Search

Highlights As is well known, Laser print paper is usually produced with high‐quality chemical wood pulp. The laser print waste paper fiber (LPWF) is a high‐quality secondary fiber, and the research and development of high‐value utilization technology for laser print waste paper has attracted much attention in the field of renewable resource recycling. In this study, LPWF was used to reinforce poly(lactic acid) (PLA) composites in the field, and the composites were modified with bioenzyme, cationic polyacrylamide (CPAM), and nano‐silicon carbide (Nano‐SiC) to enhance the interfacial compatibility of LPWF/PLA composites. The study systematically investigated the effects of various modification methods on the characteristics and degradability of composites made from laser print waste paper fiber reinforced PLA resin matrix. The results showed that the mechanical properties of the composites treated with CPAM and Nano‐SiC were significantly improved, with tensile strengths of 54.3 and 59.5 MPa, and flexural strengths of 85.1 and 91.5 MPa, respectively, and the water absorption of the composites was reduced after the modification treatment, while the thermal stability was improved. The degradation performance of the composites in various water environments indicated that the inclusion of LPWF accelerated the water degradation rate of the composites, with the maximum degradation rate of the composite reaching 1.26% in 30 days. Laser print waste paper is an excellent quality recyclable fiber resource. Four modifiers were used to modify LPWF/PLA composites. Characteristics and degradability of the composites were investigated. Significantly improved properties of CPAM and Nano‐SiC modified composites. The degradation rate of composites is increased by the addition of LPWF. [ABSTRACT FROM AUTHOR]

It is well-known that energy consumption is increasing around the world on a daily basis. In the construction sector, a highly effective solution for reducing energy consumption involves exploring both modern and traditional buildings designed to adapt to climate changes. One promising approach is to use paper waste and bio-sourced materials as the basis for insulation. The purpose of this study was to improve the sustainability of buildings by using recycled waste materials that have a positive impact on the environment, people, and the economy. A novel insulating material composed of recycled paper waste and Ampelodesmos mauritanicus leaves and fibers was developed and used in non-load-bearing elements. The paper waste was transformed into pulp and mixed with the bio-sourced materials to create a composite material that exhibits excellent insulation properties. The resulting material is lightweight, durable, and cost-effective. Furthermore, different mechanical and thermal analyses were performed on specimens with varying dosage ratios. The results showed that the developed material has good thermal insulation, with a value of 0.027 W/m.K. [ABSTRACT FROM AUTHOR]

Currently, the composite industry is focusing on more environmentally friendly resources in order to generate a new range of biobased materials. In this manuscript, we present a new work using lignocellulosic wastes from the paper industry to incorporate into biobased epoxy systems. The manufactured materials were composed of kraft lignin, glass fiber, and a sustainable epoxy system, obtaining a 40% biobased content. Using a vacuum infusion process, we fabricated the composites and analyzed their mechanical and UV resistance properties. The findings reveal a significant correlation between the lignin content and flexural modulus and strength, showing an increase of 69% in the flexural modulus and 134% in the flexural strength with the presence of 5% of lignin content. Moreover, it is necessary to highlight that the presence of synthesized lignin inhibits the UV degradation of the biobased epoxy coating. We propose that the use of lignocellulosic-based wastes could improve the mechanical properties and generate UV resistance in the composite materials. [ABSTRACT FROM AUTHOR]

Traditional wood-based panels composed of wood and petroleum based adhesives is widely used in furniture manufacturing and construction industries. However, these adhesives are not biodegradable, inhibiting the recycling of artificial board. More seriously, the emission of carcinogenic formaldehyde will lead to severe pollution and environmental issues. This study presents a method for preparing self-bonding composites. Waste poplar powder is used as raw material in the biocomposite, in which exogenous lignin is added, and lignin is extracted from the waste of the paper industry - black liquor, which is beneficial to the environment and the recycling of resources. The resulting biocomposites are characterized by aldehyde-free, better strength, and water stability. The dimensional stability and mechanical strength, bending strength (84.40 MPa), and tensile strength (35.40 MPa) of the biocomposite are 2.0 and 1.6 times that of composites obtained by hot pressing without pretreatment and are 2.7 and 2.4 times that of medium density fiberboard (MDF), lignin plays an important role as an adhesive, which is the key to improving mechanical properties. Moreover, the biocomposite features higher water stability and fire resistance than the traditional wood fiberboard. In conclusion, the developed black liquor-wood biocomposites are potential alternatives used to replace the formaldehyde wood-based fiberboard. [Display omitted] • An aldehyde-free wood-based panel was prepared by a resource-saving method. • The flexural and tensile strengths are 84.40 MPa and 35.40 MPa. [ABSTRACT FROM AUTHOR]

