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The low liquid limit silty soil in the North China plain area is generally unsuitable for direct use as roadbed and slope soil. In order to improve the performance of low liquid limit silty soil, xanthan gum was used as an improver. Through a series of tests, the improvement effect of xanthan gum on low liquid limit silty soil was studied. The test results showed that Xanthan gum as an improver could significantly improve the unconfined compressive strength of silty soil. With the increase in dosage and curing age, the unconfined compressive strength of improved silty soil continued to improve and eventually tended to stabilize. The optimal dosage and curing period were 2% and 7 days, respectively. In addition, Xanthan gum could greatly improve the permeability and disintegration of low liquid limit silty soil. The permeability coefficient of improved silty soil with a content of 0.75% Xanthan gum and a 7-day curing period was 4.73 × 10−4 m·s−1, which was only 1.10% of that of plain silty soil at the same curing period. After immersion in water for 12 h, the soil only experienced slight disintegration. The scanning electron microscope image showed that the gel generated by the hydration reaction of Xanthan gum could improve the compactness and integrity of the soil by filling the voids, thus significantly improving the mechanical and hydraulic properties of the low liquid limit silty soil. [ABSTRACT FROM AUTHOR]

This research paper focuses on the use of solid biomass waste, specifically a combination of Polyalthia longifolia seed (PLSF) and graphite (GH) powder, as reinforcements in vinyl ester (VE) composites. The composites were produced via the hand layup method, with the filler concentration varying from 0 to 15 wt% of PLSF and 0–9 wt% of graphite. The objective was to examine the influence of the hybrid filler on the mechanical characteristics of the composites. The mechanical properties of composites prepared from P. longifolia seeds and graphite powder were experimentally characterized. These properties included tensile strength, flexural strength, impact resistance, and hardness. The hybrid composite had a maximum tensile strength of 48.4 MPa, and its tensile modulus was 1.66 GPa. The hybrid filler at 15% wt% of PLSF and 6% of graphite has the highest flexural strength, which is around 148 MPa. The ultimate impact strength and hardness were measured to be 41.3 kJ/m2 and 44.5, respectively, after the addition of 15 and 6 wt% of hybrid filler. In comparison to neat vinyl ester resin, the PLSF/GH‐VE composites exhibited an increase in tensile, flexural, impact, and hardness of 2.69, 1.82, 3.03, and 1.59 times, respectively. Hybrid composite surfaces were analyzed using scanning electron microscopes to determine surface characteristics and fractured surfaces. In addition, the PLSF/GH‐VE composites have been utilized in the production of components for four‐wheelers. Highlights: Investigated the impact of hybrid filler‐reinforced vinyl ester composites.Mechanical and thermal properties were experimentally characterized.Surface characteristics and fractured surfaces were examined.PLSF/GH‐VE composites are used in producing components for four‐wheelers. [ABSTRACT FROM AUTHOR]

3D printing has witnessed a remarkable surge in popularity due to its flexibility in design and adaptability as a manufacturing technique to nearly each industrial area. This study focuses on harnessing the technological versatility of 3D printing by utilizing both standard poly lactic acid (PLA) and copper powder‐doped PLA to fabricate intricate structures through a layer‐by‐layer additive manufacturing process. The other innovation introduced here lies in the postprocessing step, which involves salt remelting. The mechanical properties of 3D‐printed standard test specimens undergo comprehensive assessment, encompassing bending and tensile evaluations, hardness measurements, density assessments, dimensional stability analyses, and wear resistance examinations. Utilizing copper powder‐doped PLA for the initial and final layers in XYZ‐oriented prints enables multimaterial printing, resulting in an ≈14% increase in tensile strength. Subsequently, subjecting this multimaterial composite to salt remelting elevates the strength enhancement to ≈16%, accompanied by a significant boost in rigidity by reducing voids in cross‐sectional area. In addition, scanning electron microscope images are captured, allowing for a detailed morphological analysis, which is then correlated with the findings of the various tests performed. This research unveils the potential of 3D printing technology in crafting materials with tailored mechanical properties, advancing its applicability in numerous industrial sectors. [ABSTRACT FROM AUTHOR]

Using Camellia oleifera shell as raw materials to preparative SiC ceramics by warm‐press forming and sintering is proposed in this paper. Warm‐press forming before preparing for the C. oleifera shell‐based SiC ceramics is beneficial to obtain the internal uniform and suitable pore structure of the cylindrical sample. Thermogravimetric analysis with differential scanning calorimetry was applied to analyze the pyrolysis behavior of C. oleiefra shell and phenolic resin. The scanning electron microscope and X‐ray diffraction were used to investigate the properties of C. oleifera shell‐based SiC ceramics. Then, the response surface method was applied to establish a multivariate prediction model based on the process parameters of warm‐press forming. And the regression equations of porosity and bending strength of COS‐SiC are obtained. The result demonstrated that the predicted and experimental values can be in good agreement for the model. By comparing the F‐value, it is found that the forming temperature and pressure during the process of warm‐press forming have a more significant influence on the porosity and bending strength of SiC ceramics. The optimization process parameters were obtained as follows: forming temperature 153°C, pressure 35 MPa, and holding time 30 min. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to evaluate the efficiency of using some polymers at different concentrations in the consolidation of vegetable-tanned leather artifacts. Design/methodology/approach: New vegetable-tanned leather samples were prepared. The consolidants used were polyacrylamide (PAM) and polymethyl methacrylate/hydroxyethyl methacrylate (MMA-HEMA). Accelerated heat aging was applied to the untreated and treated samples. Analytical techniques used were Fourier transform infrared spectroscopy (FTIR), digital microscope, scanning electron microscope (SEM), change of color and mechanical properties. Findings: The characteristic FTIR bands showed the effect of accelerated heat aging on the molecular structure of the studied samples, but treated and aged treated samples used were better than aged untreated samples. Microscopic investigations (digital and SEM), and mechanical properties proved that 2% was the best concentration for polymers used. The change in the total color difference of the treated and aged treated samples was limited. Originality/value: This study presents the important results obtained from PAM and poly(MMA-HEMA) used for the consolidation of vegetable-tanned leather artifacts. The best results of the studied polymers can be applied directly to protect historical vegetable-tanned leathers. [ABSTRACT FROM AUTHOR]

