive characteristics of iron ore aggregates, known for their relatively stiff nature, smooth surface and rounded shape, an Iron Sand-based ECC (IS-ECC) emphasizing both high elastic modulus and ductility is formulated. Guided by micromechanical design theory and multiscale homogenization model, this study systematically explores the impacts of aggregate types, water-to-binder (w/b) ratios, sand-to-binder (s/b) ratios, and sand particle sizes on ECC properties. Compared with Quartz Sand-based ECC (QS-ECC), IS-ECC exhibits notably enhanced matrix fluidity and elastic modulus, reduced matrix toughness, and more robust strain-hardening behavior. The proposed three-level multiscale homogenization model accurately predicts the elastic modulus of ECC and provides insights into the underlying mechanism contributing to the enhanced elastic modulus of IS-ECC. With a resulting high elastic modulus of 33.3–48.6 GPa and superior tensile properties, IS-ECC holds promise for widespread applications in structural engineering.

A multi-scale modeling method for tensile properties of strain-hardening cementitious composites

The synergistic design of components of Strain-Hardening Cementitious Composites (SHCC) based on micromechanics is the critical to realize its high strength and ductility. We have developed a mesoscale model for revealing effects of mesoscopic parameter of SHCC on its multiple cracking behavior. However, the heterogeneity of mortar in SHCC, which may influence the saturated multiple cracking, was usually absent in the existing mesoscale model. In this paper, a sub-mesoscale model of mortar considering the fine aggregates, hydrated cement paste, and interfacial transition zones (ITZ) are introduced into the previous SHCC mesoscale model. A parameter transfer method linking these two scales is proposed. By linking them, the parameter design of SHCC of different scales can be considered comprehensively. The proposed model is validated by the three-point bending test and uniaxial tensile test of SHCC. The effects of fine aggregate volume, tensile strength of hydrated cement paste and tensile strength of interfacial transition zone on the mechanical behavior are parametrically analyzed via the validated model. The results show that the increase of the volume content of fine aggregate will reduce the tensile strength and elastic modulus of SHCC mortar matrix, while the strength of hydrated cement paste has a significant increase in the first crack stress of SHCC, and the ITZ strength mainly affects the elastic modulus of SHCC mortar. The developed model provides a reference for the material optimization design of SHCC.

Molecular dynamics study of mechanical stability of Ti4C3 MXene subjected to chirality, temperature, strain rate, and point-vacancy for Lithium-ion batteries

Two-dimensional Ti4C3 MXene has recently emerged as a promising electrode for Lithium-ion batteries (LIBs) because of its outstanding ion-transport abilities and high Li-absorbability. This study employed molecular dynamics simulation to explore the mechanical stability of Ti4C3 MXene subjected to various temperatures, strain rates, and vacancy concentrations. A slightly superior tensile strength and elasticity modulus have been observed along zigzag directions, measuring 148.14 GPa and 29.17 GPa, respectively. On the other hand, armchair-oriented Ti4C3 MXene shows a considerably greater fracture strain of 0.259 due to its strain-hardening tendency at lower temperatures. Elevated temperature decreases both fracture strength and fracture strain, which is opposite to the effect of strain rate. Armchair loading has been revealed to be more sensitive to strain rate than its counter direction. Unlike temperature and strain rate, point vacancy significantly deteriorates the elastic modulus of Ti4C3 MXene. Carbon vacancies are more probable than titanium vacancies, which have less formation energy. The atomistic deformation profile supports the predicted values of fracture strain from stress-strain behavior. This in-depth study offers a detailed understanding of the mechanical behavior of Ti4C3 MXene under diverse circumstances, which will aid further experimental study and be beneficial for adopting Ti4C3 as anode materials in LIBs.