Aerogels are an excellent alternative to traditional oil absorbents and are designed to remove oil or organic solvents from water. Cellulose-based aerogels can be distinguished as polymers that are non-toxic, environmentally friendly, and biodegradable. The compression measurement properties of aerogels are often evaluated using dry samples. Here, oil-soaked, hydrophobized cellulose aerogel samples were examined in comparison to dry samples with and without additional hemp fibers and various levels of starch for crosslinking. The samples were characterized by compression measurement properties and filmed to evaluate the regeneration of the sorbent with repeated use. Overall, the measurements of the mechanical properties for the dry samples showed good reproducibility. The Young’s modulus of samples with additional hemp fibers is significantly increased and also shows higher strength than samples without hemp fibers. However, samples without hemp fibers showed slightly better relaxation after compression. Oil acts as a weak plasticizer for all aerogel samples. However, it is important to note that the oil does not cause the samples to decompose in the way unmodified cellulose aerogels do in water. Therefore, using hydrophobized cellulose aerogels as sorbents for oil in a sea or harbor with swell means that they can be collected in their entirety even after use.

Featured Application: Determining Young's modulus is an important step in the analysis of any material that undergoes elastic deformation. A quick estimation of it can be performed using the finite element method (FEM) with the procedure presented in this paper. Knowing the mechanical properties of fiber-reinforced composite materials, which are currently widely used in various industrial branches, represents a major objective for designers. This happens when new materials are used that are not yet in production or for which the manufacturer cannot give values. Given the practical importance of this problem, several methods of determining these properties have been proposed, but most of them are laborious and require a long calculation time. And, some of the proposed calculation methods are very approximate, providing only upper and lower limits for these values. Experimental measurements are obviously the optimal solution for solving this problem, but it must be taken into account that this type of method consumes time and material resources. This paper proposes a sufficiently accurate and fast estimation method for determining Young's modulus for a homogenized fibrous material. Thus, the FEM is used to determine the natural frequencies of a standard bar, for which there are sufficiently precise classical methods to express the engineering constants according to the mechanical properties of the component phases of the homogenized material. In this paper, Young's modulus is determined for such a material using the relationships that provide the eigenfrequencies for the longitudinal vibrations. With the adopted model, transverse and torsional vibrations are eliminated by blocking the nodes on the surfaces of the bars. In this way, more longitudinal eigenfrequencies can be obtained, so the precision in calculating Young's modulus is increased. [ABSTRACT FROM AUTHOR]

With the high precision requirements and the trend of large-scale composite parts, the development of composite molds is imminent. The short carbon fiber (SCF) composite mold is mainly prepared by the technological process flow of composite sheet injection, the bonding of composite plates, and machining. However, the current process optimization method has not matured adequately, and there are still many shortcomings, for example, low precision and high cost. In this paper, the optimization method of SCF/polyetherimide (PEI) composite molds is proposed. Many experiments have been conducted, and the results show that the coefficient of thermal expansion of composite samples can be effectively reduced and the mechanical properties can be improved by optimizing the SCF weight ratio and carbon fiber length. The bonding strength of composite joints in a high-temperature environment can be improved by optimizing the bonding process parameters and modification by carbon nanotubes. Based on the above optimization method, the SCF/PEI composite mold is prepared, and the C-shaped beam composite part is fabricated by using this mold. Compared with the part made by aluminum mold, the shape accuracy of the C-shaped beam composite part is proven high through digital measurement technology. [ABSTRACT FROM AUTHOR]

Determining the properties of composite materials (knowing the properties of the component phases) is a primary objective in the design phase. Numerous methods have been developed to determine the elastic constants of a composite material. All these methods are laborious and require significant computing time. It is possible to make experimental measurements, but these too are expensive and time-consuming. In order to have a quick estimate of the value of the engineering constants of a new composite material (in our study a polymeric matrix reinforced with carbon fibers), this paper proposes a quick method for determining the homogenized material constants, using the finite element method (FEM). For this, the eigenfrequencies of a beam specimen manufactured by the studied composite material will be computed using FEM. The model will consider both phases of the composite, with the geometry and real size. The mechanical properties of the constituent's material phases are known. With the help of this model, the torsional, longitudinal and transverse vibrations of the beam are studied. Based on the eigenvalues obtained by this calculation, it now is possible to quickly estimate the values of homogenized material constants required in the design. An example for a fiber-reinforced polymer composite material is provided in the paper. [ABSTRACT FROM AUTHOR]

