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A polyol bonding agent (BA) was utilized to enhance the mechanical properties of propellant with low aluminum content. Through scanning electron microscope (SEM) and X‐ray photoelectron spectroscopy (XPS) analysis, it was discovered that BA can physically bond to the surfaces of ammonium perchlorate (AP) and hexogen (RDX). The results of mechanical testing showed that the use of BA can significantly improve the mechanical properties of propellants. Specifically, as the amount of BA increases, the maximum tensile strength (σm) of the propellant also increases, the fracture elongation (εb) initially increases and then decreases, the "dewetting ratio" continuously decreases, and the creep resistance of the propellant also increases. At a BA content of 0.2%, the σm of the propellant reaches 0.6 MPa, the εb exceeds 50%, and the "dewetting ratio" is less than 1.1. [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]

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]

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]

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]

To enhance the fracture toughness of epoxy resin at low temperature, a secondary branched epoxy‐terminated silicone resin (ESR‐6) was synthesized and incorporated into bisphenol A epoxy resin at different contents. The structure of ESR‐6 was characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance (1H NMR), and the fracture surface of the composites was observed by scanning electron microscope (SEM) and atomic force microscopy. At room temperature and − 70°C, the maximum values of elongation at break were 15.78% and 12.55% with 10 wt% ESR. Compared with those of neat epoxy resin, the values of elongation at break of the composite were increased by 50.86% and 36.12%. The results of dynamic mechanical analysis also showed that the toughness of the modified resin had been improved. The SEM images of the fracture surfaces suggested that the fracture mode of the modified resin changed from brittle one to plastic one because of the addition of ESR‐6, which further confirmed the toughening effect of ESR‐6. These research results may provide a new strategy for enhancing the low‐temperature toughness of epoxy resins. [ABSTRACT FROM AUTHOR]

The present study focuses on how microalgae protein biomass, such as spirulina (SP), can be used to create thermoplastic blends and algal‐based bioplastics. Algal bioplastics can be customized for a variety of material properties and applications while remaining biodegradable. In this work, the casting approach has been performed to create spirulina‐starch‐glycerol composite films by adding SP to plasticized starch films. The characteristics and properties of the composite films were inspected by Fourier transform infrared (FTIR), scanning electron microscope (SEM), tensile strength, antimicrobial activity, and biodegradation analysis. The composite film with 3% SP was found to have the best combination of mechanical and chemical properties, and additional SP causes the mechanical properties to degrade. The results demonstrated that bio‐composites prepared by plasticized starch and containing SP could be promising in the development of new environmentally friendly bio‐nanocomposites for interesting applications in food packaging. [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]

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]

In this work, this study aimed to overcome the inherent disadvantage of low thermal stability and brittleness of epoxy resins. A novel modifiers containing alkynyl‐ and allyla‐ groups, (E)‐1‐(4‐(allyloxy)‐3‐methoxyphenyl)‐N‐(3‐ethynylphenyl)methanimine (MNEM) was prepared and confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H‐nuclear magnetic resonance (1H NMR), and selected to improve the thermal stability and toughness of bisphenol A‐type epoxy resin (E51). The blend resins were produced by blending with different contents of MNEM into E51 resin, named E‐MNEM resins. Meanwhile, the thermal stability, mechanical properties, and micromorphology of E‐MNEM blends were analyzed in details. It was found that the thermal stability of E‐MNEM resins was improved by increasing the proportion of MNEM. Compared with E‐0MNEM resin, when the MNEM concentration reached 40 wt%, the char yield (Yc) increased from 14.95 to 29.62%, reflecting a 98.1% improvement. In addition, an appropriate concentration of MNEM could be conductive to improving the mechanical properties. An improvement of 25.5 and 7.1% in elongation and tensile strength along with the maximum value of 17.6 kJ/m2 for the impact strength was achieved by the cured E‐MNEM resins containing 20 wt% of MNEM. Finally, the fracture surface morphology of the E‐MNEM resins was analyzed by the scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

Three types of layered‐hybrid lattice structures (LHLSs) with different layer thicknesses composed of body‐centered‐cubic (BCC) and face‐centered‐cubic (FCC) unit cells are designed and manufactured by selective laser melting using Ti–6Al–4V powder. The microstructure and surface morphologies of the three types of the selective laser melting‐formed LHLSs are examined by an optical microscope and scanning electron microscope (SEM), respectively. Quasistatic compression experiments are carried out to investigate the mechanical properties. The results show that the layer thickness has a significant effect on the mechanical properties and deformation behaviors. The elastic modulus, yield strength, and ultimate compressive strength of LHLS increase with the increasing BCC and FCC layer thickness, respectively. Based on the observations of deformation process, a 45° shear band and axial fracture are observed in LHLS‐8, and step‐like deformation bands are observed in both LHLS‐4 and LHLS‐2 samples. Besides, the influence of different loading directions on mechanical properties is also investigated; it is found that the ultimate compressive strength loaded in the transverse direction is independent of the layer thickness in LHLSs. [ABSTRACT FROM AUTHOR]

Cyanate ester (CE) resins possess excellent thermal and mechanical characteristics, yet their brittleness and high cross‐link density limit their practical application. To overcome this limitation, the modification of CE with thermoplastic resins has been employed as an effective strategy to enhance their toughness and mechanical properties. In this study, a novel fluorinated poly(aryl ether nitrile) (PFPEN) with excellent solubility and thermal properties was synthesized through a nucleophilic substitution reaction. The effect of the addition of PFPEN on a blend composed of bisphenol A cyanate ester (ACE) and a mixed catalyst was investigated. Differential scanning calorimetry results showed that the addition of PFPEN facilitated the curing reaction of ACE, resulting in a lower exothermic peak temperature. Compared to the pure ACE, the addition of PFPEN at 20 phr significantly improved the tensile and impact strengths of the resin, as well as enhanced the lap shear strength at room temperature by 36% and the peel strength by 320%, respectively. The scanning electron microscope results showed a ductile fracture mechanism. However, it should be noted that the decrease in crosslinking density resulting from the addition of PFPEN may affect the lap shear strength at 300°C and the glass transition temperature (Tg) of the material. [ABSTRACT FROM AUTHOR]

This research aims to study the effect of injection parameters on the mechanical properties of the developed green composites. Natural flax fibre and biodegradable polymer, polylactic acid was chosen to develop the green composites. The flax fibre was chemically treated using sodium hydroxide to fabricate the green composite by injection moulding. The injection parameters namely (i) injection pressure (bar), (ii) injection speed (mm/s), and (iii) injection temperature (°C) was considered to investigate their effect on the mechanical properties of developed polylactic acid/flax green composites. The mechanical properties, such as (a) tensile strength (TS), (b) tensile modulus (TM), (c) percentage elongation under tensile loading (PET), (d) flexural strength (FS), (e) flexural modulus (FM), (f) percentage elongation under flexural loading (PEF), (g) compressive strength (CS), and (h) shear strength (SS) was evaluated under different injection conditions. Furthermore, the morphology of the mechanically tested specimens was investigated using a scanning electron microscope. Grey relational analysis was performed to find the optimal injection condition. The optimum injection condition depicting superior mechanical properties was found at injection parameters combination of 90 bar (injection pressure), 60 mm/s (injection speed), and 165 °C (injection temperature). [ABSTRACT FROM AUTHOR]

