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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]

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]

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 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]

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]

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]

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]

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]

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]

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]

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]

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]

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 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]

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]

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]

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]

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]

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 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]

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]

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]

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]

Cyanate ester (CE) was employed to modify epoxy resin (EP) by chemical reaction, and the thermal, mechanical, and corrosion properties were systematically studied. Differential scanning calorimetry and Fourier transform infrared spectra were carried out to determine the curing kinetic parameters, suitable curing procedure, and reaction mechanism. The glass transition temperature and thermal stability were investigated employing dynamic mechanical thermal analysis and thermogravimetry measurement. Furthermore, the mechanical and corrosive properties were evaluated, using test techniques such as mechanical testing machine, abrasion tester, axle rod flexibility tester, scanning electron microscope, and electrochemical impedance spectroscopy. Results verified that an appropriate amount of CE could significantly improve the comprehensive performance of EP. However, a satisfactory effect would not be achieved when the modifier is inadequate or excessive. [ABSTRACT FROM AUTHOR]

In the present work, an experimental investigation is performed to study the influence of process parameters on mechanical properties of tetra‐anti‐chiral auxetic structures manufactured by material extrusion (ME) technique of additive manufacturing (AM). Process parameters namely layer height, print speed, and print temperature are considered, while responses are compressive strength (σ), modulus (E), and specific energy absorption (SEA). Specimens of acrylonitrile‐butadiene‐styrene (ABS) polymer are fabricated and then tested under compressive loading. From the experimental results, it is observed that all process parameters significantly influence the mechanical properties of the structure. Scanning electron microscope (SEM) is used to study microstructural defects of the tested specimen. To maximize the responses, optimization of process parameter is performed using desirability function approach. Regressive models are developed to predict the mechanical properties. [ABSTRACT FROM AUTHOR]

In the present work, we studied the formation of sunflower oil nanoemulsion using ultrasound techniques. Later, we investigated the development of active films based on a mixture of whey protein containing sunflower oil base nanoemulsion with different concentrations (10, 25, and 50% of total whey protein). The prepared film was by analyzing using the Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and field‐emission scanning electron microscope (FE‐SEM). The film shows no changes in its integrity and crystallinity compared to the virgin film. The presence of nanoemulsion improves the mechanical properties from 2.75 MPa to 3.52 MPa while it decreases the water vapor permeability from 3.4 × 10–10 to 1.3 × 10−10g/m.s.Pa for concentrations NE (50% of Whey protein). The antioxidant activity for Tween 20 nanoemulsion is 38.7% compared to 36.1% for Tween 80 nanoemulsion. The antimicrobial activity of the film contains sunflower nanoemulsion higher than virgin films. The results showed the potential of blend film of whey protein with nanoemulsion for active films for novel food protection. [ABSTRACT FROM AUTHOR]

In the current study, three different curing kinetics models were used to analyze the curing kinetics of hyperbranched benzoxazine (HB‐PED230) and monofunctional benzoxazine (P‐a) modified cyanate ester (CE) resin by non‐isothermal differential scanning calorimeter. Moreover, the effects of two benzoxazines on the copolymerization behavior, thermal stability, and mechanical properties of CE resin were studied. Compared with the P‐a modified CE resin, HB‐PED230 greatly reduces the curing temperature of the copolymer, while improving the bending strength and impact strength. The curing temperature of HB‐PED230 modified CE resin was 79°C lower than neat CE resin, while the CE/P‐a blended resin only reduce 48°C. As the amount of HB‐PED230 increased, the flexural strength and flexural modulus of the copolymers were improved. Surprisingly, when 7 wt% of HB‐PED230 was added, the impact strength of the copolymer was increased by 177.6%, implying that the toughness of CE resin had been greatly improved. Moreover, the fracture morphology of the copolymers was observed by scanning electron microscope. In summary, a small amount of HB‐PED230 blending can effectively improve the overall performance of CE resin. [ABSTRACT FROM AUTHOR]

Reactive blending of polycarbonate (PC) with hydroxyl terminated polydimethylsiloxane (PDMSOH) enhances the impact strength at sub‐zero temperature and also influences the melt flow property of the modified PC. Both viscosity and concentration of the siloxane play role differently on modification of the properties. PDMSOH was incorporated in the polymer chains of PC by transesterification reaction in presence of alkali catalyst. Higher concentrations of siloxane though increased low‐temperature ductility but often at the expense of undue enhancement of melt flow property. Selection of PDMSOH of an appropriate viscosity however could overcome this problem. Different grades of siloxane modified PC could be developed having good impact strength at −30°C while simultaneously maintaining its desired melt flow property. Izod impact tester, melt flow index meter, viscometer, UV–Vis spectrometer and scanning electron microscope were used to characterize the material. This work will pave the way for developing desired grades of PC for low‐temperature applications. [ABSTRACT FROM AUTHOR]