Based on the previous research on the energy absorption of foam metal materials with different structures, a composite blast-resistant energy-absorbing material with a flexible core layer was designed. The material is composed of three different fiber materials (carbon fiber, aramid fiber, and glass fiber) as the core layer and foamed iron–nickel metal as the front and rear panels. The energy absorption characteristics were tested using a self-built gas explosion tube network experimental platform, and the energy absorption effects of different combinations of blast-resistant materials were analyzed. The purpose of this paper is to evaluate the performance of blast-resistant materials designed with flexible fiber core layers. The experimental results show that the composite structure blast-resistant material with a flexible core layer has higher energy absorption performance. The work performed in this paper shows that the use of flexible core layer materials has great research potential and engineering research value for improving energy absorption performance, reducing the mass of blast-resistant materials, and reducing production costs. It also provides thoughts for the research of biomimetic energy-absorbing materials. [ABSTRACT FROM AUTHOR]

Featured Application: Our research is the second step toward both establishing a standard aging protocol as well as selecting methods useful for evaluating the degradation of dental materials. The durability and performance of dental composites are essential for ensuring long-lasting dental restorations. However, there is a lack of a standardized procedure for evaluating the lifespan of dental materials. Our proposal assumed that dental materials should be tested under aggressive aging conditions to accelerate materials' degradation in vitro and such an approach should simulate prolonged material usage in the oral cavity. A comprehensive examination of the impacts of three aging methodologies on various mechanical properties, including the flexural strength (FS), diametral tensile strength (DTS), hardness (HV), fracture toughness (FT), flexural fatigue limit (FFL), and microstructure of selected dental materials (Resin F, Flow-Art and Arkon), was conducted. The findings revealed that preformed aging results in an average reduction of 30% in the mechanical strength properties of the dental composites when compared to the control. Notably, a strong correlation was identified between FS and FFL post-aging whereas no such relationship was observed between these parameters and FT. This paper highlights the significance of aging tests for new dental composites and recommends a focus on flexural strength and fracture toughness to optimize costs and time efficiency. Furthermore, the establishment of a standardized test for fracture toughness in dental composites is recommended. It is proposed that a minimum flexural strength of more than 32–48 MPa after aging should be maintained. A more extensive analysis of commercially available materials is suggested to refine the proper evaluation methods for composite materials. [ABSTRACT FROM AUTHOR]

The non-uniformity of a single crystal can sometimes be found in biominerals, where surrounding biomacromolecules are incorporated into the growing crystals. This unique composite structure, combining heterogeneity and long-range ordering, enables the functionalization of single crystals. Polymer gel media are often used to prepare composite single crystals, in which the growing crystals incorporate gel networks and form a bi-continuous interpenetrating structure without any disruption to single crystallinity. Moreover, dyes and many kinds of nanoparticles can be occluded into single crystals under the guidance of gel incorporation. On this basis, the bio-inspired method has been applied in crystal morphology control, crystal dyeing, mechanical reinforcement, and organic bulk heterojunction-based optoelectronics. In this paper, the composite structure, the incorporation mechanisms, and the multiple functions of gel-incorporated single crystals are reviewed. [ABSTRACT FROM AUTHOR]

Fiber-reinforced composites are commonly exposed to environments associated with moisture and solution, resulting in uptake, which causes changes in the bulk resin, the fiber–matrix interface, and even the fiber itself. Knowledge about uptake behavior and diffusion mechanisms and characteristics are critical to better understanding the response of these materials to environmental exposure faced through service to developing better materials through selection of constituents and to the prediction of long-term durability. This paper reviews aspects of uptake mechanisms and subsequent response, as well as models that describe the sorption process, with the aim of providing a comprehensive understanding of moisture-uptake-related phenomena and characteristics such as uptake rate, diffusion and relaxation/deterioration constants, transitions in regimes, and overall response. [ABSTRACT FROM AUTHOR]

The usage of jute/cotton natural composites has surged in almost all fields of engineering due to their advantage of possessing high strength to weight ratio and biodegradability. This paper deals with the fabrication and investigation of mechanical properties of jute/cotton fiber reinforced epoxy composite which is relatively a hybrid composite. In this study, the composite is fabricated by a hand layup process followed by compression molding method with varying the number of layers of composite laminates also with different cutting angles. The composites are prepared with four different proportions of jute/cotton fibers. Various mechanical tests are conducted and the result shows that the 14-layer jute/cotton composite has optimum properties achieved and also observed that 90° has better properties than the others cutting angles. Statistical analysis of composites was done by ANOVA-table; based on mean effective plots, the optimum levels of parameters have been identified, and significant contribution of parameters is determined by analysis of variance Also, failure morphology analysis is done using a scanning electron microscope (SEM) through which the internal structures of the tested specimen are analyzed. [ABSTRACT FROM AUTHOR]