The microstructure and properties of an AlSi10Mg alloy produced by selective laser melting were examined using optical microscopes, scanning electron microscopes, electron backscattered diffraction, and x‐ray diffraction. The results show that the mechanical characteristics of selective laser melting formed AlSi10Mg alloy is superior to those of traditional sand cast AlSi10Mg alloy due to fine grain strengthening and solid solution strengthening. AlSi10Mg alloy formed by selective laser melting is mainly composed of α‐aluminum solid solution, eutectic silicon with network structure and a small amount of Magnesium silicon precipitated phase, and different cross‐sections have unique microstructures and properties. The XOY plane is composed primarily of equiaxed grains with an average grain size of 7.34 μm and a {001} <100> cubic texture, and it has a hardness value of 130.7 HV 0.2. The majority of the YOZ plane, which has a {111}<110> brass R texture and a hardness value of 108.9 HV 0.2, comprises columnar crystals with an average grain size of 8.42 μm. [ABSTRACT FROM AUTHOR]

In this study, we investigated how the chemical structural properties, mechanical properties, and morphology of large‐size graphene platelets (LGPs) doped glass fabric (GF)/epoxy composites are affected by varying loading amounts of LGPs. Scanning electron microscope results revealed that the dispersion and filling effect of LGPs can improve the flowability of the resin, reducing the aggregation and shrinkage of the resin on the glass fabric surface, thereby facilitating better resin infiltration and coverage of the glass fabric surface. From the spectrum analysis, the binding of LGPs with epoxy resin was the physical combination, without new chemical groups generated during the curing process. The addition of LGPs improved the ratio of the crystalline phases in the composites, from 30.00% of the GF/epoxy to 57.50% of the GF/epoxy@2.2LGPs. Mechanical properties indicated that the composites exhibited greater tensile strength than pure GF, which progressively increased with increasing LGPs content until it reached 1.5 wt%, then the tensile strength starts to decrease. And the GF/epoxy@1.5 LGPs exhibited 136% enhancement in tensile strength compared to other carbon fillers reinforced composites, which achieved a satisfactory enhancement under relatively low loading content. Highlights: The effect of the large‐size graphene platelets (LGPs) on the properties of glass fabric (GF)/epoxy composites.Compared to the glass fabric/epoxy composite, the LGPs doped composite possessed a much higher storage modulus (E′).The LGPs doped composite exhibited 136% enhancement in tensile strength compared to other carbon fillers reinforced composites.The addition of LGPs improved the ratio of the crystalline phases in the composites. [ABSTRACT FROM AUTHOR]

In recent decades, considering environmental issues, partial replacement of Portland cement with supplementary cementitious material (SCM), namely ground granulated blast furnace slag (GGBS), has been in the spotlight of research. On the other hand, carbon‐based nanomaterials, especially graphene oxide (GO), are recognized as an extraordinary additive with special characteristics that can be included in cementitious materials. In this research, the impact of GGBS on the mechanical properties and durability of GO‐modified mortars was investigated at 28 and 90 days. The results demonstrate that by increasing the content of GGBS, a decrease in the flexural and compressive strength compared to plain cement sample was seen. On the other hand, incorporation of GGBS and GO led to higher strength compared to GO‐cement mortar. Also, the compressive strength of the sample containing 20% GGBS and 0.03% GO was 38.7% higher than the plain cement sample at 90 days. On the other hand, adding GGBS to a GO‐reinforced sample resulted in a more durable specimen against chloride and acid environments. The sample made of 40% GGBS in GO‐modified mortar not only has the best efficiency in harsh environments but also has the lowest water absorption. This mortar improved the migration coefficient, mass loss in HCl solution, and initial sorptivity by 20.1%, 57.7%, and 37.1%, respectively. Moreover, the mentioned sample had a denser microstructure with smaller cracks compared to other samples, based on scanning electron microscope (SEM) images. [ABSTRACT FROM AUTHOR]

Addition of copper oxide nanoparticles (CuONPs) to poly (butylene‐adipate‐co‐terephthalate) (PBAT)/thermoplastic starch (TPS) biopolymer blend produced bionanocomposite films with improved mechanical and oxygen barrier properties, as well as enhanced other benefits including antimicrobial activity. In this study, the PBAT/TPS‐CuO bionanocomposite films with varying CuONPs contents (0.05%, 0.5%, 1%, and 2%) were challenged by food simulants (10% ethanol represented to aqueous food and 3% acetic acid represented to acidic food) in accordance with European Regulation 10/2011. CuONPs in the bionanocomposite films demonstrated good stability when exposed to 10% ethanol; however, it was dissolved in 3% acetic acid. The X‐ray diffraction and the energy dispersive spectroscopy results showed that CuONPs in the film were completely lost after acid exposure, whereas CuONPs in the films exposed to 10% EtOH were preserved. The maximum overall migration value was 5.0 mg/dm2. Inductively coupled plasma optical emission spectroscopy was used to confirm the presence of Cu in the simulants. The highest soluble Cu value of 12.39 mg/kg was detected from PBAT/TPS‐CuO2%, while migration value decreased as concentration ratio in film decreased. Although both values were within the threshold limits established by current legislation for non‐specific migration limit substances in food contact materials, the properties of bionanocomposite were altered. The mechanical properties of a post‐migrated PBAT‐TPS/CuO films taken from acidic conditions were reduced by 22% in tensile strength and 53% in elongation at break due to holes and microcracks on the film surface observed by scanning electron microscope. The average sealing strength of all bionanocomposite films decreased by about 25% after acid exposure. The oxygen permeability, on the other hand, was significantly improved, with a 16.3% reduction. Because the film had lost all of its active agent, film was unable to inhibit Escherichia coli growth. While 3% acetic acid caused dissolution of CuONPs and significant changes in properties of PBAT/TPS‐CuO film, 10% ethanol caused very minor to no changes in bionanocomposite film properties. [ABSTRACT FROM AUTHOR]

