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The paper deals with the influence of the brittleness of glass fibers on the selected performance properties of the fibrous polymer composite. Understanding the fatigue behavior of fiber-reinforced plastics is desirable for exploiting their features in safe, durable, and reliable industrial components. Based on the proposed methodology, it is possible to assess the impact of material reuse on selected mechanical and rheological properties. To verify the methodology by experimental analysis, homopolymer PP reinforced with chemically grafted glass fiber (30 wt%) was selected. The proposed methodology was subsequently verified by experimental analysis and evaluated statistically. The morphology of the fracture surfaces was evaluated, and the fiber-polymer matrix adhesion was monitored at the interface of the fracture surfaces. Based on the measured and evaluated values and fracture surfaces, we can say that the brittleness of the fibers significantly affects the performance properties of the tested polymer composite. [ABSTRACT FROM AUTHOR]

Hand layup was used to fabricate the glass fibre reinforced aluminium foam epoxy composites in this study. On the manufactured materials, dry sliding wear experiments were performed. The effect of wearprocess parameters such asapplying load (kg), speed (m/s), and sliding distance (m) on specific wear rate (Ws) was investigatedand the obtained results were compared with neat glass fibre reinforced epoxy composite in this work. The outcome of these results showed that specific wear rate (Ws) of glassfibre epoxy composite containing aluminium foam decreased as compared with neat glass fibre reinforced polymer composites. Experimental results showed that a minimum wear rate of 10.1 µm was attained for the sliding velocity (1.5 m/s), Applied load (2 kg), and sliding distance (1000 m) in the fabricated composite laminates. It was observed thatthe resistance to wear in glass fibre reinforced aluminium foam composite was mainly due to the bond strength between aluminium foam and epoxy. [ABSTRACT FROM AUTHOR]

In this paper, a new type of foldcore sandwich panel (tentatively called X‐type foldcore sandwich panel) is proposed by combining the X‐type corrugated sandwich panel and the Miura‐ori sandwich panel. The experimental specimens are prepared by using a glass fiber‐reinforced polymer. To systematically reveal the low‐velocity response mechanism and impact resistance of sandwich panels, a hemispherical impactor is used to impact panels. The effects of impact energy, impact position, diameter of tup, and impact mass on low‐velocity impact performance of X‐type foldcore sandwich panels are considered. The damage morphology, response process, and failure mechanism are analyzed under different working conditions. The results show that under the impact of 75 and 125 J, the impact resistance of the node is better than that of the base. Under 200 J impact, the impact resistance of the base is better than that of the node. Compared with the traditional foldcore sandwich panel, the new configuration reduces the impact resistance difference between two positions (node and base). Highlights: A new foldcore sandwich panel is proposed.The impact effect of energy, mass, position, and tup diameter is investigated.Damage morphology, response process, and impact resistance are analyzed.The new structure reduces differences in impact resistance. [ABSTRACT FROM AUTHOR]

Glass-fiber-reinforced polymers' (GFRP), as compared to metallic materials, require more intricate machining. The composite construction experiences delamination as a result of this machining operation. Delamination at the exit and entrance of holes drilled is a significant flaw in composite materials. Superior-drilled holes can be produced by optimizing the drilling process's governing factors. This study's goal is to maximize the drilling settings using entropy weight-coupled gray relational analysis with fuzzy logic to account for multiple performance factors. Taguchi's L25 5-level orthogonal array is used to increase the accuracy of the results in this study. Feed rate and spindle speed are considered the control variables, and torque, thrust force, and delamination at both the exit and entry are the responses. The results show that drilling performance is enhanced by lower feed rates and elevated spindle speeds. Additionally, the present findings show that feed rate has a stronger influence on drilling hole quality. These results also proved that increasing the number of levels increases the accuracy of the results. Entropy-based gray relational analysis with fuzzy logic using more levels of factors can be effectively used for the optimization of the drilling process. [ABSTRACT FROM AUTHOR]

This review article gathers the most recent recycling technologies for thermoset and thermoplastic polymers. Results about existing experimental procedures and their effectiveness are presented. For thermoset polymers, the review focuses mainly on fibre-reinforced polymer composites, with an emphasis on epoxy-based systems and carbon/glass fibres as reinforcement, due to the environmental concerns of their end-of-life management. Thermal processes (fluidised bed, pyrolysis) and chemical processes (different types of solvolysis) are discussed. The most recent combined processes (microwave, steam, and ultrasonic assisted techniques) and extraordinary recycling attempts (electrochemical, biological, and with ionic liquids) are analysed. Mechanical recycling that leads to the downgrading of materials is excluded. Insights are also given for the upcycling methodologies that have been implemented until now for the reuse of fibres. As for thermoplastic polymers, the most state-of-the-art recycling approach for the most common polymer matrices is presented, together with the appropriate additivation for matrix upcycling. Mechanical, chemical, and enzymatic recycling processes are described, among others. The use of fibre-reinforced thermoplastic composites is quite new, and thus, the most recent achievements are presented. With all of the above information, this extensive review can serve as a guide for educational purposes, targeting students and technicians in polymers recycling. [ABSTRACT FROM AUTHOR]