Modified composites, blends, polymers and copolymers are some of those engineered materials which are playing a major and remarkable role in achieving our present sustainable environment. Mechanical, electrical, and biological properties of carbon and native metal nanoparticles are distinctive from others and provide plentiful scaffolds for a wide-range of applications in our lives, including medical devices, pharmaceutical, polymer industry, biomedical field, coating of kitchen appliances, food packaging, clothing, gifts, optical devices, biosensors, antimicrobial objects etc. Distinct chemical and physical properties of silver and carbon-based NPs are considered to act in this way. The antimicrobial and conducting nature of Gr and AgNPs are studied here. There is a vast history of these properties; however, beginners still have a bright future. The antimicrobial activity of these two incorporates antibacterial, antifungal, antiviral, anticancer, antioxidant, antistatic and antibiotic nature. Additionally, both nanomaterials exhibit notable thermal conductivity. Based on these characteristics novel composite/blend materials with enhanced electrical, thermal, antimicrobial, antistatic, and antibiotic effect can be engineered with innovative ideas. This paper expresses the worldwide applications of such nanomaterials. [ABSTRACT FROM AUTHOR]

This paper presents findings from an experiment examining a novel curve-shape sandwich composite made of fiber-reinforced polymer (FRP) facesheets and flexible cores under transverse compressive loading. The curve-shape sandwich composites aim to enhance strength and stiffness while minimizing material use, particularly as liner for rehabilitation of large buried infrastructure like pipes and culverts. The study involved fabricating and testing 24 circular liners with various facesheet–core combinations. Results include deflection measurements, load data, and tensile strain values at different points on the liners. The stiffness of each sandwich specimen was compared to theoretical predictions based on composite facesheet behavior. Notably, bulkermat cores demonstrated superior stiffness and strength compared to three-dimensional (3D) woven fabric cores, exhibiting higher composite action. In contrast, solid-wall liners exhibited greater deformations than sandwich liners. To predict these significant deformations, an iterative analytical model was developed, accounting for geometric nonlinearity. This model accurately predicted test data prior to any material nonlinearity, such as facesheet or core failure. Additionally, the model was used to perform a parametric analysis, exploring various liner characteristics, including diameter, FRP layers, core thickness, and liner shape. [ABSTRACT FROM AUTHOR]

In this paper, a failure analysis of the TMT90m + composite wind turbine blade performed by combining numerical simulation and full-scale destruction tests is presented. The complex failure characteristics of the skin were studied in detail and a driving relationship was obtained. From the results, it was found that the stress concentration leading to local buckling was due to the geometric and layup nonlinearities of the destruction region. This in turn contributed to the successive occurrence of matrix failure and fiber failure. Further, by using the method of finite element secondary development, the accuracy of four commonly used failure criteria for wind blade failure prediction is discussed. From the results, it was found that the Chang-Chang model has ideal prediction accuracy and is more suitable for engineering applications in blade structure design. [ABSTRACT FROM AUTHOR]

With the development and depletion of shallow coal resources, deep coal mining has gradually become normalized. In the face of increasingly severe corrosion environment of coal mining, it is urgent to develop new materials with excellent corrosion resistance for key parts of coal mining equipment. In this paper, SiC, Al2O3 and SiO2 were used as raw materials to prepare three-dimensional network configuration SiC ceramics by organic foam impregnation method. Then the three-dimensional network configuration SiC-Fe composite was prepared by atmospheric pressure casting process. And by electrochemical test, static immersion corrosion test, scanning electron microscope and first-principles simulation calculation, the corrosion resistance of three-dimensional network configuration SiC-Fe composite in harsh mine water environment was characterized, meanwhile the corrosion resistance mechanism was analyzed. The results show that the corrosion potential increases from - 495.756 mV to -379.626 mV, and the corrosion current density decreases from 3.6864 μA/cm2 to 2.1709 μA/cm2 when the SiC ceramic reinforcement is added. The inhibition efficiency based on polarization curve measurement is increased by 41.11%. The charge transfer resistance increases from 5417 Ω·cm2 to 6437 Ω·cm2, and the capacitance value drops from 159.96 μF·cm−2 to 90.12 μF·cm−2. The inhibition efficiency based on electrochemical impedance spectroscopy is increased by 18.83%. First principles calculations show that the addition of SiC reinforcement showed a greater resistance in preventing the migration of corrosive media to the surface of the Fe substrate and can effectively slow down corrosion, which was consistent with the experimental results. [ABSTRACT FROM AUTHOR]