In this article, the effect of Ce element on the microstructure and mechanical properties was studied by Ce addition to the hot‐formed steel. Scanning electron microscope and energy dispersive spectrometer (SEM‐EDS) was used to analyze the improvement effect of Ce on inclusions and the effect of inclusions on fracture behavior; Electron back scattering diffractometer (EBSD) was used to analyze the refinement and strengthening effect of Ce on martensitic grains; transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) was used to analyze the microstructure strengthening effect and microalloying effect of solid solution Ce in hot‐formed steel. Through a systematic analysis of mechanical properties and microstructure, the mechanism of Ce enhances the strength and elongation of hot‐formed steel was clarified. Besides, this work provides a research basis for further improving the safety and machinability of hot‐formed steel. [ABSTRACT FROM AUTHOR]

One of the challenges of storing hydrogen in saline aquifers is the possible geochemical reactions between host rock, formation solution, and hydrogen. This study investigated the effect of hydrogen treatment on the mechanical properties of sandstone samples from Hulett member of Sundance Formation, a potential underground hydrogen storage host in Wyoming, USA. Cylindrical specimens were treated with brine, brine+50%H 2, and brine+100%H 2 for two weeks at a pressure of 15 MPa and a temperature of 83 °C. X-ray diffraction (XRD), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), uniaxial compression, and triaxial compression tests were conducted on specimens. Results showed that specimens treated with brine+50%H 2 and brine+100%H 2 , on average, exhibited 24 and 41% lower peak strength, respectively, compared to that of specimens treated with the brine. XRD results showed a decrease in dolomite and clay content of specimens after exposure to hydrogen, causing degradation of the mechanical and elastic properties of the specimens. • The effect of hydrogen on the mechanical properties of Hulett sandstone was investigated. • Dolomite and clay dissolution was observed after the treatment with hydrogen. • Specimens treated with hydrogen on average showed 41% lower strength. • An average 43% decrease in elastic modulus was observed after hydrogen treatment. [ABSTRACT FROM AUTHOR]

This paper examines the lithology, pore throat, and fluid characteristics of the reservoir in Liaohe Oilfield Block 3624, using group V rocks as an example, combining a high-temperature and high-pressure reaction still with other equipment such as a rock mechanics tester and a scanning electron microscope. This study also designs and develops three controlled variable experiments, including the subcritical steam reservoir rock dissolution experiment, the subcritical steam reservoir rock mineral composition transformation experiment, and the subcritical steam reservoir rock mineral mechanical property experiment, also making clear the rule of change on the part of the rocks in the deep and heavy oil reservoirs after the injection of subcritical steam. Experimental results reveal the following: (1) Steam causes the dissolution of rocks, and when the steam temperature is in the subcritical region, dissolution is visible. After a 350 °C subcritical steam treatment, the relative melting temperatures of the components of rock materials are substantially greater than the melting point of the cement holding them together, causing the cement to significantly dissolve and a secondary crack network to emerge. (2) The mineral composition of the rocks changes as a result of elevated temperatures, with various mineral transformation trajectories being recorded after various steam treatments. Montmorillonite in reservoir rocks is converted into minerals like illite and chlorite in the subcritical steam temperature range. Another element influencing the creation of secondary cracks on rock surfaces is the reciprocal transformation of minerals, which alters the cohesiveness among mineral components. (3) Rocks suffer thermal damage and changes to their mechanical characteristics as a result of high-temperature steam dissolution and mineral transformations; the severity of these changes increases with the steam temperature. [ABSTRACT FROM AUTHOR]

In this present study, the fused deposition modeling (FDM) method was used to fabricate the composites. Before three-dimensional (3D) printing, samples were designed according to the ASTM D256, D790 and D3039 standards for impact, flexural and tensile tests, respectively, using Onshape software before conversion to an STL file format. Afterward, the digital file was sliced with infill densities of 60%, 80%, and 100%. The composite samples contained chopped carbon fiber (cCF) and poly lactic acid (PLA), as reinforcement and matrix, respectively. The cCF/PLA (simply called cCFP) filaments were printed into various cCFP composite (cCFPC) samples, using a Viper Share bot 3D machine with different infill densities before the aforementioned mechanical testing. The tensile strength of cCFP were obtained as 25.9MPa, 26.9MPa and 34.75MPa for 60%, 80% and 100% infill density cCFP samples, respectively. Similarly, the flexural strength of cCFP were obtained as 11.8MPa, 12.55MPa and 18.4MPa and impact strength was 47.48kJ/m2, 48.45kJ/m2 and 48.96kJ/m2 for 60%, 80% and 100% infill density cCFP samples, respectively. The fractured/tested samples were examined and analyzed under a scanning electron microscope (SEM) to investigate the presence of fiber and void in the tensile sample. Based on the experimental results, it was evident that a high infill density of 100% with the highest reinforcement exhibited maximum impact strength, tensile and flexural strengths and moduli when compared with other lower carbon content of cCFPC samples. Therefore, the optimal 3D-printed cCFPC sample could be used for engineering application to benefit from properties of the polymer matrix composite materials and possibilities through additive manufacturing (AM). [ABSTRACT FROM AUTHOR]

A composite resin containing eggshell particles for the additive manufacturing according to the stereolithography (SLA) printing technology was studied. First, the viscosity properties of the eggshell-particle-reinforced resin were determined. Then, the effect of particle wt% on the hardness, tensile, and compressive behaviors of the composite specimens were investigated. Besides, the optical microscopy images of unreinforced and reinforced 3D printed composites were scrutinized. The cross-sections of the composite were analyzed by the energy dispersion spectrometry and optical and scanning electron microscopes (EDS/SEM) in order to examine its structure in detail. To analyze the damping properties and the elastic modulus determined in tension and free vibration tests were also carried out. [ABSTRACT FROM AUTHOR]