Spark plasma sintering (SPS) is a new sintering method having shorter sintering time and higher densification speed than the traditional sintering methods. In this paper, the Si3N4/TiC ceramic tool material is sintered by SPS. The microstructure and mechanical properties of the material under different sintering parameters are compared. The sintering process of the material is then analyzed, and the best sintering parameters are obtained. Heat the material to 1600°C and keep the temperature for 15 min, then continue to heat to 1700°C and keep the temperature for 10 min, Si3N4/TiC ceramic tool material has high mechanical properties, its bending strength, fracture toughness, and Vickers hardness are 959 MPa, 8.61 MPa·m1/2, and 15.21 GPa, respectively. The scanning electron microscope (SEM) analysis shows that under this condition, the sintering additives and Si3N4/TiC material form the liquid phase, which makes the Si3N4 particles rearrange, dissolve, precipitate, and transform into rod shape β‐Si3N4. In addition, under the action of pulse current and external pressure, electric sparks are generated between TiC particles, which allows the material transfer and particle refinement. Therefore, the β‐Si3N4 has uniform grain size, and it is vertically and horizontally arranged in the structure, which makes the material have excellent mechanical properties. [ABSTRACT FROM AUTHOR]

Due to the depletion of petro‐based sources and environmental consciousness, researchers are striving to replace synthetic fibers and resins in composites with bio‐sourced ones without compromising their properties. In this regard, the present study investigates the effect of partially replacing epoxy moieties with castor oil based bio‐resins on various properties of epoxy resin and its flax fiber reinforced composite system to achieve sustainable materials, thereby encouraging the bio‐based theme. Base‐catalyzed transesterification was used to synthesize epoxy methyl ricinoleate (EMR) as a low viscous reactive green monomer derived from epoxidized castor oil (ECO). The influence of both ECO and EMR bio‐resin on various mechanical, thermo‐mechanical properties, free mode vibration, and water absorption of epoxy and its composites were studied. The composition with 20% of ECO and EMR was optimized based on stiffness‐toughness balance. The inclusion of 20% EMR significantly escalated the tensile, impact, and fracture toughness properties of epoxy composites by 6.45%, 12.8%, and 14.2%, respectively. The strong fiber‐matrix interface was confirmed by increased pullout adhesion by 21% and 35.1% due to the addition of ECO and EMR, respectively. Dynamic mechanical analyzer revealed a 12% higher storage modulus for EMR modified composites than ECO counterparts. Scanning electron microscope morphology revealed superior interfacial adhesion between fiber and matrix in case of EMR modified bio‐composite, which resulted in a lower water diffusion coefficient than ECO modified bio‐composite. These results showed that the 20% EMR customized epoxy composite is dimensionally stable with improved mechanical properties and may act as a green alternative to petro‐sourced epoxy composites in automotive and semistructural applications. Highlights: Effects of castor oil based bio‐resins on epoxy composites are studied.Composites with significant bio‐content (~50 wt%) are developed.EMR modified epoxy composites exhibited improved mechanical properties.A strong fiber‐matrix interface was confirmed by increased pullout adhesion.Reduction in pot life of epoxy was observed on adding ECO and EMR. [ABSTRACT FROM AUTHOR]

In a nitrogen atmosphere, a novel composite, Poly(Acrylonitrile‐co‐Acrylamide)/crab shell powder, was synthesized by combining two monomers, acrylonitrile (AN) and acrylamide (Aam), with varying weight percentages of crab shell powder (CSP) as bio‐filler. The synthesized composite Poly (AN‐co‐Aam)/CSP, copolymer Poly (AN‐co‐Aam), and CSP were characterized using Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetric (TGA) analysis, derivative thermogravimetric (DTG) analysis, and a scanning electron microscope (SEM). The mechanical properties, like tensile, flexural, and impact strengths, were studied. The hardness, biodegradability, and water absorbency properties have been studied using appropriate methodologies. The SEM images and FTIR data confirm the appropriate synthesis of the composite material and the uniform distribution of CSP. The mechanical strength increases with the rise in concentration of CSP up to 20 wt. % and then gradually decreases. The thermal analysis reveals that the composite exhibits adequate thermal stability. The artificial neural network (ANN) model is used for the prediction of mechanical properties, which shows adequate results with the experimental results. The training and test datasets use a correlation factor associated with this analysis that is higher than 0.9, which confirms that the expected values of the mechanical performance are an excellent comparison to the experimental value. [ABSTRACT FROM AUTHOR]

In the present investigation, moringa oleifera and bamboo fibers extracted from Ethiopia are studied to understand their mechanical properties. Three types of woven composites namely moringa/epoxy, bamboo/epoxy and moringa/bamboo/epoxy (hybrid) are fabricated by maintaining 60 vol% fiber content. Additionally, neat epoxy samples are prepared for comparison. Tensile and flexural properties are investigated in terms of strength and modulus. Tensile test results depict brittle failure for all composites and infer increase in fracture strain of woven composites as compared with neat epoxy. Tensile modulus and strength of woven composites increase in the range of 19%–39% and 18%–281%, respectively as compared with neat ones. Flexural stress–strain profiles of neat epoxy, moringa/epoxy and moringa/bamboo/epoxy composites linear curves until failure indicating brittle mode while bamboo/epoxy composites shows non‐linear stress–strain profiles revealing non‐brittle mode of failure. Flexural properties exhibited by bamboo/epoxy and moringa/bamboo/epoxy reveal comparable properties to each other yet superior than moringa/epoxy and neat epoxy composites mainly attributed to the good bonding of constituents and compatibility. All the woven composites reveal an increase in flexural modulus and strength and are in the range of 31%–96% and 5.79%–51.12%, higher than the neat epoxy. Finally, fractured surfaces of specimens are analyzed using scanning electron microscope to understand the structure property correlations. [ABSTRACT FROM AUTHOR]

This study investigated the feasibility of using two types of waste glass sand as fine aggregate replacement in ambient cured alkali‐activated mortars (AAMs). Fly ash (FA) and ground granulated blast furnace slag were used as aluminosilicate source materials to produce the AAMs. The waste glass sand was used to replace 0%, 25%, 50%, 75%, and 100% fine aggregate (by mass) in AAMs. The influences of the use of waste glass sand, for the replacement of fine aggregate, on slump flow, setting time, compressive strength, and flexural strength of ambient cured AAMs were evaluated. It was found that the slump flow and setting time of ambient cured AAMs significantly increased as the percentage of replacement of fine aggregate by waste glass sand increased. However, the compressive and flexural strengths of ambient cured AAMs decreased when 50% and over fine aggregate were replaced by waste glass sand. The ambient cured AAMs with 25% replacement of fine aggregate with waste glass sand achieved the highest compressive and flexural strengths. Scanning electron microscope analysis indicated that the increase in the compressive strength and flexural strength of AAMs was due to the bridging‐like effect and filling effect provided by the waste glass sand. The use of waste glass sand as a partial replacement of fine aggregate in ambient cured AAMs was found to be feasible. In addition, 25% of the fine aggregate replaced by waste glass sand resulted in the best mechanical properties for ambient cured AAMs. [ABSTRACT FROM AUTHOR]