Solidification processing of aluminum graphene composite is an attractive option for synthesis of metal matrix composites. Graphene reinforced aluminum metal matrix composites (GAMMCs) are of interest due to the low density and ultrahigh physical and mechanical properties of Graphene which can improve the properties of Al-Graphene composites. However, solidification processing of aluminum graphene composites has served challenges, including agglomeration of reinforcement and porosity resulting in decrease in properties above 0.five to three wt% graphene. Also, the graphene surface can react with molten aluminum alloys to form aluminum carbide. Challenges with particle distribution and porosity are frequently caused by the poor wetting of reinforcement by melt, requiring additions of selected wetting agents. The other problems include movement of reinforcement within the melt due to density differences and convection leading to nonuniform distribution of reinforcements. The graphene reinforcements can be pushed by solidifying interfaces under certain conditions during solidification leading to segregation of reinforcements in the interdendritic regions. The paper critically analyzes the above problems related to solidification processing of Aluminum-Graphene composites which has not been done in previous publications aluminumgraphene composites. The objective of this paper is to examine the challenges, and suggest possible solutions including addition of elements like silicon and magnesium to aluminum melt, coating graphene with metals like nickel and copper, controlling rate of advancement and nature of advancing solid liquid interface in a manner that they engulf graphene with dendrites or grains. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis and characterization of graphene–polymer composites, focusing on their mechanical and antibacterial properties. Graphene flakes were obtained via an electrochemical method and integrated into polyamide 6 (PA6) matrices using melt intercalation. Various characterization techniques confirmed the quality of the graphene flakes, including X-ray diffraction (XRD), Raman spectroscopy, and infrared (IR) spectroscopy, as well as scanning and transmission electron microscopy (SEM and TEM) imaging. Mechanical tests showed an increase in the elastic modulus with graphene incorporation, while the impact strength decreased. The SEM analysis highlighted the dispersion of the graphene flakes within the composites and their impact on fracture behavior. Antimicrobial tests demonstrated significant antibacterial properties of the composites, attributed to both oxidative stress and mechanical damage induced by the graphene flakes. The results suggest promising applications for graphene–polymer composites in advanced antimicrobial materials. [ABSTRACT FROM AUTHOR]

The conventional manufacturing chain for technical ceramics is too expensive for the production of small series or unique parts with complex designs. Hybrid machines that combine additive and subtractive processes can be an interesting solution to overcome this technology lock-in. However, despite the great interest in hybrid machines for metallic parts, there is a lack of data in the literature when it comes to ceramics. The purpose of this paper is to contribute to closing this gap. It is the first to evaluate the achievable geometrical tolerances according to ISO 2768-2 as well as the surface textures of composite zirconia parts shaped sequentially by pellet additive manufacturing (PAM, from ceramic injection molding feedstock) and finish milling. The green parts were then debinded and sintered to analyze the influence of these steps. Compared to the initial green parts, the sintered parts exhibited shiny and smooth surfaces with sharp edges. Flatness, parallelism and perpendicularity all achieved an H (fine) class, while the surface textures were significantly improved, resulting in arithmetic roughness (Ra) below 1.6 µm. [ABSTRACT FROM AUTHOR]

The abalone shell, a composite material whose cross-section is composed of inorganic and organic layers, has high strength and toughness. Inspired by the abalone shell, several multi-layer composite plates with different layer sequences and thicknesses are studied as bullet-proof material in this paper. To investigate the ballistic performance of this multi-layer structure, the complete characterization model and related material parameters of large deformation, failure and fracture ofAl2O3 ceramics andCarbon Fiber Reinforced Polymer (CFRP) are studied. Then, 3D finite element models of the proposed composite plates with different layer sequences and thicknesses impacted by a 12.7 mm armor-piercing incendiary (API) are built using Abaqus to predict failure. The simulation results show that the CFRP/Al2O3 ceramic/Ultrahigh Molecular Weight Polyethylene (UHMWPE)/CFRP (1 mm/4 mm/4 mm/1 mm) composite is the optimized stack of layers. The simulation results under specified layer sequence and thickness have a reasonable correlation with the experimental results and reflect the failure and fracture of the multi-layer composite protective armor. [ABSTRACT FROM AUTHOR]

This paper presents experimental results from three-point bending tests for a composite made of quadriaxial glass fiber fabrics and an epoxy resin. Two composites were tested, one with 8 layers and the other with 16 layers; both had the same matrix (the epoxy resin). Tests were carried out, using five different test rates from 10 mm/min to 1000 mm/min. The following parameters were recorded and calculated: Young's modulus, flexural stress, flexural strain, energy, force, and all four for the first peak. The experimental data reveal no sensitivity for these materials based on the test rates, at least for the analyzed range; but, the characteristics for the thicker composite, with 16 layers of fabric, are slightly lower than those for the thinner composite, with 8 layers. The results pointed out that, for the same thickness of composite, certain characteristics, such as stress at the first peak, the flexural modulus, strain at the first peak, and energy at the first peak, are not sensitive to the test rate in the range 10–1000 mm/min. The energy at the first peak is double for the 16-layer composite compared to the 8-layer composite, but the specific energy (as energy on cross-sectional area) has close values: 103.47 kJ/m2 for the 8-layer composite and 106.51 kJ/m2 for the 16-layer composite. The results recommend this composite for applications in components with resistance to bending or for low-velocity impact protection. [ABSTRACT FROM AUTHOR]