Deposition of cellulose acetate coatings on titanium substrates by electrospraying for biomedical applications

Functional coatings have gained interest in the field of metal implants, as they reduce the complications associated with mechanical parameters and promote its integration. Among the other coating production methods electrospraying remains very little researched for this application despite its advantages. This study investigates the feasibility of the electrospraying method for the production of coatings with extended mechanical properties. Six biocompatible cellulose acetate coatings from solutions of (6–16) wt% were fabricated on titanium substrates using electrospraying. The layer thickness varied between the samples from 1.8 to 16.4 μm, while the roughness varied between the samples from 1 to 2 μm. Bending tests showed that the maximum elongation of the coatings between the samples gradually decreased from 40.00 % to 13.33 %. Stretching of detached films revealed decrease in tensile strength and elastic modulus from 58 to 30 MPa and from 2082 MPa to 978 MPa, respectively. Pull-off tests showed coatings adhesion strength of 0.8–1.4 MPa after sandblasting. Investigation of chemical composition and structure of the coatings using X-ray photoelectron spectroscopy, Fourier-transformed infrared and Raman spectroscopy showed results typical of cellulose acetate materials and confirmed that no structural changes took place during electrospraying. X-ray diffraction analysis revealed that the coatings obtained are amorphous. The coatings produced by the fast and cost-effective electrospraying process have competitive overall properties, while the coatings prepared from 10 and 12 wt% solutions are most suitable for use on titanium surfaces due to their mechanical properties and uniformity.

Fiber-Reinforced Thermoplastic Sucker Rods Provide Artificial Lift Efficiencies

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 23949, “Fiber-Reinforced Thermoplastic Sucker Rods Providing High-Strength, Lightweight, Low-Cost, and Environmentally Responsible Artificial Lift Efficiencies,” by Jeff Saponja, SPE, Oilify, and Corbin Coyes, SPE, and Michael Conner, SPE, Q2 Artificial Lift Services. The paper has not been peer reviewed. Copyright 2024 International Petroleum Technology Conference. _ The complete paper focuses on the development of fiber-reinforced thermoplastic (FRTP) sucker rods, highlighting their potential advantages and challenges, for rod pumping (in general) and for offering an earlier transition from electrical submersible pump (ESP) pumping or gas lifting to reliable deep high-rate rod pumping. A unique feature of an FRTP composite rod is its remarkably high shear failure resistance compared with that of a thermoset composite rod. A high shear-failure resistance means the rods have compressional loading tolerance and that an entire sucker rod string could be comprised of FRTP sucker rods. Introduction Sucker rods made from steel are relatively heavy. Extensive well-specific designs require tapering of rod strings to optimize the overall sucker rod string weight relative to the strength and fatigue requirements and consideration of the dynamic loadings from accelerations and decelerations of the rods and fluids, frictional effects, and structural or power limitations of the pump jack or unit at surface. Steels suffer from corrosion risks. Corrosion, which rapidly can accelerate fatigue failure, often is the root cause of sucker rod failure. Fiber-reinforced composites (i.e., fibers surrounded by or wetted by a resin matrix) have gained considerable popularity because they can be tailored to have outstanding mechanical, thermal, and physical properties, and have superior material mechanical properties to metal. The fatigue behavior of composite materials and structures is complex because composites fail by a series of, or collection of, damage mechanisms, including fiber breakage, matrix cracking, fiber/matrix debonding, delamination, and the effect of shear-induced damage on cracks. Cracking can be slowed somewhat if the reinforced fibers are of high stiffness. Composite materials can offer a lower environmental footprint over their entire life cycle. They can require less energy to manufacture, thereby reducing CO2 emissions. A high strength/weight ratio offers less energy consumption during operational use, further reducing CO2 emissions. Composite materials can be recycled and reused. Composite sucker rods, in the form of thermoset fiberglass sucker rods, have offered a high strength/weight ratio with greater corrosion tolerance, but they are too stretchy from a low glass fiber tensile modulus of elasticity for deep high-rate rod pumping and when a high production-rate decline is likely. This limitation results in a large bottomhole pump-stroke variability as operating conditions change. Such rods have low tolerance to compressional and impact loads, forcing a larger proportion of a sucker string to remain as steel. They are also more costly than steel rods. For sucker rod pumping, an ideal composite rod should tolerate compressional loads and feature high impact resistance and high fatigue endurance with an ability to limit or control crack formation. A composite material that potentially offers these important sucker rod properties is FRTP.