Ultra-high-rise buildings require high concrete bearing capacity. Ordinary concrete often fails to meet the project requirements. Admixture of admixtures in concrete is a means of solution. Currently, studies on the incorporation of basalt fiber (BF) and fly ash (FA) in concrete are relatively mature. However, research on incorporating nano-Titanium Carbide (nano-TiC) in concrete is still relatively scarce, which has a lot of room for development. To further improve the mechanical properties of concrete, BF, and FA synergized with nano-TiC were incorporated into concrete to produce TBF concrete in this study. And Response Surface Methodology (RSM) was used to optimize the mechanical properties of concrete. The collapse and compressive deformation damage characteristics of concrete were analyzed. The microstructure of the cement matrix was analyzed by the SEM (Scanning Electron Microscope). An optimization model of the TBF concrete craving function was developed. Optimized ratios with compressive, split tensile, and flexural strengths as response objectives were obtained, and the accuracy of the optimized ratios was investigated using the same experimental conditions. The results of the study showed that FA increased the collapse of concrete, while nano-TiC and BF decreased the collapse of concrete. Under uniaxial compression, nano-TiC, FA, and BF together incorporated into concrete can improve its compressive damage state. Moderate amounts of nano-TiC, BF, and FA could improve the mechanical properties of concrete. Their optimal mixing ratio admixtures were 0.88%, 0.24%, and 5.49%, respectively. And the measured values under the same conditions were compared with the predicted values. The maximum difference in compressive strength was 6.09%. The maximum difference in split tensile strength was 7.14%. The maximum difference in flexural strength was 8.45%. This indicated that the accuracy of the RSM optimization model was good. A moderate amount of nano-TiC, FA, and BF could improve the densification of concrete. [ABSTRACT FROM AUTHOR]

The tensile behavior of a flexible epoxy resin reinforced with knitted reinforcements from various fiber materials was comprehensively studied in the wale and course direction. By measuring dry yarns, temperature‐treated yarns, dry knitted fabrics and flexible composites, the effect of the fiber material and the knitted fabric on the tensile properties was analyzed. The interlock knit structure strongly affected the deformation behavior of the flexible composites which differed significantly from the dry knitted fabrics. The deformation behavior of the flexible composites was monitored using digital image correlation which revealed the formation of cracks and high local strain differences in the course direction for all fiber materials. This was linked to fiber‐matrix debonding by scanning electron microscope observations. In the wale direction, the deformation of the knitted structure under tensile load led to plastic deformation of the matrix material. Overall, with yarns from recycled thermoplastic fibers, a higher maximum stress and strain at break was achieved compared to bio‐based fibers. However, irreversible damage occurred for all fiber materials at similar strain values. Highlights: Tensile tests on yarns, knitted fabrics and flexible composites.Investigation of the effect of fiber material on mechanical properties.High local strain differences in composites due to knitted structure.Fiber‐matrix debonding in course direction.Plastic deformation of the matrix material in the wale direction. [ABSTRACT FROM AUTHOR]

HTW-50 solid wire CO2 gas-shielded arc spot welding and resistance spot welding techniques were utilized to fabricate multiple sets of HRB400E hot-rolled ribbed seismic reinforcement cross-spot welded test specimens. These specimens were subjected to unidirectional tensile testing to investigate the impact of cross-spot welding on the mechanical properties of the steel bars. Chemical composition analysis and hardness testing were conducted on the brittle fracture test specimens using a metallurgical microscope, scanning electron microscope, and Rockwell hardness tester, among other related equipment. The brittle fracture mechanism of the cross-welded test specimens was subsequently examined from both macroscopic and microscopic perspectives. The results indicate that cross-spot welding of large-diameter rebars does not affect their strength. However, 80% of the test specimens exhibited brittle fractures that occurred at the weld point. Moreover, the elongation of the brittle fracture specimens was lower than the standard value, indicating a need for improved toughness. In comparison to CO2 gas-shielded arc spot welding, resistance spot welding had a lesser impact on the elongation of the steel bars and demonstrated greater stability. The test specimens exhibited fractures primarily at the welded area, where only a minimal amount of toughness was observed. Disintegration steps and river-like patterns were also observed at the weld, suggesting a mechanism of disintegration fracture. Additionally, tempered martensite was detected in the heat-affected zone, rendering the bars brittle, and making them prone to fracture at the weld. [ABSTRACT FROM AUTHOR]

This research paper presents a comparative experimental study on the impact of zinc oxide and zirconium dioxide nanomaterials on the chemical, mechanical, and crystalline properties of epoxy resin (diglycidyl ether of bisphenol-A). Nanomaterials were incorporated into the epoxy resin at three different concentrations (4%, 6%, and 8%) by weight. Results indicated enhanced properties of the epoxy resin, including tensile and compressive strengths, as well as improvements in chemical and crystalline characteristics, assessed through scanning electron microscope (SEM) and Fouriertransform infrared spectroscopy (FTIR). Notably, zirconium dioxide exhibited superior performance across all properties, enhancing tensile and compressive strengths by 67% and 50%, respectively. Zinc oxide, at the same concentrations, led to a 50% increase in tensile strength and a 40% increase in compressive strength. These outcomes were observed at the highest concentration (8%wt) of both nanomaterials and the pure epoxy resin. The presence of nanomaterials at this ratio promoted greater cohesion within the composite, as evidenced by SEM images of selected samples. SEM analysis highlighted the pivotal role of ZrO2 nanoparticles in improving epoxy integration, surface quality, crystallization, and imperfection removal, crucial factors for enhancing composite materials. FTIR analysis of the resin containing ZrO2 nanoparticles revealed shifts and alterations in peaks, indicating successful nanoparticle-epoxy interaction, resulting in notable structural changes. [ABSTRACT FROM AUTHOR]