This paper reports an experimental study of the influence of elevated temperature on alkali activated slag (AAS) and slag‐metakaolin (MK) systems. The residual compressive and flexural tensile strengths, ultrasonic pulse velocity (UPV) and porosity and water absorption ratios of AAS and AAS‐MK composites after subjected to elevated temperatures of 200, 400, 600, 800, and 1000°C were investigated. Two different procedures were applied for cooling the specimens. The changes in the microstructure of the composites after subjected to high temperature were examined with scanning electron microscope and X‐ray diffraction. Test results reveal that depending on the increasing temperature, the residual compressive strength, flexural tensile strength, and UPV values of the specimens decreased, and porosity and water absorption ratios increased. The minimum strength results of AAS and AAS‐MK specimens were observed at 800 and 600°C, respectively. In particular, there have been significant changes in the internal structure of AAS and AAS‐MK specimens exposed to 1000°C and new reaction products were observed. Test results have shown that AAS specimens are a new alternative that can be developed for use in environments exposed to high temperatures. Since this new composite contains only slag binder and slag aggregate, it can be an economical product that use fully recycled material and these properties can increase the application areas of environmentally friendly material. [ABSTRACT FROM AUTHOR]

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This study compares the mechanical properties of rice husk (RH) and rice husk ash (RHA) filled polypropylene (PP) composites and the effects of ethylene‐acrylic‐ester‐maleic anhydride (E‐AE‐MA) and PP‐g‐maleic anhydride (MAPP) as compatibilizer. In this study, PP/RH and PP/RHA composites were blended at the ratios of 85/15 wt% and compatibilizers at four parts per hundred each, via melt extrusion in a twin‐screw extruder prior to injection molding. Mechanical tests were tensile, flexural and impact tests. A morphological study was conducted by scanning electron microscope (SEM). Results show that PP/RHA composite exhibited a 4% significant increase in tensile strength compared to PP/RH composite (р ˂ 0.05) while, PP‐RH composite increased significantly by 5 and 3% in flexural and impact strength compared to PP‐RHA composite (р ˂ 0.05). MAPP increased significantly the flexural strength of PP‐RH and PP‐RHA composites by 23 and 21% (р ˂ 0.05) compared to E‐AE‐MA. PP‐RHA‐MAPP composite increased significantly the impact strength by 18% compared to PP/RHA/E‐AE‐MA composite (р ˂ 0.05). There was no significant difference in impact strength between PP/RH/MAPP and PP/RH/E‐AE‐MA composites (р ≥ 0.05). Overall results indicate that RH imparts better reinforcing effect in PP composite than RHA, while MAPP is a better compatibilizer. SEM study indicates that both compatibilizers improved the filler‐matrix interfacial adhesion. [ABSTRACT FROM AUTHOR]

Phenyl terminated hyperbranched polyesters (HBP‐Bs) were synthesized based on Boltorn‐type hydroxyl terminated HBPEs and characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, and so forth. The prepared HBP‐Bs were used to toughen poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) directly by melt blending. The thermal properties, rheological properties, mechanical properties, and microstructure of the PHBV/HBP‐Bs blends were studied in detail. Comparing with pure PHBV, the crystallinity of the PHBV/0.5 phr HBP‐Bs blends decreased by 14.10% (from 64.39% to 55.04%), the impact strength increased by 158.30% (from 7.41 kJ·m−2 to 19.14 kJ·m−2), and the elongation at break increased by 400.00% (from 0.91% to 4.55%). It can be seen from the scanning electron microscope that the fracture surface of the PHBV/HBP‐Bs blends became rough with the increase of HBP‐Bs, even with large filamentous structures and tiny holes, which further demonstrated that HBP‐Bs acted as an excellent toughening effect on PHBV. [ABSTRACT FROM AUTHOR]

Nanoparticles have been widely used in the improvement of the mechanical and thermal properties of the epoxy matrix. In this study, the room temperature curing agent composed of acrylic acid and 2,4,6‐trimethyl‐m‐phenylenediamine was mixed with different concentrations of CeO2 nanoparticles into the epoxy resin (E51) to obtain a nanocomposite that can be rapidly molded and cured. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to study the curing behavior of nanocomposites and E51 with the synthesized hardener. Through tensile, flexural, and impact tests, the influence of the nanoparticles content on the mechanical and thermal properties of the prepared composites was discussed. The results showed that the curing process was completed in 4 h. An increase of 78.4% in tensile strength, 81.7% in flexural strength, and 122.0% in elongation were obtained for the cured nanocomposite having 5 wt% CeO2 loading compared to the neat resin. Thermogravimetric analysis result showed that the thermal stability increased with increasing of CeO2 nanofillers content. Finally, the scanning electron microscope revealed the fracture surface morphology of the composites. [ABSTRACT FROM AUTHOR]