Composites with Synergistically Enhanced Thermodynamic and Mechanical Properties for Geothermal Heat Exchangers

Geothermal energy, derived from the radioactive decay of elements within the Earth's core, is a renewable and clean energy source. The extraction of geothermal energy primarily depends on ground heat exchangers. To address the issue of incompatibility between corrosion resistance, high thermal conductivity, and mechanical performance in current ground heat exchangers, this study develops composites (PEPOE/SCA@SiC) composed of high‐density polyethylene (HDPE) modified with toughener polyethylene‐octene copolymer elastomer (POE) and silicon carbide (SiC) crystals modified with γ‐aminopropyltriethoxysilane (SCA). HDPE offers excellent corrosion resistance, SiC crystals provide efficient phonon transport, and SCA improves the interface compatibility of the composite. The thermal conductivity of PEPOE/SCA@SiC reaches 3.83 W m−1K−1, with a maximum tensile strength of 20.3 MPa, a tensile elastic modulus of up to 498 MPa, and a maximum bending stress of 22.2 MPa with a bending elastic modulus of 561 MPa. Corrosion resistance tests indicate no signs of corrosion in PEPOE/SCA@SiC when exposed to geothermal simulation fluids at 90 °C for 30 days. This study demonstrates that PEPOE/SCA@SiC composites have substantial potential for application in ground heat exchangers, offering promising prospects for advancing sustainable use of geothermal energy and environmental protection.

Preparation and Application of a Novel Liquid Oxygen-Compatible Epoxy Resin of Fluorinated Glycidyl Amine with Low Viscosity

A liquid oxygen-compatible epoxy resin of fluorinated glycidyl amine (TFEPA) with a low viscosity of 260 mPa·s in a wide range of temperatures, from room temperature to 150 °C, was synthesized and used to decrease the viscosity of phosphorus-containing bisphenol F epoxy resins. And the forming process and application performances of this resin system and its composite were investigated. The viscosity of the bisphenol F resin was decreased from 4925 to 749 mPa·s at 45 °C by mixing with 10 wt.% TFEPA, which was enough for the filament winding process. Moreover, the processing temperature and time windows were increased by 73% and 186%, respectively. After crosslinking, the liquid oxygen compatibility was preserved, and its tensile strength, elastic modulus, and breaking elongation at −196 °C were 133.31 MPa, 6.59 GPa, and 2.36%, respectively, which were similar to those without TFEPA. And the flexural strength and modulus were 276.14 MPa and 7.29 GPa, respectively, increasing by 21.73% in strain energy at flexural breaking, indicating an enhanced toughness derived from TFEPA. Based on this resin system, the flexural strength and toughness of its composite at −196 °C were 862.73 MPa and 6.88 MJ/m3, respectively, increasing by 4.46% and 10.79%, respectively.

Thermo-mechanical responses of rubber concrete post-exposure to elevated temperatures

This manuscript introduces a hybrid approach merging the Alternating Direction Implicit (ADI) method with the Crank Nicolson scheme, renowned for its unconditional stability, for forecasting the thermo-mechanical responses of rubber concrete experiencing thermal shock. Various proportions of rubber aggregate (0%, 10%, 20%, and 30%) are investigated under a constant humidity level (3%). The governing equation for coupled thermo-mechanical phenomena, derived from the heat conduction equation, is delineated, followed by discretization employing the proposed methodology. A comparative analysis between the analytical solution, featuring temperature and time-dependent constants, and the numerical outcomes is conducted to validate the proposed algorithm. Additionally, the impact of temperature on mechanical parameters like tensile strength, compressive strength, and elastic modulus is deliberated. The findings, including 3D contour plots and the temporal evolution of temperature and each mechanical parameter, affirm the capability of our numerical framework in anticipating and scrutinizing the thermo-mechanical dynamics of rubber concrete under fire-induced loading conditions.