Large-diameter polyvinyl alcohol (PVA) fiber has a broad application prospect in the field of reinforcing geomorphic building materials owing to its large diameter and excellent mechanical properties. In this work, PVA2499 polymer was used as the raw material, DMSO/H2O as the hybrid solvent, and the staged heating approach was adopted to obtain high solid content of spinning solutions, and then a series of large-diameter medium-strength PVA fibers with different solid contents of spinning solutions (SCS) were prepared by dry-wet spinning, and the Fourier transform infrared spectroscopy (FTIR), scan electron microscope (SEM), differential scanning calorimetry (DSC), thermal analysis (TGA), X-ray diffractometer (XRD) and electronic universal testing machine were performed to explore the effect of the SCS on the structure and performance of PVA fiber. The results displayed that with the increase of the SCS, the -OH stretching vibration absorption peak of PVA fiber moved from 3276 cm−1 to 3262 cm−1; The tensile strength, initial modulus, the crystallization and orientation of PVA fibers all increased first and then decreased. Especially, when the SCS was 23.5wt%, the diameter of the PVA fiber was 110.6 ± 6.0 μm (124.8 ± 6.2 dtex), the tensile strength was 7.0 ± 0.3 cN/dtex, the initial modulus was 106.2 ± 10.3 cN/dtex, the crystallization and the orientation were 49.6% and 96.8%, respectively. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of stir‐casting process parameters, including stirring speed, stirring time, and weight % of the ceramic microsphere, on the fabrication of an aluminium 6061‐ceramic microsphere composite. Experiments are conducted using a full‐factorial design approach to determine the effect of variables on mechanical properties. A field effect scanning electron microscope is used to analyze the fracture surfaces of the test specimen. Further, the results are subjected to the Anderson‐darling normality test to validate the accuracy of the model, and finally, an analysis of variance is performed to identify the most significant parameters that affect the mechanical properties. The results confirm the validity of the designed experimental model for enhancing the mechanical properties of the aluminium 6061‐ceramic microsphere composite. The optimum mechanical properties are attained for a stirring speed of 600 min−1, stirring time of 15 min, and 5 weight % of reinforcement. Furthermore, the weight percentage of the ceramic microsphere increase, the ductility of the composite decreases while its strength and hardness increase. Finally, the analysis of variance shows that all parameters significantly impact the mechanical properties of the designed composite. [ABSTRACT FROM AUTHOR]

This paper investigates making an injection mouldable conductive plastic formulation that aims for conductivity into the electromagnetic interference (EMI) shielding range, with good mechanical properties (i.e., stiffness, strength, and impact resistance). While conductivity in the range (electrostatic charge dissipation) and EMI shielding have been attained by incorporating conductive fillers such as carbon black, metals powders, and new materials, such as carbon nanotubes (CNTs), this often occurs with a drop in tensile strength, elongation-to-break resistance, and impact resistance. It is most often the case that the incorporation of high modulus fillers leads to an increase in modulus but a drop in strength and impact resistance. In this work, we have used short carbon fibres as the conductive filler and selected a 50/50 PBT/rPET (recycled PET) for the plastic matrix. Carbon fibres are cheaper than CNTs and graphenes. The PBT/rPET has low melt viscosity and crystallises sufficiently fast during injection moulding. To improve impact resistance, a styrene-ethylene-butadiene-styrene (SEBS) rubber toughening agent was added to the plastic. The PBT/rPET had very low-impact resistance and the SEBS provided rubber toughening to it; however, the rubber caused a drop in the tensile modulus and strength. The short carbon fibre restored the modulus and strength, which reached higher value than the PBT/rPET while providing the conductivity. Scanning electron microscope pictures showed quite good bonding of the current filler (CF) to the PBT/rPET. An injection mouldable conductive plastic with high conductivity and raised modulus, strength, and impact resistance could be made. [ABSTRACT FROM AUTHOR]

The aim of the present work was to evaluate six commercially available abutment screws by characterising roughness parameters, microstructure and mechanical properties. Six abutment screws from each implant system, were used. The surface roughness parameters (S a , S q , S sk , S ku , S pk , S k and S vk) were identified by an optical interferometric profiler. Microstructural observations and crystallographic analysis were performed using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectroscopy (EDX) device for elemental analysis and an X-ray diffractometer (XRD), respectively. The Martens Hardness (HM), Indentation Modulus (E IT), elastic index (η IT) and Vickers hardness (HV) of all specimens were determined by instrumented indentation testing (IIT). The results were analyzed by one-way ANOVA and Tukey multiple-comparison tests (a=0.05). EDX and XRD showed the abutment screws to be mixed α- and β-phase titanium alloys. Microstructural analysis revealed a fine homogeneous microstructure without porosity, consisting of fine dispersoid rods of β-phase embedded in a continuous α-phase matrix. Statistically significant differences were found among the mechanical properies and surface roughness parameters apart from S q , S pk and S vk. The tested abutment screws showed significant differences in the probed properties, and, thus, differences in their clinical behaviour are anticipated. [ABSTRACT FROM AUTHOR]

The rapid setting rate restricts the application of sulfoaluminate cement (SAC), it is necessary to develop SAC mortar with a controlled setting time. Therefore, this paper tries to use sodium gluconate (SG) and mineral admixture to reduce its reaction speed and study the effects of SG and mineral admixture on the workability, mechanical properties and durability of SAC mortar. First, the optimal amount of SG doping was determined to be 0.4% under the comprehensive consideration of the working performance, mechanical performance, and durability of SAC. Again, based on the determination of SG dosing, the effects of four mineral admixtures, fly ash, silica fume, Ground Granulated Blast furnace Slag (GGBS), and limestone powder, on the mechanical properties and chloride ion penetration resistance of SAC were studied, and the optimal dosing of each mineral admixture was determined. Finally, a microscopic analysis of the specimen was conducted through a Scanning Electron Microscope (SEM) to reveal the reaction mechanism of SAC from a macroscopic perspective. [ABSTRACT FROM AUTHOR]

As a high-performance composite material, polyvinyl alcohol (PVA) fiber-reinforced engineered cementitious composites (PVA-ECCs) are often used in sub-elevated temperature environments (< 200°C) for long-term service. However, the effect of exposure time in sub-elevated temperature on the performance of PVA-ECCs is not still clear. In this study, the properties of PVA-ECCs in sub-elevated temperature environments were examined, with emphasis on the effect of exposure time (1, 3, 6, and 9 h). Furthermore, the microstructure and tensile behavior of single PVA fibers exposed to a sub-elevated temperature environment was investigated. Results showed that PVA-ECCs have enhanced tensile ductility at different sub-elevated temperature exposure times below 100°C. However, the tensile properties of PVA-ECCs at 150°C showed a strain retraction phenomenon at 6 and 9 h. The strain-hardening characteristics of PVA-ECCs gradually disappeared with the increase of the sub-elevated temperature exposure time at 200°C. The results of thermogravimetric-differential scanning calorimetry (TG-DSC), Fourier transformation infrared spectroscopy (FTIR), and scanning electron microscope (SEM) revealed that the degradation of PVA fibers was accelerated by exposure time in sub-elevated temperature, which caused the reduction of mechanical properties of PVA-ECCs. [ABSTRACT FROM AUTHOR]