In this study, a novel biobased allyl compound with Schiff‐based structure (MPAM) was developed to improve the toughness and thermal properties of 4,4′‐bismaleimidodiphenylmethane (BDM). The chemical structure of MPAM was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR). A series of BDM/DBA‐MPAM blend resins (BD‐MPAM resins) were prepared by adjusting the mass ratio of BDM + DBA (BD) to MPAM. The effects of MPAM content on the curing behavior, thermal and mechanical properties of BD‐MPAM resins were discussed in details. Compared with BD resin, the thermal stability of modified resins was improved by increasing the content of MPAM. Meanwhile, an increase of 37.1% in flexural strength, and 228 MPa in flexural modulus were obtained for the cured BD‐MPAM resin having 10 wt% MPAM loading compared to the BD resin. The impact strength of BD‐10 wt% MPAM is of the maximum value (6.6 kJ/m2). Finally, the fracture surface morphology of the BD‐MPAM resins was studied by the scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

For commercial civil applications of laminated composite material, characterizations to forecast the interlaminar shear behavior and viscoelastic response across a wide temperature range are essential. In this study, the interlaminar shear strength (ILSS) of glass/epoxy (GE) composites dispersed with binary nanofillers nanosilica‐multilayer graphene (NS‐MLG) and nanosilica‐nanoclay (NS‐NC) was analyzed at an in‐situ testing temperature of 20, 70, and 110°C. Further, the viscoelastic property of the composites was studied using a dynamic mechanical thermal analyzer (DMTA) in the temperature range of 35–165°C. An increase in the ILSS value of around 9% and 10% was observed at room temperature for GE/MLG‐NS and GE/NC‐NS, respectively, compared to control GE composites. In contrast, the trend was seen to change at higher temperatures. There was a slight decrement in the storage modulus (E′) of GE/MLG‐NS and GE/NC‐NS composites in the glassy region compared to control GE composites. The mean Tg of the GE composite (control) was nearly 107.3°C when the E′ decline onset temperature was taken into account, but after the addition of MLG‐NS, it was 10.1°C below. The mean Tg of GE/NC‐NS was determined to be 106.3°C, and in the glass transition as well as rubbery regions, it was observed to compete with the E′ value of the control GE composites. Fractography was done using micrographs obtained from environmental scanning electron microscope (ESEM). Traces of polymeric material found at the fiber surface certified the improved interfacial adhesion between glass fiber and polymer in the matrix‐modified composite samples. [ABSTRACT FROM AUTHOR]

The potential advantage of plasma treated polyethylene (PEP) in mechanical properties was studied in this research. Recycled carbon fiber (CF) was the filler used for this hand layup technique. During fabrication, 4–14 wt% CF was incorporated into PEP and the results showed the impact of both filler and plasma treatment in enhancing the mechanical strength of polymer composites. Tensile results improved from 17.51 to 22.51 MPa in the polyethylene (PE) matrix. Scanning electron microscope (SEM) results showed untreated PE composites with fiber and matrix breakages as also voids reducing the compatibility of the PE/CF phases. The maximum flexural property of 25.5 MPa was observed in 10 wt% CF/PE treated with plasma. This combination was tried with different fabrication conditions in a temperature range of 180–220°C and time duration of 20–30 min. It was clearly seen that CF/PE combinations at a temperature of 180°C and time duration of 20 min had maximum tensile and flexural strength. The optimization using Taguchi method proved the significance of CF content in enhancing the mechanical properties. It also observed better tensile strength, flexural strength properties with 10 wt% CF, 180°C temperature, 20 min time from the results. Surface images of this condition showed more dispersed CF in the PE than other combinations due to optimum temperature and time duration during fabrication. [ABSTRACT FROM AUTHOR]

3D printing of continuous fiber reinforce plastics (CCFRP) with fused deposition modeling is a burgeoning manufacturing method because of its exceptional mechanical properties. Nevertheless, it cannot manufacture parts at high speeds. Using laser heating instead of the traditional resistive heating in 3D printing of CCFRP has the potential to improve printing speed owing to its high heating efficiency. In this article, a process of laser‐assisted rapid 3D printing of CCFRP is proposed. The heating process of CCFRP by laser is analyzed and verified. The linear relation between printing speed and laser power is established. The experiments demonstrate that the printing speed is increased to 30 mm/s with the laser. The mechanical properties of printed parts, though enhanced as the printing speed and laser power increase, are better than those obtained by traditional methods. Scanning electron microscope images and experiments reveal that proper laser power is conducive to the melting of plastics, strengthening interlayer bonding, and reducing voids under roller pressure. Nonetheless, excessive laser power ablates the plastic, resulting in increased voids. [ABSTRACT FROM AUTHOR]

By using SU‐8010 thermal field scanning electron microscope, JEM‐2100 transmission electron microscope, MHRS‐150 Rockwell hardness tester and X‐ray diffractometer to observe the microstructure and detect residual stress, and the measurement of the hardness and the tensile properties, the effect of stabilization treatment on the microstructure, size change, and mechanical properties of the austempered M50 steel is studied. Results show that the residue of austenite and the carbides precipitated during the bainite transformation after austempering lead to lattice shrinkage, which reduces the size of the bearing ring. The release of quenching stress after tempering increases the size. During austempering and tempering, the size fluctuates between −0.29 and 0.23 mm. After the bearing ring is stabilized for 3 times, the precipitation of filamentous carbides reaches the maximum, and the number of carbides does not increase obviously after 5 times of stabilization. The size fluctuation range is −0.9 to 0.7 μm. After M50 steel is stabilized, the transformation of residual austenite to martensite and the precipitation of carbides increase the hardness, and the coarsening of carbides reduces the ductility. The tensile strength increases from 2550 to 2650 MPa, which is related to the dispersion strengthening of carbides and their pinning effect on dislocations. [ABSTRACT FROM AUTHOR]

Fracture of cathode secondary particles is a critical degradation mechanism in lithium‐ion batteries. The microindentation strength of LiNi0.8Mn0.1Co0.1O2 secondary particles is measured in situ in the scanning electron microscope (SEM), enabling dynamical imaging of fracture. Crack propagation is intergranular between primary particles when induced by compressing between flat platens (analogous to calendaring), and with a cono‐spherical indenter (representing particle‐particle contact). Fracture occurs directly beneath the cono‐spherical tip and at the centre of secondary particles when compressed between flat platens. Finite element modelling of stress states provides insight into the dependence of fracture load upon cohesive strength and particle toughness. Secondary particle indentation strength decreases with increasing secondary particle size, with cycling, and with increasing state of charge. The indentation strength decrease is greatest in earlier stages of delithiation. The novel microindentation technique allows assessment of strength and toughness of different cathode morphologies, aiding prediction of optimal particle structure and processing conditions. [ABSTRACT FROM AUTHOR]