This paper presents the results of the experimental research on diamond-reinforced composites with WC–Co matrices enhanced with a ZrO2 additive. The samples were prepared using a modified spark plasma sintering method with a directly applied alternating current. The structure and performance of the basic composite 94 wt.%WC–6 wt.%Co was compared with the ones with ZrO2 added in proportions up to 10 wt.%. It was demonstrated that an increase in zirconia content contributed to the intense refinement of the phase components. The composite 25 wt.%Cdiamond–70.5 wt.%WC–4.5 wt.%Co consisted of a hexagonal WC phase with lattice parameters a = 0.2906 nm and c = 0.2837 nm, a cubic phase (a = 1.1112 nm), hexagonal graphite phase (a = 0.2464 nm, c = 0.6711 nm), as well as diamond grits. After the addition of zirconia nanopowder, the sintered composite contained structural WC and Co3W3C phases, amorphous carbon, tetragonal phase t-ZrO2 (a = 0.36019 nm, c = 0.5174 nm), and diamond grits—these structural changes, after an addition of 6 wt.% ZrO2 contributed to an increase in the fracture toughness by more than 20%, up to KIc = 16.9 ± 0.76 MPa·m0.5, with a negligible decrease in the hardness. Moreover, the composite exhibited an alteration of the destruction mechanism after the addition of zirconia, as well as enhanced forces holding the diamond grits in the matrix. [ABSTRACT FROM AUTHOR]

Flexible sensors are prone to the problems of slow recovery rate and large residual strain in practical use. In this paper, a polyurethane functional composite with a gradient change in elastic modulus is proposed as a flexible sensor to meet the recovery rate and residual strain without affecting the motion. Different hard and soft segment ratios are used to synthesize a gradient polyurethane structure. The conductive percolation threshold was obtained between 45 wt% and 50 wt% of flake silver powder. Both gradient polyurethane and gradient polyurethane composites demonstrated that gradient materials can increase the recovery rate and reduce residual strain. The gradient polyurethane composites had a tensile strength of 3.26 MPa, an elastic modulus of 2.58 MPa, an elongation at break of 245%, a sensitivity coefficient of 1.20 at 0–25% deformation, a sensitivity coefficient of 11.38 at 25–75% deformation, a rate of recovery of 1.95 s at a time, and a resistance to fatigue (over 1000 cycles at a fixed strain of 20% showed a stable electrical response). The sensing performance under different cyclic strain frequencies was also investigated. The process has practical applications in the field of wearable skin motion and health monitoring. [ABSTRACT FROM AUTHOR]

Copyright of Association of Arab Universities Journal of Engineering Sciences (JAARU) is the property of Association of Arab Universities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper attempts to analyze the random fatigue life and failure modes of joints using two calculation methods. Three kinds of tests were carried out, which were the static test, constant amplitude fatigue test and the random fatigue test, and four kinds of joints were designed. After the static test, the joint was subjected to a constant amplitude fatigue test by selecting different percentages of load according to the static strength. In order to predict the random fatigue life more precisely, two calculation methods were carried out, which were the linear cumulative damage method and the equivalent loading finite element method. Based on the linear cumulative damage hypothesis, the fatigue life of the joint was established as a function of the load amplitude, and then, the random life prediction was calculated by the amplitude distribution of the random loading. Another method was the equivalent loading method, which was to obtain the equivalent constant amplitude fatigue loading of the random loading spectrum. The finite element model was established based on the stiffness and strength degradation rule. The equivalent random life and fatigue failure modes of the joint were modeled. The two life prediction methods show good agreement with the fatigue experimental result, and all prediction results were included in a scatter band of the factor of 2. [ABSTRACT FROM AUTHOR]

Vinyl esters are increasingly being used as the matrix polymer in fibre-reinforced composites for demanding large applications which experience long-term exposure to moist and wet conditions. This paper presents the results of a study of ageing due to moisture absorption in vinyl ester polymer and glass fibre–vinyl ester laminates. The moisture uptake kinetics of the two neat VE polymers, cured at different conditions, and their glass-reinforced composites has been characterised by gravimetric methods. These studies have been carried out using submersion in water at 23 °C and 50 °C and exposure to high relative humidity moisture conditions at room temperature. A dynamic mechanical analysis characterisation of the glass transition temperatures of both the aged matrix and the composite is also presented. [ABSTRACT FROM AUTHOR]