Graphene nanoplatelets (GNP) are just one of the attractive graphene-based nanomaterials that are rapidly emerging and have sparked the interest of many industries. These small stacks of platelet-shaped graphene sheets have a unique size and morphology that quickly disperse into other materials such as polymers, resulting in higher-value composite materials with improved thermal, conductivity, and mechanical capabilities. A detailed analysis of reinforced High-Density Polyethylene (HDPE) using different sizes (2, 15, 25 μm) and compositions (8, 10, 15 wt.%) of Graphene Nanoplatelets (GNP) has been conducted. The microstructure of the HDPE/GNP nanocomposites was extensively examined during the melt blending and injection moulding processes. Based on the results, the nanocomposites with different sizes of GNP exhibited dissimilar behaviour with different compositions. Furthermore, scanning electron microscope (SEM) results indicated a homogeneous dispersion for GNP in melt mixing. Moreover, thermogravimetric (TG) data demonstrate that increasing filler showed a slight increase in the material's thermal stability. The use of GNP improved mechanical properties, as evidenced by the increases in Young's modulus of yield strength from around 100 MPa to over 400 MPa. This study provides a practical reference for the industrial preparation of polymer-based graphene nanocomposites. [ABSTRACT FROM AUTHOR]

In this article, maleic anhydride (MA) was used to graft-modify chitosan (CS) to obtain maleic anhydride-modified chitosan (MCS). Composite films with different ratios were prepared by melt blending-extrusion pelletizing-blown film using Poly (butylene adipate-co-terephthalate) (PBAT) as the substrate and CS or MCS as the filler. These films can be utilized in a variety of ways, such as food packaging, agricultural mulching film, and more. The composite films were characterized and tested by a Fourier transform infrared (FTIR) spectrometer, thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), scanning electron microscope (SEM), and electronic universal testing machine, and the effects of different fillers and filler contents on the properties of the composite films were investigated. The results showed that the thermal stability of the composite films decreased slightly with the increase in filler ratio, the melt crystallization temperature increased and then decreased, and the tensile strength and elongation at break of the composite films decreased. Compared with unmodified CS, MCS had better dispersion and compatibility when blended with PBAT, and the interaction between MCS and PBAT was greater than that of CS. The optimal filler amount of MCS was 6% for the combination of film material cost and performance considerations. [ABSTRACT FROM AUTHOR]

Polyetheretherketone (PEEK) is the leading high-performance thermoplastic biomaterial that can be processed through material extrusion (ME) additive manufacturing (AM), also known as three-dimensional (3D) printing, for patient-specific load-bearing implant manufacture. Considering the importance of cyclic loading for load-bearing implant design, this work addresses the high-cycle fatigue behaviour of 3D-printed PEEK. In this work, printed PEEK specimens are cyclically loaded under stress-controlled tension–tension using different stress levels between 75% and 95% of printed PEEK's tensile strength. The experimental results are used to document 3D-printed PEEK's fatigue behaviour using Basquin's power law, which was compared with previous fatigue research on bulk PEEK and other 3D-printing materials. As a pioneering study on its fatigue behaviour, the results from this work show that 3D-printed PEEK exhibits an above-average fatigue strength of 65 MPa, corresponding to about 75% of its tensile strength. Fracture surface analysis suggests that a transition can occur from ductile to brittle fracture with maximum stresses between 85% and 95% of the tensile strength. Evidence of crack propagation features on fracture surfaces under scanning electron microscope (SEM) observation suggests crack initiation in void defects created by printing deposition that propagates longitudinally through line bonding interfaces along layers. Considering this, 3D-printed PEEK's fatigue behaviour can be strongly related to printing conditions. Further research on the fatigue behaviour of 3D-printed PEEK is necessary to support its use in load-bearing implant applications. [ABSTRACT FROM AUTHOR]

This research investigates the combined effect of steel and natural fibre on the mechanical properties and spalling resistance of ultra-high performance concrete (UHPC) before and after exposure to elevated temperatures. The effects of two parameters, namely temperature (ambient temperature, 200 °C, 400 °C and 600 °C) and fibre type (solely macro end hooked steel fibre (MHS) and hybrid of micro straight steel fibre (MSS), macro end hooked steel (MHS) fibre and micro jute (MJ) fibre) on the mechanical properties, spalling resistance and mass loss of UHPC were studied. Micrographs from scanning electron microscope (SEM) test were utilized to appraise the steel fibre and jute fibre before and after exposure to elevated temperatures. The test results exhibited that the residual tensile strength and flexural strength were significantly declined after exposure to high temperatures for UHPC specimens reinforced with macro steel fibre only. Moreover, explosive thermal spalling occurred for this group of specimens under 600 °C. Whereas the combined use of jute fibre and micro-macro steel fibre was an effective approach to prevent the explosive thermal spalling under 600 °C and improve the residual tensile strength, flexural strength and toughness of UHPC. Furthermore, preliminary empirical expressions have been developed in this study to predict the residual mechanical properties of UHPC as a function of natural fibre content, steel fibre content and temperature. [ABSTRACT FROM AUTHOR]

During the extraction of geothermal heat, the changes in temperature and pressure environments can alter the mechanical and hydraulic behavior of fractured rock masses, affecting the overall transmissivity and heat extraction efficiency accordingly. This study carried out a series of experiments, including X-ray diffraction (XRD), scanning electron microscope (SEM), uniaxial compression tests, and surface morphological scanning, to explore the influence of reservoir temperature on the mechanical behavior of granite and fracture surface topography. The results indicate that as the temperature increases, the uniaxial compressive strength, elastic modulus, and Poisson's ratio of granite show similar variation patterns that increase as the temperature approaches 200 °C and then decrease. In addition, with the increase in temperature, the overall surface elevation and roughness parameters generally decrease due to surface asperity degradation, with the maximum mean mechanical aperture found at 200 °C. Flow simulations were conducted to further explore the influence of temperature and pressure environments on fracture transmissivity and flow fields. It is found that the normalized equivalent hydraulic aperture B N of the tested fractures decreases progressively as the stress increases, and more scattered distributions of B N are observed under higher compressive stresses. Moreover, with the continuous increase in temperature, the average B N slowly increases to its peak of ~0.78 at 200 °C, then it decreases to ~0.76 at 300 °C and remains nearly constant. These findings can be important for assessing heat production performances during the geothermal extraction process with spatially and temporally varying reservoir temperatures and pressures. • Temperature and pressure effect on granite properties are analyzed. • Surface roughness decreases due to heat-induced asperity degradation. • UCS and transmissivity reach their maximum at 200 °C with increasing temperature. [ABSTRACT FROM AUTHOR]