In this study a highly flexible microwave shielding material was fabricated by solution casting method utilizing Nickel and biocarbon particles in PVA matrix and characterized for mechanical, magnetic, and microwave shielding properties. The main aim of this study was to prove the significant role of magnetic particles in electromagnetic interference (EMI) shielding along with conductive particles. The results show that the addition of Ni‐biocarbon hybrid particle increases the shielding properties up to 56.5 dB at 20 GHz. The magnetic permeability increased gradually with the inclusion of Ni particles with a highest magnetization, coercivity, and retentivity of 1250 E−6 emu, −9000 G, and 1100 E−6 emu. Similarly the mechanical results show that adding biocarbon enhances the composite's mechanical properties. A highest tensile strength, tear strength, elongation, and hardness are noted as 38, 168 MPa, 18.4%, and 36 Shore‐D. Comparatively, the hardness and elongation% of composite designations contains 3 and 5 vol% of hybrid particles have increased by 9% and 26%, respectively, in comparison to composite containing only 5 vol% of biocarbon with PVA. Scanning electron microscope fractography indicates biocarbon particles reduce voids and improve adhesion. These flexible EMI shielding composites could be used in telecommunication and other wave transmitting devices in engineering applications. [ABSTRACT FROM AUTHOR]

The present work is an attempt to study the effect of different surface treatments of flax fiber on the mechanical properties of the natural fiber reinforced natural rubber (NR) composites. In this study, flax fiber was chopped to 1, 1.25, and 1.5 cm in length and mixed with NR in two roll mill. The composite of 20%, 30%, 40%, and 50% fiber loading was prepared from each fiber length. Tensile analysis showed that a 1.25 cm fiber length composite of volume 40% has higher tensile strength compared to others. Hence, this optimized the fiber length and loading has opted for further study. Flax fiber was treated with NaOH and laccase and reinforced into an NR matrix. Properties like tensile strength, hardness, relative density, water diffusion, scanning electron microscope (SEM) and Fourier‐transform infrared spectroscopy (FTIR) for surface treated and untreated natural fiber‐reinforced NR composites have been investigated and compared. The reduction in the hydrophilic characteristics of the NaOH and laccase treated fiber was evident from FTIR analysis and increase in the crystallinity index of the fiber depicted by X‐ray diffraction (XRD) results. SEM analysis showed the enhanced interfacial interaction of treated flax fiber NR composite compared to untreated composite due to the removal of non‐cellulosic contents in fiber and an increase in the surface roughness after treatments. Further, an increase of 9% and 27.4% in tensile and tear strength was found in NaOH treated flax fiber reinforced NR composite. [ABSTRACT FROM AUTHOR]

Chitosan (CS) fibers have been applied in various fields due to their biocompatibility, biodegradability, and antibacterial properties. However, weak mechanical properties remain as obstacles to further applications. Silk nanofibrils (SNFs) extracted from natural silk fibroin fibers preserve outstanding mechanical properties at the nanoscale, which are expected to impact structural programming and mechanical reinforcement for CS fibers. In this study, wet‐spun CS/SNFs composite fibers were continuously collected from NaOH/ethanol coagulation. Scanning electron microscope (SEM) results showed that SNFs were uniformly distributed in the CS matrix, and obvious orientation was observed when the mass ratio of SNF/CS was 75/100. Tensile tests showed that the introduction of SNFs significantly enhanced the mechanical properties of CS fibers when the mass ratio of SNF/CS was more than 25/100. With the increasing of SNF content, the tensile strength gradually increased, and the tensile strength and modulus could be increased 2.9 times and 3.5 times, respectively, when 100% SNF was added. The improvement of mechanical properties was partially attributed to hydrogen bonding between SNF filaments and CS, which was confirmed by FTIR and XRD results. This study provides a facile and eco‐friendly method to spin CS fibers with enhanced mechanical properties and a hierarchical structure. [ABSTRACT FROM AUTHOR]

In this research, rotomoulded samples of polyethylene (PE) were mechanically tested to find better applications. The mold was kept in an oven at 260°C with forced convection. Total fabrication time depended on peak internal air temperature (PIAT) used with 200, 220 and 240°C to confirm the fabrication conditions. The plasma treatment of PE and recycled carbon fiber (CF) was used for the improvement of properties. Maximum tensile strength (TS) of 23.1 MPa was observed in 10 wt% CF/PE composites. Scanning electron microscope (SEM) results revealed good mechanical interlocking with higher chemical interaction of carbon fiber of up to 10 wt% with plasma polyethylene leading to good mechanical properties in the composites. Flexural strength (FS) of 19.98–26.02 MPa in the properties was observed plasma treated in the PE with CF (3–10 wt%) combination. Agglomeration in the carbon fiber lowered flexural properties of 13, 15 wt% filler with both plasma and non‐plasma PE. The CF (3–10 wt%) with plasma PE showed enhanced impact strength (IS) from 6.84 to 8.64 KJ/m2. Maximum TS, FS and IS were observed with peak internal air temperature (PIAT) of 200°C. Surface images showed even distribution of fiber and resin in the plasma treated matrix in 5 wt% CF combinations. The differential scanning calorimetry (DSC) results do not show fluctuations in the melting and crystallization temperatures of the samples after plasma treatment. [ABSTRACT FROM AUTHOR]

In this work, a chemical precipitation procedure for decorating graphene oxide (GO) with Fe2O3 nanoparticles was described. Iron(III) chloride (FeCl3) was employed to generate the nano‐Fe2O3 particles onto the GO surface in the presence of sodium hydroxide. The Fe2O3@GO hybrid was characterized by various techniques of X‐ray diffraction, Fourier transform infrared spectroscopy, Field‐emission scanning electron microscope, Raman spectra, and Atomic‐force microscopy. The epoxy (EP)‐matrix nanocomposites containing various Fe2O3@GO loadings (0–0.8 wt% at a step of 0.2) were prepared by mechanical stirring and ultrasonic treatment. Mechanical properties of these composites were explored using the three‐point bending and dry‐sliding wear tests. The results revealed that the best flexural and wear behaviors were related to the specimens containing 0.2 and 0.6 wt% Fe2O3@GO hybrid, respectively. The incorporation of 0.2 wt% Fe2O3@GO was found to increase the flexural strength and modulus by 24% and 29%, respectively. Additionally, mass reduction and friction coefficient were decreased by 97% and 66% respectively, due to the addition of 0.6 wt% Fe2O3@GO. Most importantly, in comparison with the untreated‐GO/EP composite, the specimens containing Fe2O3@GO have attained higher improvements in flexural and wear properties. Finally, morphology of the fractured and worn surfaces was also evaluated. [ABSTRACT FROM AUTHOR]