Atomistic study of selenium doping effects on the mechanical properties of zinc-blende and wurtzite CdTe nanowires

CdSexTe1–x semiconductor materials, having potential to be used to design dependable and reproducible nanowire devices, require an extensive study of their mechanical behaviors. The uniaxial tensile deformation mechanism of CdSexTe1–x nanowires (NWs) with different Se dopant concentration are yet to be explored. By integrating theoretical analysis with computational simulation, this research demonstrated that Se doping in CdTe NWs influences the mechanical response and failure modes. Ultimate tensile strength (UTS) and elastic modulus (EM) were studied for both zinc-blende (ZB) and wurtzite (WZ) structures with different crystal orientations. The findings revealed that these mechanical properties increase linearly with increasing Se concentration in all cases. In addition, the WZ structures exhibited similar mechanical properties under both zigzag and armchair loadings, unlike the ZB structures, which exhibited a strong dependence on the crystal orientation. The [111]-oriented ZB structures showed the highest EM and UTS whereas [100]-oriented ZB structures showed lowest EM and UTS. The failure mechanism was explored for CdSe50Te50 to underscore the influence of the dopant on the NWs failure for tensile loading. In both the cases of WZ structure, the failure planes were perpendicular to the loading direction. Furthermore, the failure plane varied with the Se content in ZB CdSexTe1–x. Atomic coordination and bond length affected by doping defined the alterations of mechanical properties and the preferred modes of failure. The significance of the interaction between doping elements and nanowire structures offers insights that unite material science and mechanics, contributing to the scientific understanding of solid materials’ behavior.

Development of hydroxyapatite/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/gelatin composite nanofibers to improve bone‐forming cell proliferation and mineral deposition

AbstractCalcium phosphate hydroxyapatite (HA) was successfully incorporated into poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/gelatin (PHBV/GEL) nanofibers through an electrospinning process in a hexafluoroisopropanol solvent (HFIP). The PHBV/GEL was electrospun and collected using a rotating metallic network to develop highly ordered nonwoven mats. The effects of HA addition on the morphologies of the obtained fibers were investigated using SEM. The average diameter of the fibers ranged around 700–900 nm, depending on the HA content. From a mechanical perspective, the addition of HA nanoparticles showed variations in tensile strength and elastic modulus values. The lowest tensile strength measured for neat PHBV/GEL was 0.37 ± 0.08 MPa with an elastic modulus of 9.45 ± 0.65 MPa, whereas the highest tensile strength reported for 5% HA‐loaded PHBV/GEL mats was 1.1 ± 0.4 MPa with an elastic modulus of 16.9 ± 0.39 MPa. In addition, cell viability, and mineral deposition were also studied using MC3T3‐E1 pre‐osteoblasts. The in vitro experiment results showed that the HA loaded‐PHBV/GEL mats provide optimal conditions for cell growth and osteogenic differentiation of MC3T3‐E1 cells. This study reveals the potential of PHBV/GEL/HA matrices in the development of novel guided bone‐regeneration (GBR) membranes for orthopedic and craniomaxillofacial surgery, by providing favorable structural features for attachment, growth, and differentiation of osteoblast cells.Highlights Simple and cheap electrospinning strategy toward network‐like fibrous mats. Microstructure, mechanical, and biological features were evaluated. Electrospun PHBV/GEL/HA promoted calcium phosphate deposition by MC3T3‐E1 cells.

Bioinspired Bouligand-Structured Cellulose Nanocrystals/Poly(vinyl alcohol) Composite Hydrogel for Enhanced Impact Resistance.

Impact-protective materials are gaining importance because of the widespread occurrence of impact damage. Hydrogels have emerged as promising candidates owing to their lightweight and flexible nature. However, achieving soft impact-resistant hydrogels with exceptional stiffness, strength, and toughness remains a challenge. Inspired by the Bouligand structure found in the smasher dactyl club of stomatopods, we propose a straightforward multiscale hierarchical structural design strategy. This strategy integrates self-assembly and salting-out techniques to enhance the impact resistance of soft hydrogels. Rigid cellulose nanocrystals (CNCs) self-assemble into Bouligand-like structures within soft poly(vinyl alcohol) (PVA) matrix via supramolecular interactions. This rational structural design combines the CNC Bouligand structure with a cross-linked network of soft PVA crystalline domains, resulting in a composite hydrogel with impressive mechanical properties: high tensile fracture strength (30.2 MPa), elastic modulus (62.7 MPa), and fracture energy (75.6 kJ m-2), surpassing those of other tough hydrogels. Moreover, the multiscale hierarchical structure facilitates various energy dissipation mechanisms, including crack twisting, tortuous crack paths, and PVA chain orientation, resulting in notable force attenuation (80.4%) in the composite hydrogel. This biomimetic design strategy opens new avenues for developing soft and lightweight impact-resistant materials.