For the present investigation, Tungsten heavy alloys (WHAs), (90-x)W-6Ni-4Cu-xLa 2 O 3 are synthesized using the powder metallurgy route by liquid phase sintering at 1400 °C for 1 h in hydrogen atmosphere. The effect of variation of La 2 O 3 (Lanthanum oxide) dispersion in W-Ni-Cu alloy (0, 0.1, 0.5, 1.0, 1.5, and 2.0 wt%) on microstructural evolution was investigated using a scanning electron microscope (SEM) and transmission electron microscopy (TEM). The distribution of the tungsten, matrix, and La 2 O 3 were analyzed using X-ray energy dispersive spectroscopy (EDS). The influence of La 2 O 3 content on the densification behavior was also determined. The stereological quantifications were done on particle size and contiguity. The lowest W particle size was observed in sample of 2.0 wt% La 2 O 3 added WHA. However, this sample was found to have more porosity. The W particle size was reduced by about 30% with 2.0 wt% addition of La 2 O 3. The maximum value of bulk hardness of about 320 HV 5 was observed in 1.0 wt% La 2 O 3 content WHA. The three-point bend test was performed to determine the bending behavior of these alloys. The alloy with 1.0 wt% La 2 O 3 showed the maximum compressive strength of 1481 MPa and bending strength of 1021 MPa. Fractography revealed W-W interface de-cohesion fracture mechanism to operate pre-dominantly. W particle cleavage fracture mode was observed to increase with the addition of La 2 O 3 up to 1.0 wt% in the WHAs. • W-Ni-Cu alloys with La 2 O 3 processed via powder metallurgy LPS at 1400 °C. • With 2.0 wt% La 2 O 3 in W-Ni-Cu alloy reduces W particle size by 30 %. • The addition of 1.0 wt% La 2 O 3 turns out to give the best mechanical property. • Quantification of operational fracture modes attempted. [ABSTRACT FROM AUTHOR]

Magnesium oxychloride cement (MOC) as a green cement has superior mechanical properties such as high strength and quick gain of early strength, however the inherent brittleness has limited its applications where ductility is crucial. To enhance the strength and ductility, a novel hybrid fibre-reinforced MOC-based composite (FRMOC) is developed for the first time using polyethylene (PE) fibres and basalt fibres (BF) to reinforce the MOC. A systematic investigation of the effect of fibre dosage on the flowability, rheological properties, compressive strength, and tensile properties of the developed FRMOC is conducted in this study. The results revealed that the addition of fibre reduces flowability while increasing the yield stress and plastic viscosity. The 1-day compressive strength of the FRMOC reached 68.2–85.4% of the corresponding value at 28 days, demonstrating its high early strength characteristic. The mix with 1.25% PE and 0.75% BF exhibited the maximum compressive strength at all curing ages. All the mixes consistently demonstrated excellent tensile strength and tensile strain capability (ductility), with the tensile strength and tensile strain capacity of 10.95 MPa and 4.41% achieved for the mix of 2% PE fibre, and 8.49 MPa and 2.43% for the mix of 1.25% PE and 0.75% BF respectively. Moreover, a decline in strength characteristics and strain capacity was observed as BF percentages increased. Scanning electron microscope (SEM) analysis was further employed to investigate the morphological changes in the FRMOC matrix at the microscale to discover the fibre reinforcing mechanism. • Hybrid fibre reinforced MOC (FRMOC) with enhanced strength and ductility is developed. • FRMOC demonstrates high-early-strength characteristic. • Rheological, physical, and mechanical properties were evaluated. • 1.25% PE and 0.75% BF-reinforced FRMOC exhibited maximum tensile strength and strain capacity. • Microstructural analysis is performed to analyse the morphological alterations. [ABSTRACT FROM AUTHOR]

For facilitating carbon utilization and minimizing carbon emission, steel fiber was coated with polyethyleneimine and subjected to a moist condition to capture carbon dioxide, and the CO 2 captured steel fiber (CPSF) was formed, which was used to prepare ultra-high performance concrete (UHPC). After heat curing, compressive strength and splitting tensile strength of UHPC were determined. The results reveal that, compared to the UHPC with polyethyleneimine-coated steel fiber (PSF), the compressive strength and splitting tensile strength of UHPC with CPSF increased by 16.3% and 3.4%, respectively. The microstructural tests including environmental scanning electron microscope, X-ray diffraction and thermogravimetric analysis prove that, under a combined curing of 90 °C hot water and subsequent 200 °C dry-air heating, carbon dioxide chemically combined in the coating of CPSF can be released during the combined curing and react with calcium hydroxide or cement clinkers in the matrix surrounding CPSF to generate calcium carbonate and calcium-silicate-hydrate (C–S–H) gels, which is responsible for both the refinement of microstructure and enhancement of mechanical properties of UHPC. [ABSTRACT FROM AUTHOR]

Polylactide (PLA) represents one of the promising biodegradable polymers with great potential to replace petroleum-derived plastic. In the last decade, massive efforts have been devoted to overcoming the brittleness of PLA, expecting comparable mechanical properties to traditional polyolefin and polyester. Introducing oriented texture into PLA has recently been reported to be an effective approach to improve ductility without sacrificing their high strength. However, the understanding of the mechanism is absent. Herein, we study the fracture behaviors of anisotropic PLA with oriented lamellar crystal by employing operando synchrotron X-ray scattering and diffraction. It has been found that the cavities generated parallel with stress direction can restrain the fast failure of PLA. Nevertheless, the load-carrying ability of oriented PLA lamella is still limited. On this basis, we further introduce the flexible nanofibers into an oriented PLA matrix that enables crystals to effectively participate in the stress dissipation, resulting in significant enhancement of the ductility of PLA while maintaining their high strength. Combined with morphological study by scanning electron microscope, we propose a qualitative model to describe the detailed fracture behavior of PLA with oriented texture, which may provide a reliable theoretical guideline towards further optimization of the mechanical properties of PLA. [Display omitted] • Synchrotron X-ray techniques was used to study the fracture behaviors of PLA. • Cavity along orientation direction plays important role in fracture process. • A new way for enhancing the ductility of PLA while maintaining high strength. [ABSTRACT FROM AUTHOR]