The current research article assesses the feasibility of recycled CFRP (Carbon‐Fiber‐ Reinforced‐Polymer) fibers in high‐strength concrete. Different dosages of recycled CFRP fibers (0.2%, 0.4%, 0.6%, 0.8%, and 1%) as well as different aspect ratios of CFRP fibers with 10 and 20 mm fiber lengths is assessed for hardened state characteristics of reinforced high‐strength concrete. Furthermore, ultrasonic pulse velocity test, compression test, flexure test, and impact resistance test are performed to understand the hardened properties of specimens. The chemical composition of various elements present in the various kinds of concrete samples is qualitatively and quantitatively found with the help of energy‐dispersive X‐ray spectroscopy (EDX) equipment. To understand the surface morphology of carbon fibers incorporated in concrete samples, Scanning electron microscope (SEM) photographs are obtained to examine the prepared samples thoroughly. Linear regression analysis, an analytical analysis technique, is incorporated to linearly correlate the different hardened mechanical characteristics of specimens taking into account varying lengths and different dosages of recycled CFRP fiber. The findings reveal that increasing the CFRP fiber dosage and the aspect ratio of recycled CFRP fiber improves the reinforced mix composition's mechanical characteristics. [ABSTRACT FROM AUTHOR]

Although poly(L‐lactic acid) (PLA) has been widely studied and used in biomedical areas because of its well‐known biocompatibility, degradability and renewability, its potential application is still greatly limited by its brittleness and poor ductility. In this work, we, for the first time, reported a series of multi‐urea linkage segmented ultra‐strong thermoplastic polyurethane‐urea (PUU) copolymers using PLA and poly(ε‐caprolactone) as the mixed soft segments and water as an indirect in situ chain extender. The tensile strength, elongation at break and tensile modulus of the obtained PUU copolymers are 45–52 MPa, 380–540% and 180–430 MPa, respectively. After a simple one‐step uniaxial tensile deformation was applied to these PUU copolymers, their tensile strength and tensile modulus could be dramatically increased to 200 and 630 MPa, respectively, while maintaining enough good ductility (elongation at break >50%). Scanning electron microscope and Wide‐angle X‐ray Diffraction results showed that the dramatically improved mechanical performance should be mainly attributed to their more oriented microstructures. This study provided an easy strategy to pursuing synthetic PLA based biopolymers combining with ultrahigh mechanical strength and biocompatible and degradable properties. [ABSTRACT FROM AUTHOR]

Based on the viscous energy dissipation parameter around the crack tip, several intrinsic factors tend to govern the dissipation factor which in turn leads to the characteristic crack growth mechanism of the rubber vulcanizate. Herein, the crack growth behavior of different filled natural rubber (NR), styrene butadiene rubber (SBR), and NR/SBR blends was studied. It was deciphered that the 80/20 NR‐SBR (NSS) compound exhibited the lowest crack growth (dc/dn) value at all strain percentages which was in good accordance with its highest viscous energy dissipation as observed from the DMA (strain sweep) results. Also, from the theoretical calculations, dissipated energy per unit volume for NSS was 4.73 MPa, which was the highest out of all the compounds. This led to a decrement in crack growth. The lowest intensity peak in tan δ versus temperature curve, 6.5% decrement in ΔE'(storage modulus), and almost 44% decrement in ΔG' (Payne Effect) indicates higher polymer‐filler interaction and lower filler‐filler disintegration respectively, as compared to 100 NR (NRS). The results from optical microscopy and scanning electron microscope suggested that NSS exudes the smallest crack deviation and extent of crack growth with lesser filler agglomerates making NSS the best fatigue‐resistant compound. [ABSTRACT FROM AUTHOR]

The degree of the imidization reaction determines the properties of polyimide (PI) obtained by the thermal curing process. In this paper, amine‐modified graphene (N‐GO) was designed by integrating pyridine structure with graphene and acting as a catalyst to promote the imidization reaction of PI. Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) were then used to confirm the morphology and structure of N‐GO. The catalytic effect of N‐GO in imidization reaction was obtained by FTIR and subsequently characterized by differential scanning calorimetry (DSC) and water contact angle (WCA). Surprising results suggest that the agglomeration of N‐GO can also contribute to solid‐phase reactions in imidization reactions. Lastly, the results of mechanical property tests, thermogravimetric analysis (TGA), and FTIR demonstrated that the composite films showed excellent tensile strength (176.2 MPa) and thermal stability (513.0 °C); at the same content, only 0.5% of N‐GO addition reduced the imidization temperature by 20°C, exhibiting remarkable enhancement effects. This research is a valuable solution to the problem in performance caused by low‐temperature curing agent residues in films, and it is expected to be used in the microelectronics field. [ABSTRACT FROM AUTHOR]

The intention of the present study was to synthesize Gum ghatti‐cl‐poly(acrylic acid)/‐o‐MWCNT hydrogel by free radical copolymerization method where the role of various ingredients are as: Gum ghatti as biopolymer (GG), acrylic acid (AA) as a probe for synthetic monomer, ammonium persulfate as initiator and methylene bis‐acrylamide (MBA) as a crosslinker. The oxidized multiwalled nanocarbon tubes (‐o‐MWCNT) with variable amounts (0–50 mg) were used as fillers. The as‐prepared hydrogels were characterized by X‐ray diffraction, scanning electron microscope and Fourier transform infrared spectroscopy. The rheological investigation of hydrogels revealed that the storage modulus (G′) was always higher than the loss modulus (G″) in the linear viscoelastic region over the entire frequency range. The persistent covalence crosslinking is responsible for the solid‐like behavior and elastic nature (G′ > G″). Hydrogels containing Gum ghatti‐cl‐poly(acrylic acid)/‐o‐MWCNT increased with strain. The nonlinear oscillatory shear increases by the addition ‐o‐MWCNT. The features shown highlight the potential of Gum ghatti‐cl‐poly(acrylic acid)/‐o‐MWCNT hydrogels for agricultural, medicinal, and pharmaceutical applications. [ABSTRACT FROM AUTHOR]

It is aimed to explain different tensile elongations in 18Cr–8Ni austenitic stainless steel (ASS) with various microstructures having the same yield strength by comparing the deformation mechanisms. The as‐received ASS is cold‐rolled (CR) at room temperature with thickness reductions of 10% and 90% (achieved following 14 passes). The ultra‐fine grain/fine grain (UFG/FG, average grain size (diameter): 0.5–2 μm) structure is developed by annealing the 90% CR structure at 850 °C over 300 s. The optical, scanning and transmission electron microscope, electron backscatter diffraction, and X‐ray diffraction techniques are applied to the microstructural features. The as‐received specimen contained equiaxed austenite and equiaxed dislocation cells, stacking faults, deformation twins (DTs), and strain‐induced martensite (SIM) coexist in the 10% CR and UFG/FG samples. Tensile tests are conducted, and the results reveal that 10% CR and UFG/FG structures exhibited similar yield strengths (550 MPa) under conditions of varying elongation properties, which is attributed to differences in the microstructure‐dependent deformation mechanisms. Dislocation slip (≈10 area%; newly formed), DTs, and SIM (≈44 vol%; newly formed) are observed in the 10% CR structure. The presence of numerous dislocation slips (≈50 area%; newly formed) and a small amount of DTs and SIMs are observed in UFG/FG structure. [ABSTRACT FROM AUTHOR]