This paper systematically investigates the effective parameter on the performance of polydimethylsiloxane/graphene (PDMS@Gr)-based triboelectric nanogenerators (TENGs) as well as their applications. PDMS@Gr films containing 0, 0.05, 0.5, 1, and 1.5 wt.% graphene are synthesized, and their surface characteristics, mechanical behavior, and electrical properties are characterized. Vertical contact-separation mode TENGs are fabricated, and their performance is evaluated. The results demonstrate that the surface roughness and surface charge density are the most critical parameters for the performance of PDMS@Gr-based TENGs compared to the electrical and mechanical properties of the friction layers. The PDMS@Gr-based TENG with 1 wt.% graphene shows the highest power output of 2.6 W/m2 at an optimized working condition (5 Hz and 15 N). It also exhibits stable power output until 15,000 working cycles and displays battery-free applications by powering a light-emitting diode (LED) array, a calculator, a digital watch, and a digital thermometer. [ABSTRACT FROM AUTHOR]

In this paper, a series of alumina/waterborne polyurethane composites was prepared, and the effects of different amounts of alumina on the thermal conductivity and insulation properties of the composites were studied. In addition, alumina/graphene/waterborne polyurethane composites were prepared by co-doping graphene and alumina into waterborne polyurethane to improve the heat conduction path. The synergistic effect between different fillers formed a denser heat conduction network. The added amount of alumina is 60 wt%. When the amount of graphene added is 2 wt%, the thermal conductivity of the composite can reach 1.049 W/(m·K), which is twice that of the alumina-filled composite, which is obviously better than that of the single-filler filling. Compared with the system only adding alumina, it seeks to improve thermal conductivity while maintaining good insulation. The results show that it is an effective way to improve the thermal conductivity and insulation properties of materials when different fillers are compounded. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Chemistry is the property of Chinese Journal of Applied Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Mechanics is the property of Chinese Journal of Applied Mechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a titanium dioxide/covalent organic framework (TiO2/COF) composite was prepared and its photocatalytic removal of dye was investigated. Using tetrabutyl titanate as a titanium source, TiO2 nanomaterial was prepared by sol‐gel method. In the presence of TiO2, TiO2/COF core‐shell composite was prepared by solvothermal synthesis using melamine and 1,4‐phthalaldehyde as ligands. The prepared materials are characterized by SEM, TEM, XPS, XRD, TG, FTIR, BET, EPR, PL, and UV‐Vis‐DRS techniques. Using malachite green as a model of dye wastewater, the photocatalytic degradation performance of TiO2/COF composites was investigated under the irradiation of ultraviolet light. The results show that the modification of COF significantly improves the photocatalytic efficiency of TiO2, the degradation rate increases from 69.77 % to 93.64 %, and the reaction rate constant of the first‐order kinetic equation is increased from 0.0078 min−1 to 0.0192 min−1. Based on the free radical capture experiment, the photocatalytic degradation mechanism of TiO2/COF was discussed, and the feasibility of its photocatalytic degradation of malachite green was theoretically clarified. Accordingly, a simple and practical method for photocatalytic degradation of malachite green was constructed, which has potential application value in the degradation of dye wastewater. [ABSTRACT FROM AUTHOR]

The tack of prepreg is a key factor affecting the automatic tape laying process. During the manufacturing process of large composite parts, prepreg material may be stored at room temperature for several days, resulting in a decrease in its tack. In this study, a new tack test tool was designed, and the decay rate of prepreg tack at different temperatures was tested. We proposed a prepreg tack decay model, which assumes that the main factor in tack decay is the reduction in resin chain activity during storage. The maximum deviation between the model calculation results and the experimental results of the tack decay rate is 9.7%. This study also proposed a new statistical unit for prepreg tack, which can establish the relationship between the tack of prepreg and its remaining storage time and reduce prepreg management costs. [ABSTRACT FROM AUTHOR]

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The bumper is an automotive part act as a protective shield in the vehicle. It bears and absorbs the load when the vehicle incurs a collision. If the bumper has got more weight it leads to more fuel consumption and decreases the fuel efficiency of the vehicle. This problem can be overcome by reducing the weight of the bumper without compromising its performance. The main objective in bumper design and fabrication is that it should possess less weight and at the same time, it should withstand the higher load during a collision. In this paper, the properties and performance of the developed bumper composite are compared with the existing bumper. The bumper performance is optimized using a finite element analysis with ANSYS R15.0. From the cost analysis, it has been observed that the weight and cost of the Basalt composite bumper is 49% and 56% lesser than the steel bumper. The Impact strength and Factor of Safety values of the Basalt fabric composite bumper is 47.6% and 32.5% higher than the steel bumper. The total deformation of the Steel bumper is 15.7 mm, and the Basalt composite bumper is 32 mm, which shows 51% higher deformation than steel. [ABSTRACT FROM AUTHOR]