The primary purpose of this work is to study the fabrication of a flexible natural cellulosic fiber composite. In this respect, natural cellulosic fiber was obtained by modified poplar wood fiber through sodium hydroxide (NaOH) and γ-Aminopropyl Triethoxysilan. Then, the composites were fabricated by hot-pressing the modified wood fibers and polyurethane following characterization. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) observation results confirmed that some of the hemicellulose and lignin were removed from wood fibers after NaOH modification and successfully grafted with alkoxy structures after KH550 modification. NaOH&KH550 modification improved the interfacial compatibility between poplar wood fibers and polyurethane. The flexibility of the composites was improved (the slenderness value was reduced by 113 %), allowing flexible deformations such as bending, twisting, and knotting. In addition, thermal stability, tensile strength (increased by 105 %), elongation at the break (increased by 125 %), and water resistance were increased. This flexible natural cellulosic fiber composite is expected to be applied in the veneering of curved materials and special-shaped structure furniture, providing a theoretical basis for improving the added value of wood-based composites. [ABSTRACT FROM AUTHOR]

As an environmentally friendly material, alkali-activated fly ash-slag (AAFS) is considered as a promising alternative cement because of its excellent mechanical properties and thermal stability. Nevertheless, high temperature induced damage in AAFS can potentially bring serious risks for its practical applications. This paper presents a systematic experimental study on behaviour of AAFS paste subjected to elevated temperatures up to 800 °C in terms of microstructure as well as thermal and mechanical properties. Microstructural evolution was characterised by means of Rietveld-based quantitative X-ray diffraction (QXRD), backscattered scanning electron microscope (BSEM) and X-ray microcomputed tomography (XCT), while thermal and mechanical properties were evaluated from thermogravimetric analysis (TGA), thermal deformation and compressive and flexural strengths. Results indicate that the compressive strength of AAFS paste rises by 77.5 % at 200 °C, followed by a mitigation from 200 to 600 °C and a regain at 800 °C. Different phases in AAFS paste including unreacted particles, reaction products and pores took up 30 %, 67.7 % and 2.31 % at ambient temperature, and 4.95 %, 84.8 % and 10.3 % after exposure to 800 °C, respectively, suggesting the recrystallisation with the formation of nepheline and gehlenite. In addition, the relationships between microstructural characteristics including three-dimensional (3D) pore structure features and thermal and mechanical properties of AAFS paste at elevated temperatures were explored and discussed in depth to gain insights into the underlying degradation mechanisms including pore pressure build-up, thermal gradient and phase transformation. [ABSTRACT FROM AUTHOR]

Melia dubia is a rapidly expanding tree species in southern India, but its main drawback has been limited use in wood-based panel products until recently. To address this research gap, this study aimed to develop three reinforcement materials for producing Reinforced Laminated Veneer Lumber (RLVL) using Melia dubia. Three types of reinforcement materials, chopped glass fiber mat (CGM), glass fiber mesh (GM), and bamboo mat (BM) were employed in two layers to manufacture RLVL. The investigated parameters included physical, mechanical, and bonding performance. Furthermore, morphological images were analyzed using optical and scanning electron microscopes. The research findings revealed that the highest performance was demonstrated by BM, followed by GM and CGM. These results suggest that all three reinforcements enhanced the mechanical properties and overall performance of RLVL. Arranging the reinforcement layers closer to the surface veneer layer in the assembly resulted in outstanding mechanical properties for RLVL. The performance is superior to solid wood made from the same wood species. The findings indicate that RLVL demonstrated superior mechanical properties to laminated veneer lumber (LVL) and solid wood. The modulus of rupture for LVL reinforced with CGM, GM and BM was 7.27%, 30.91%, and 32.73% greater respectively, than that of unreinforced LVL. The composite LVL reinforced with bamboo and glass matting exhibits potential for successful utilization in outdoor structural applications, including beams, rafters, and purlins. • LVL reinforced with CGM, GM, and BM exhibited excellent modulus of rupture. • RLVL demonstrated superior mechanical properties to LVL and solid wood. • LVL reinforced with GM and BM can successfully utilized in outdoor structural applications. [ABSTRACT FROM AUTHOR]

To obtain a robust diffusion-bonded joint at a relatively low temperature, Nb foil was applied as an interlayer to the diffusion bonding of Zr-4 alloy, and a wide process parameter involving the bonding temperature of 720–820 °C and holding time of 30–120 min was investigated to reveal the evolution of interfacial structure and mechanical properties of the joints. The β-(Zr, Nb) and Widmanstädter microstructure formed at the interface induced by the eutectoid transformation of the diffused Zr and Nb at the bonding temperatures over 740 °C. The phase structure and the thickness of β-(Zr, Nb) layer were not considerably influenced by the increase in diffusion parameters while the Widmanstädter zone thickened significantly. Moreover, the tensile strength and elongation of the resultant joints could be stabilized above 433 MPa and 7.8%, respectively, when the bonding temperature exceeded 760 °C with a holding time of 30 min. By extending the holding time to 60 min at 760 °C, the tensile strength and elongation could reach 454 MPa and 12.6%, respectively, comparable to those obtained at an elevated temperature of 820 °C for 30 min. Additionally, the samples fractured at the diffusion layer were characterized by the in-situ tensile test under the scanning electron microscope, and it was discovered that the crack initiation and propagation process occurred mainly between the β-(Zr, Nb) and Widmanstädter diffusion zone. • The well-bonded Zr-4 joints were achieved by the application of Nb interlayer. • The diffusion layer consisted of β-(Zr, Nb) and Widmanstädter microstructure. • The Nb addition lowered bonding temperature without weakening tensile properties. • The fracture occurred between the β-(Zr, Nb) and Widmanstädter diffusion zone. [ABSTRACT FROM AUTHOR]