In this study, the effect of sonication time on the mechanical properties of graphene nanoplatelets (GnPs) glass fiber composites were discussed. The Sonication process is one of the best techniques to ensure uniform dispersion of nanofillers into the polymer matrix; otherwise, they form agglomerates of multilayers. To fulfill the massive demand for mass production, ultrasonic bath‐type sonication were deployed. In this study, 0, 1, 2, 3, 4, and 5 wt% of GnPs were added with epoxy at different sonication durations, precisely 0, 20, 40, and 60 min. Other sonication process parameters were kept constant with a sonication frequency of 28 KHz. Bidirectional glass fabric materials was used as reinforcement material in the fabrication of the laminates. In total, 21 laminates were fabricated using the hand lay‐up technique in various amalgamations. The tensile and flexural specimens were cut from the laminates as per the standards to determine their mechanical properties. The scanning electron microscope (SEM) images were used for the structural analysis of the glass fiber reinforced GnPs/epoxy composite. Surface morphology of GnPs becomes more wrinkled, resulting in a stronger graphene/epoxy matrix interface, enhancing the tensile strength and tensile modulus performance of the nano‐composites increases up to 37.12% and 66.30%, the flexural strength and flexural modulus performance of the nano‐composites increases up to 55.74% and 91.23% respectively. Based on the investigations, the influence of the GnPs percentage and the sonication duration for the preparation of the nano‐composites with the help of technique for order of preference by similarity to ideal solution (TOPSIS) optimization technique. [ABSTRACT FROM AUTHOR]

The need for eco‐friendly materials has been attracted due to renewability, abundance availability, low cost, and so on. Therefore, the search for bio fillers for the fabrication of bio‐based composite materials is gaining more and more attention in both academic and industry circles because it promotes sustainability. The present study represents the utilization of biomass solid waste in the hybrid form of Tamarind Seed and Date Seed Filler (TSF/DSF) into polymer reinforced composite which has been explored for the first time by a compression molding technique. These fillers are bio‐waste that can be obtained at a minimal cost from renewable sources. An attempt has been made to use these hybrid fillers to reinforce the matrix ranging from 0 to 50 wt%, and their physical, mechanical, and thermal properties were investigated. In general, the inclusion of hybrid fillers increases mechanical properties, although the addition of hybrid fillers had only a minor impact on thermal properties. When compared to the pure vinyl ester resin, the hybrid fillers reinforced composites revealed a significant enhancement in tensile, flexural, impact, and hardness properties, with improvements of 1.51 times, 1.44 times, 1.87 times, and 1.46 times respectively, at 10 wt% filler loading. Filler matrix interaction of fractured mechanical testing samples was evaluated by scanning electron microscope. Based on the findings, hybrid filler reinforced composites may be suitable for applications where cost is a consideration and where minor compromises in thermal qualities are acceptable. [ABSTRACT FROM AUTHOR]

The present work aims to demonstrate the effect of multiwalled carbon nanotube (MWCNT) on mechanical behavior and damage of woven carbon fiber/epoxy composites through experimental characterizations and multi‐scale modeling. Tensile tests were conducted for MWCNT/epoxy nanocomposites, and carbon nanotube (CNT) reinforced laminated open hole composites with different MWCNT weight ratios. The tensile modulus in CNT/epoxy nanocomposite was enhanced by 15.0%, 37.86%, and 22.86% for MWCNT reinforcement of 0.5%, 1.0%, and 1.5% wt, respectively. The corresponding improvement of tensile modulus for woven composites was 3.45%, 10.25%, and 1.53%; whereas tensile strength was increased by 19.76%, 25.78%, and 6.70%. The enhancement of tensile modulus and strength was less for 1.5% wt MWCNT laminates due to the formation of MWCNT agglomeration. The effective elastic isotropic/orthotropic properties for nanocomposite/woven composite were estimated through Mori‐Tanaka approach and numerical homogenization. The finite element simulations were performed with Hashin's damage model and extended finite element method‐based crack growth study. The delaminations between layers have been demonstrated through cohesive zone modeling. Damage propagation, interface delamination, and fiber/matrix failure were demonstrated by numerical simulations in line with scanning electron microscope observations. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (RGO) is an effective polymer filler for shielding against electromagnetic interference (EMI). Its shielding efficiency rises as its concentration in polymer matrices increases. However, higher filler loading impedes polymer foaming and deteriorates the mechanical properties of the resulting foam. The goal of this work is to determine the optimal RGO concentration that can be loaded into polyurethane (PU) matrix to produce a composite foam with a high level of electromagnetic shielding along with good mechanical properties. To that end, different PU foam samples containing varying amounts of RGO were synthesized. The synthesized samples were characterized by scanning electron microscope (SEM), thermogravimetric analysis (TGA), Fourier transform infra‐red (FT/IR) and universal testing machine. Furthermore, the shielding efficiency of the samples was measured using a vector network analyzer over the frequency range of 8–12 GHz. The results revealed that the increase in RGO concentration enhances the mechanical and thermal properties of the prepared composite foam materials. The shielding effectiveness reached −23 dB at 5 wt% RGO concentration. The polyurethane‐RGO composite foam materials have been identified as potentially viable materials for use in electromagnetic shielding applications. [ABSTRACT FROM AUTHOR]

In this study, S‐doped graphene (SG) powders were produced in one‐step green and environmental‐friendly, quick, and cheap route of Yucel's method. Different sulfur functional groups were formed on graphene surfaces by changing the anodic potential range and were first used to prepare SG/polylactide (PLA) nanocomposites. The influence of applied potential on the structural properties of SG powders was explored through cyclic voltammetry (CV), X‐ray photoelectron spectroscopy (XPS), X‐ray diffractometry (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and BET surface area analysis. S‐doped graphenes were subsequently melt mixed with polylactide at low contents of 0.1 and 0.5 wt% using a twin‐screw extruder. The interaction of SGs functional groups with PLA and its effect on the nanocomposites' final morphological, thermomechanical, and tensile properties was then studied. It was revealed that the tensile strength and modulus of the nanocomposites were noticeably increased with the addition of such low SGs contents. The applied potential and hence the structural properties of SGs differently influenced the final tensile properties of the nanocomposites. A maximum enhancement of around 100% in tensile strength was observed using only 0.1 wt% SG produced at the potential range of −1.5 and 2.3 V. [ABSTRACT FROM AUTHOR]