This study uses an incipient wet impregnation method to look into the structural and dielectric properties of Bentonite that have been changed by adding different amounts of Ce and Zn. X-ray diffraction (XRD) analysis showed that the montmorillonite phase was the most common in Ce- and Zn-doped bentonite. Silicon dioxide (SiO2) and quartz (Q) were also found. Scanning electron microscopy (SEM) demonstrated enhanced platelet aggregation and porous structures in doped compounds. Energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of Si, Al, Na, Ce, Zn, Ca, Mg, Cl, Fe, and K elements. Dielectric analysis, focusing on frequency and temperature dependence, unveiled an inverse relationship between frequency and the dielectric constant. Additionally, a strong correlation between temperature and dielectric properties was established through regression equations, indicating an increase in dielectric constant with temperature. Electric modulus analysis showed dispersion at high frequencies, suggesting charge carrier mobility. The AC conductivity analysis showed that the conductivity consistently decreased as the temperature rose. There were clear frequency-independent plateaus and intrinsic charge carrier relaxation that were seen. A fitting analysis showed that charge carriers hopped and the dielectric relaxed, and adding Ce and Zn made the material less conductive. The novelty of this paper lies in its focus on examining the dielectric characteristics of doped materials based on bentonite, particularly concerning the incorporation of Zn and Ce. Highlights: Investigation of structural and dielectric properties of Bentonite modified with Ce and Zn. Utilization of incipient wet impregnation technique for modification. Enhanced platelet aggregation and porous structures observed in doped compounds via SEM. Dispersion at high frequencies indicated by electric modulus analysis. Decrease in conductivity with rising temperature observed in AC conductivity analysis. Charge carrier hopping, and dielectric relaxation mechanisms identified through fitting analysis. Incorporation of Ce and Zn resulted in reduced conductivity in the materials. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper aims to investigate the mechanical and metallurgical properties of magnesium AZ91 composite. Zinc and Aluminium were selected as reinforcement particles in the Magnesium metal matrix composite. The composites 88.5%Mg-9%Al-1.5%Mn-1%Zn, 87.5%Mg-9%Al-2.5%Mn-1%Zn, 86.5%Mg-9%Al-3.5%Mn-1%Zn, 85.5Mg-9%Al-4.5%Mn-1%Zn, 84.5%Mg-9%Al-5.5%Mn-1%Zn and 83.5%Mg-9%Al-6.5%Mn-1%Zn are prepared through powder metallurgy. The hardness and compressive tests are used to investigate the mechanical properties of the magnesium composite. The results of the mechanical properties indicate that manganese plays a vital role in improving the hardness of the AZ91 composite. The thermogravimetric analysis investigated the weight ratio % at the 400OC. The scanning electron. microscopic analysis was used to investigate the reinforcement particle's bonding level and the defects on the composite. Based on the results, the manganese plays a vital role in improving the mechanical properties of the AZ91 composite. [ABSTRACT FROM AUTHOR]

This paper examines the microstructure evolution and thermal properties of Al/Ti composites with different volume fractions of Ti. The laminated composites were first fabricated by the accumulative roll bonding (ARB) process. The fabricated composites were then stacked and bonded together by cold roll bonding process to produce Ti–Al functionally graded composite. The microstructural investigation of ARBed composites revealed that plastic instabilities including necking and rupture took place within composites. As a result, the fragments of Ti were distributed uniformly across the Al matrix. In addition, the SEM images of the Al–Ti functionally graded composite showed a compositional gradient from the Al side to the Ti side. Based on the EBSD maps taken from Al and Ti layers, the grain refinement was successfully achieved during six passes. Besides, with an increase in the volume fraction of Ti, the grains became finer, indicating the gradient in grain size across Al–Ti functionally graded composite. Furthermore, the experimentally measured thermal properties of Al and Ti sheets increased as a function of temperature while they declined by increasing passes. However, thermal conductivity, thermal diffusivity, coefficient of thermal expansion, and specific heat capacity of Al/Ti composites showed a reduction with the rise of Ti content. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The development of thermal energy storage materials applied in various fields has been attracting considerable attention in recent years. In this paper, a series of 1,6-hexanediol (HDL)/silicon dioxide (SiO2) form-stable composite phase change materials (fs-CPCMs) with various mass percentage of HDL loadings were made through sol–gel technique. For HDL/SiO2 fs-CPCMs, HDL was served as PCM, and silica gel was acted as the supporting matrix to keep a stable state without leakage of the composites even the temperature was over 85 °C. The results from form-stability test and DSC measurements showed that the as-prepared fs-CPCM with the mass fraction of HDL at 70 wt% presented good form-stability, suitable melting point (43.5 °C), and reasonable fusion enthalpy of 130.9 J/g. Fourier transform infrared (FT-IR) spectroscopy indicated that only physical adsorption existed between the HDL and silica gel. Moreover, the thermal performance tests showed that the thermal energy storage and release rates of the as-prepared HDL/SiO2 fs-CPCM was enhanced compared to pure HDL. In summary, the as-prepared fs-CPCMs exhibit reasonable latent heats, good thermal stabilities, and reliability, which are promising candidates for energy-saving construction materials. [ABSTRACT FROM AUTHOR]

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)