The current research work presents a novel nonionic curing agent (AEDA) synthesized by utilizing ethylene glycol diglycidyl ether (EGDE), 3,4‐dimethoxyaniline (DI), and triethylenetetramine (TETA). Infrared spectroscopy and nuclear magnetic resonance spectroscopy were used to characterize the structure of AEDA curing agent. Non‐isothermal scanning calorimetry was used to determine the activation energy and curing conditions of epoxy resin in the curing process. An impact testing machine, a tensile testing machine and a scanning electron microscope (SEM) were used to analyze the impact strength, tensile strength, bending strength, and micromorphology of the AEDA/E‐51 system with different mass ratios. The results show that AEDA is an effective high‐temperature curing agent. For the AEDA/E‐51 system with the optimal mass ratio of 10:100, the best curing temperature is 92.15°C, and the post‐curing temperature is 135.65°C. Furthermore, the apparent activation energy (Ea) of 1670 J/mol, the pre‐exponential factor (A) of 3.7 × 10−4, and the reaction series (n) value of 0.76 are obtained for the AEDA/E‐51 system. The impact strength of AEDA/E‐51 epoxy resin polymer is 7.82 kJ/m2, tensile strength is 14.2 MPa, and bending strength is 18.92 MPa. The micromorphological results of the AEDA/E‐51 system are consistent with the results of DSC test and mechanical properties test. Hence, this study provides theoretical support for the practical applications of AEDA as curing agent. [ABSTRACT FROM AUTHOR]

Aiming at the problem of high brittleness of cement stone, we have studied the self‐emulsificating and self‐crosslinking modification of epoxy resin (EP) (E54), and the modified EP was used in oil well cement to improve the cement ring toughness and reduce the cement ring cracked. Using 2‐acrylamide‐2‐methyl propane sulfonic acid and acrylamide as modified monomers, benzoyl peroxide as initiator, and grafting modification method by free radical polymerization to obtain water‐borne epoxy resin (WBE). Fourier transform infrared spectrometer and 1H NMR were used to characterize the modified product, which showed that the WBE contained ─SO3H and ─CONH2 hydrophilic groups, and the connecting method of the hydrophilic side chain was clarified. WBE can achieve good dispersion in an aqueous solution, it can be stabilized for 30 min without stratified at a centrifugal speed of 6000 rpm; when the temperature is >80°C, it can be self‐curing. The addition of WBE can increase the flexural strength of cement stone by 48.3%, the compressive strength by 38.4%, and reduce the modulus of elasticity by 45.3%. Scanning electron microscope analyzed the mechanism of WBE to improve the toughness of cement stone, and found that after WBE cross‐linking, polymer films and three‐dimensional network structures are formed in the cement stone, making the cement structure more compact. WBE can effectively improve the mechanical properties of cement rings and can be used to improve cementing quality. [ABSTRACT FROM AUTHOR]

This paper emphasis the improvement of mechanical properties of AA7075‐T651 using friction stir processing through localized surface modification by adding nano boron carbide particles. The reinforcement techniques such as the groove and blind hole methods were used by changing reinforcements of nano boron carbide and a matrix of AA7075‐T651 surface composites volume percentages (2 %, 4 %, and 6 %) along with tool rotational speed and processing speeds. Optical microscopy, scanning electron microscope and x‐ray diffraction analysis were used to examine the particle dispersion for the surface composites and to correlate with the enhanced mechanical properties. Results revealed that high input parameters have given grain coarsening and precipitate agglomeration and low input parameters provide poor nugget metal consolidation and no vertical material flow. The L9 orthogonal Array designed and optimized the process parameters for enhancing the surface properties of processed samples. Mechanical properties like ultimate tensile strength, yield strength, hardness, percentage of elongation and impact strength were evaluated for the groove friction stir processing method and blind‐hole friction stir processing methods. From the results, it has been observed that the blind‐hole technique resulted in higher hardness and the homogenous dispersion of nano boron carbide particles in the stir zone than the groove method. Consequently, for blind‐hole friction stir processing, grey relational analysis (GRA) and particle swarm optimization (PSO) approaches were proposed to optimise process parameters. From the compared optimization results between grey relational analysis and particle swarm optimization, particle swarm optimization approach was shown the best optimization results. Successively, the optimum condition in the respective experimentation is accomplished. Based on these observation and results, final validation tests were carried by changing the volume percentages of reinforcement keeping tool rotation speed and tool processing speed as constant. It is apparent that dynamic recrystallization in aluminium alloy at the processed zone due to presence of heterogeneous nucleation sites with nano boron carbide particles. [ABSTRACT FROM AUTHOR]

In this paper, SiC coating was prepared using the polymer‐derived ceramic method; then the effect of nano‐alumina as a filler material was studied. First of all, polycarbosilane(PCS) was dissolved in xylene; after that, different amounts of nano‐alumina particles were added to the solution. The coating was deposited on the alumina substrate using the dip‐coating method; this was followed by sintering at 1200℃. The phase content and microstructure of the samples were studied by X‐ray diffraction and scanning electron microscope methods, respectively. Nanohardness, Young's modulus, and coating adhesion were investigated by a nanoindentation method. The sheet resistance was evaluated using the four‐point probe technique; also, the wear resistance of the coating was studied by applying the pin‐on‐disk method. It was found that the addition of the nano‐alumina filler up to 20 wt% drastically improved the adhesion and wear resistance of the SiC coating. [ABSTRACT FROM AUTHOR]