The mechanical and thermal characterization of Moringa oleifera fiber and red mud (RM) reinforced chitosan (CS) based hybrid composite is the subject of this research. By varying the percentages of M. oleifera fiber and RM in the hand lay‐up process, seven types of composite samples were developed. Tensile, flexural, compression, and impact testing were performed in accordance with ASTM standards. A scanning electron microscope was used to examine the cracked surfaces of the tested specimens. Hybridization with M. oleifera fiber and RM increased the characteristics of CS composites, according to the findings. Increase in the percentage composition of RM resulted in better mechanical characteristics of fiber‐reinforced composites. C6 type composite revealed maximum tensile strength of 65.59 MPa and impact strength of 24.86 kJ/m2. It also had better dynamic mechanical qualities, while C6 composite had the best static and dynamic mechanical properties. Overall it may be concluded that composites can be utilized in light weight structural applications. [ABSTRACT FROM AUTHOR]

The deposition samples of Cr12MoV with different scanning speeds are prepared by laser melting deposition technology. Compared with forged Cr12MoV, the mechanism of laser melting deposition technology to improve hardness and wear resistance is studied. The tensile specimens of as‐deposited Cr12MoV are prepared by using the optimal process parameters. The fracture mechanism of as‐deposited Cr12MoV and the effect of deposition direction on its mechanical properties are studied. The phase composition and microstructure of deposited and forged samples are studied by X‐Ray diffractometry (XRD) and scanning electron microscope (SEM). The results show that the martensite in the as‐deposited Cr12MoV sample increases and has a finer grain size, which achieves the effect of fine‐grain strengthening. The hardness and wear resistance of the deposited Cr12MoV samples at three laser scanning speeds (4, 8, and 12 mm s−1) are better than those of the forged samples. The tensile fracture mode of the deposited Cr12MoV sample is an intergranular brittle fracture, and the sample perpendicular to the laser scanning speed has higher tensile strength and more excellent elongation. [ABSTRACT FROM AUTHOR]

Delamination is always considered as a threat to the resin matrix composite laminates due to the nonvisibility from the outside. Much effort on the interleaving toughening has been made to improve the interlaminar fracture toughness. The synergistic toughening effect of thermoplastic resin and carbon nanotubes (CNTs) has been the topic in the interleaving toughening. In this study, the influence of the hybrid structure between thermoplastic polyetherketone‐cardo (PEK‐C) and CNTs on the toughening efficiency was investigated. The mode II interlaminar fracture toughness was tested and the fracture surface was examined by scanning electron microscope. The results showed that the interlaminar structure was closely related with the interlayer structure and the synergistic toughening effect depended greatly on the hybrid structure. [ABSTRACT FROM AUTHOR]

Herein, the effect of tempering temperature on the microstructure evolution and mechanical properties of a new nitrogen‐containing hot‐work die steel 3Cr7Mo2NiSiVN is investigated. The new type of hot‐work die steel is quenched at 1080 °C and then conducts a double tempering from 200 to 700 °C. The quenching microstructure contains martensite, film‐retained austenite, and undissolved precipitates, and these precipitates play a Zener pinning effect role in prior austenite grains growing. Based on the Thermo‐Calc thermodynamic calculation and experimental results, the die steel contains V‐rich M2N nitride, Cr‐rich M23C6 carbide, Mo‐rich M6C carbide, and (Nb,V)‐rich M(C,N) precipitates. A secondary hardening phenomenon occurs and the brittle fracture turns to ductile fracture under the scanning electron microscope (SEM) field when the tempering temperature is 500 °C. Room strength decreases and the plasticity improves with the continual increase of tempering temperature. Many nano‐size spherical M2N nitride and strip‐like M(C,N) carbonitride precipitate when the tempered temperature exceeds 550 °C with transmission electron microscope (TEM) observation. Finely dispersed M2N nitride and M(C,N) carbonitride are beneficial for stabilizing microstructure at high temperatures and improving high‐temperature strength. Therefore, the high‐temperature strength of the new type of hot‐work die steel is much higher than that of the traditional hot‐work die steel. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate and compare the mechanical properties and ceramic bond of additively manufactured and milled dental zirconia materials. Materials and Methods: Disc (r = 10 mm, h = 2 mm) and bar (25×$\ \times \ $4 × 1. 2 mm) shaped milled (M group) (Nacera Pearl; Doceram) and additively manufactured (AM group) (NanoParticle Jetting; XJet, Carmel 1400) zirconia specimens were prepared for 2 experimental groups. Ceramic was applied to the disc specimens (h = 4 mm, r = 6 mm) (n = 9) and their shear bond strength (SBS) was measured. The surface morphology of disc specimens was analyzed with a scanning electron microscope (SEM). The Vickers microhardness (Vh), surface roughness (Ra), and three‐point flexural strength (FS) of bar specimens (n = 9) were measured. Results were statistically analyzed with Mann‐Whitney U‐test (α = 0.05). Results: Significant differences were found in FS and Vh values of the M and AM groups. M group (1501.4 ± 60.1 HV1) showed a significantly higher Vh value than the AM group (1169.2 ± 48.4 HV1) (p < 0.001). FS of the M group (1287.5 ± 115.2 MPa) exhibited significantly high value than the AM (1030.0 ± 29.2 Mpa) group (p < 0.001). Statistically, no significant differences were seen in SBS and Ra values of the M and AM groups. Conclusion: Within the limitations of this in vitro study, the manufacturing technique affected the mechanical properties of the zirconia materials. AM zirconia material showed lower Vh and FS values than M zirconia. Additionally AM zirconia demonstrated adequate bond strength with dental ceramic. [ABSTRACT FROM AUTHOR]

Dihydroxyl poly(1,3,4‐oxadiazole) (DHPOD) polymers are synthesized by copolymerization of 2,5‐dihydroxyterephthalic acid (2,5‐DHTA) and terephthalic acid with hydrazine sulfate in oleum, and then DHPOD fibers are prepared by wet‐spinning. The effects of UV irradiation on POD fibers' mechanical properties and surface morphology with and without hydroxyl groups were investigated. As proved by tensile testing and scanning electron microscope measurement, the UV resistance of DHPOD fibers is improved compared to that of p‐POD fibers. Besides, the heat resistance of POD fibers is not damaged by the introduction of phenolic hydroxyl groups. The UV and fluorescence spectra are used to analyze the UV resistance mechanism of the POD containing phenolic hydroxyl groups. Results show that the UV resistance mechanism of DHPOD is related to the proton transfer reaction between the 1,3,4‐oxadiazole ring and ortho phenolic hydroxyl group. [ABSTRACT FROM AUTHOR]