To improve the low-temperature toughness of epoxy resins, in this study, an epoxy-terminated hyperbranched polysiloxane (EPTS-12) was synthesized and introduced into the epoxy resin as a toughener. The structure of EPTS-12 was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1H NMR), and the fractured surfaces of the modified resins were observed by a scanning electron microscope (SEM). With the content of EPTS-12 at 5 wt%, under room temperature (RT) and − 72 °C, the maximum values of elongation at break were 14.19% and 16.06%, increasing by 35.66% and 74.19% respectively. The test results of dynamic mechanical analysis (DMA) also showed that the toughness of the modified epoxy resins was improved. The SEM images of the fractured surfaces of the modified resins were used to investigate the toughening mechanism of the toughener (EPTS-12). With the virtue of a simple synthesis process, low cost, and good reproducibility, this toughener can further expand the application of epoxy resins. [Display omitted] • With 5phr EPTS-12, under RT and − 72 °C, the elongation values were increased by 35.66% and 74.19% respectively. • The dynamic thermomechanical behaviors of the composites were investigated via dynamic mechanical analysis (DMA). • The working mechanism of the toughener was studied by SEM images of the fractured surfaces. • These research results can provide a reference for the design and development of epoxy tougheners. [ABSTRACT FROM AUTHOR]

The surface topography and interface characteristics play a significant role in determining the mechanical properties of carbon fiber reinforced polymer (CFRP) composites. These features are primarily influenced by the surface chemical structures and their interactions with the matrix resin. Here, we developed a rigid-flexible coating consisting of polyetheramine (PEA) and polydopamine (PDA) on the fiber surface to control the interface and improve the mechanical properties of CFRPs. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectrum (FT-IR) results validated the successful introduction of polymeric chains and fiber surface characteristics including rough surfaces, slim polymer layers and uniform dots were examined by scanning electron microscope (SEM) and transmission electron microscopy (TEM). Contact angle tests indicate that the functionalized coating noticeably enhances the interaction force between carbon fibers, promoting improved wettability by the matrix resin. The bending and interlaminar shear strength of CFRP prepared by functional carbon fiber are increased by 45.76 % and 47.63 %, respectively. The drop weight impact (DWI) test confirms the positive effect of improved interfacial properties on the out-of-plane impact resistance of CFRPs. [Display omitted] [ABSTRACT FROM AUTHOR]

The current investigation aims to choose an alternate potential replacement for the nonbiodegradable synthetic fibers used in polymer composites. This goal motivated the thorough characterization of Rosa hybrida bark (RHB) fibers. The research explored fiber characterization such as morphological, mechanical, thermal, and physical properties. The suggested fiber features a percentage of cellulose, hemicellulose molecules, and lignin of 52.99 wt%, 18.49 wt%, and 17.34 wt%, respectively according to chemical composition studies, which improves its mechanical properties. It is suitable for lightweight applications due to its decreased density (1.194 gcm−3). The purpose of the Fourier transform infrared spectroscope was to observe and record how various chemical groups were distributed throughout the surface of the fiber. The presence of 1.41 nm-sized crystalline cellulose and further XRD analysis showed a crystallinity index of 75.48 %. Scanning electron microscope studies revealed that RHB fibers have a rough surface. According to a single fiber tensile test, for gauge length (GL) 40 mm, Young's modulus and tensile strength of RHB fibers were 6.57 GPa and 352.01 MPa, respectively, and for GL 50 mm, 9.02 GPa and 311 MPa, respectively. Furthermore, thermo-gravimetric examination revealed that the isolated fibers were thermally stable up to 290 °C and the kinetic activation energy was found to be 75.32 kJ/mol. The fibers taken from the Rosa hybrida flower plants' bark exhibit qualities similar to those of currently used natural fibers, making them a highly promising replacement for synthetic fibers in polymer matrix composites. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the effect of using single and combined marble dust (MD), granite dust (GD) and nano alumina (NA) on the performance of Portland cement concrete. MD and GD were separately replaced by different percentages of cement (2, 4, 6, 8 and 10 wt%). Furthermore, NA was used as addition by different percentages (0.25, 0.5, 0.75, 1.0 and 1.25 wt%) in the individual mixtures. The optimal ratios for MD, GD and NA were used to design two concrete mixtures with combined 6%MD+ 1%NA and 6%GD+ 1%NA. The physical properties (consistency, initial and final setting times), the workability (slump cone test), the mechanical properties (compressive, splitting tensile and flexural strengths) and microstructure analysis (X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Energy-Dispersive X-ray (EDX)) were carried on the single and combined mixtures in addition to control mix. Results revealed a rise in the water quantity needed to achieve standard consistency, along with a reduction in both initial and final setting times, as the content of GD and NA increased. However, in comparison to the control mix, minor effects in the consistency or the setting times was observed when various MD contents were used. Regarding workability, its consistently decreased in all cases in correlation with the surface area of the materials utilized. The highest reduction was observed when employing NA, characterized by the largest surface area, followed by GD, and then MD, which had a marginal effect on workability. For hardened concrete, there was an improvement in strengths of samples with replacing individually MD and GD content up to 6% at all curing ages, followed by a decrease in strengths when the content reached 10% of cement replacement compared to control sample. Concrete mixtures with addition of NA showed significant improvement in strengths at all percentages of addition until reached the maximum increase in strength at 1% then slightly decreased. Concrete with combined (6%MD+1%NA) and (6%GD+1%NA) show significantly improved mechanical properties and compact microstructure enriched with C-S-H in comparison to concrete samples using 6%MD, 6%GD and 1%NA separately. • The water of consistency increased while the initial and final setting times were shortened. • The workability of concrete was significantly diminished by NA particles. • An improvement in strength was recorded for the combined use of 6% MD and 1% NA. • An enhancement of flexural and tensile strength was attributed to the individual use of MD, GD, and NA additives. • The results of EDX analysis confirmed that lower Ca/Si ratio led to higher mechanical properties. [ABSTRACT FROM AUTHOR]