Polymers and polymer composites are frequently used in tribological applications. However, their use is often limited by excessive wear or plastic deformation, therefore research and development aiming to improve the materials is ongoing. Tribological evaluations of polymer composites often study the friction coefficient and wear rate for different types, sizes and amounts of fillers. But rarely are any mechanisms presented. Although polymer materials differ from metals, the techniques typically used for metal components, for example, scanning electron microscopy (SEM) and energy dispersive x‐ray spectroscopy (EDS), can be adapted to polymer materials, to achieve more informative SEM micrographs and EDS analyses. The aim of this article is to present useful analysis strategies, from sample preparation and selection of viewing angles, to selection of instrument settings and detector types. The strategies are exemplified by analysis of poly‐phenylene‐sulphide filled with glass fiber, evaluated against steel in a reciprocating ball‐on‐flat test set‐up. This article takes its starting point with the worn surfaces, and subsequently analyze them using SEM and EDS. A selection of cross section preparation techniques, analysis parameters and microscopy settings are presented and discussed. By combining these techniques and settings, the observation of a strongly modified surface layer, as well as sub‐surface plastic deformation and imbedded wear particles, is facilitated. [ABSTRACT FROM AUTHOR]

This study investigates the shear failure characteristics of reinforced concrete (RC) beams retrofitted with Glass Fiber Reinforced Polymer (GFRP) sheets. Fifteen RC beams were initially tested for shear capacity and then retrofitted using various GFRP wrapping techniques, including full wrapping, U-shaped wrapping, side wrapping, vertical alignment, and 45-degree inclined wrapping. The results revealed significant enhancements in shear capacity, with vertical alignment wrapping showing the highest increase. The study concludes that GFRP wrapping is an effective and economical method for retrofitting shear-deficient RC beams, contributing to improved structural safety. [ABSTRACT FROM AUTHOR]

This paper focuses on the shear behavior of reinforced concrete (RC) beams strengthened with carbon–glass-fiber-reinforced polymer (C-GFRP) plates under different anchoring schemes. The study consisted of four reinforced specimens: specimen CS-1 with no reinforcement and three groups of reinforced specimens SR-1, SR-2 and SR-3. The studies used a four-point bending test to evaluate the reinforcement effect of mechanically anchoring C-GFRP plates. The results of the analysis of load–deflection, strain and bearing capacity indicated that a better reinforcement effect was observed with fiber-reinforced polymer. The test results suggested that the occurrence time of critical oblique cracks was delayed and the development speed of critical oblique cracks was limited by mechanically anchoring the C-GFRP plates. C-GFRP plates significantly increased the stiffness of the reinforced specimen and reflected the superiority of mechanical anchoring. The ultimate shear capacity of the mechanically anchored C-GFRP plates has been significantly improved. With a reasonable increase in the amount of C-GFRP plate, the shear resistance of the test beam became stronger. Compared with the CS-1 specimen without reinforcement, the yield load values of the reinforced specimens SR-1, SR-2 and SR-3 increased by 5.56%, 18.80% and 26.50%, respectively. The ultimate load of reinforced specimens SR-1, SR- 2 and SR-3 increased by 11.64%, 17.47% and 31.51%, respectively. The researchers deduced their theoretical calculation method from the bearing capacity of RC beams strengthened by anchoring with carbon–glass-fiber-reinforced polymer plates. The test findings were in good accord with the theoretical calculation model of bearing capacity suggested in this research. [ABSTRACT FROM AUTHOR]

This paper presents the details of experimental testing for the suitability of glass fibre-reinforced polymer (GFRP) pipes for gas transmission lines. Hydrostatic bursting pressure and split ring tests were performed on 150 mm (6 in.) and 250 mm (10 in.) diameter pipes made by both the pultruded and filament wound processes. The filament wound pipes were tested to evaluate the butt joint failure strengths. The classical lamination theory (CLT) was used to predict the elastic behaviour of these pipes. It was found that filament wound pipes offer superior resistance to internal pressures compared to pultruded pipes. Furthermore, the joints were found to be the most limiting component in terms of pipeline burst pressure capacity. The observed elastic behaviour by the employed hydrostatic pressure test method showed strong agreement with the CLT predictions which confirms its applicability for testing GFRP pipes for bursting pressure. Failure predictions between the experimental data and theory had minor discrepancies. [ABSTRACT FROM AUTHOR]

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Resin pre-coating technology is widely used in all aspects of composite materials, especially in the repair of composite materials. The pre-coating is formed by combining acetone with the resin, which is diffused and cured by the epoxy adhesive at the same time. It acts as an interlock to prevent the interface from debonding and to fill in the damaged cracks. The capillary action of acetone allows the resin to permeate the cracks in the fiber damage layers, thus filling the cracks and completing the repair. The pre-coating solutions of 10 wt%, 20 wt%, 25 wt%, 35 wt%, and 45 wt% resin were applied to damaged areas respectively, and cured at 60°C for 7 days. The crack filling effect was observed by scanning electronic microscopy (SEM). At the same concentration, the effect of prolonged repair time was also studied. The other two repair times were 14 days and 30 days respectively. In addition, the tensile properties of the materials before and after repair were tested and compared. The results showed that 25 wt% resin pre-coating had the best repair performance after 7 days, with a repair rate of 27%, which was 22% higher than the conventional repair without resin pre-coating. However, the repair effect became more obvious after the extension of repair time, and the repair effect of 25 wt% resin pre-coating reached 44% after 30 days curing. Therefore, it was found that the resin can fully penetrate the cracks in the damaged area with resin pre-coating technology, and 25 wt% resin pre-coating solution is the best choice. [ABSTRACT FROM AUTHOR]

The fibre–matrix interface represents a vital element in the development and characterisation of fibre-reinforced polymers (FRPs). Extensive ranges of interfacial properties exist for different composite systems, measured with various interface characterisation techniques. However, the discrepancies in interfacial properties of similar fibre–matrix systems have not been fully addressed or explained. In this review, first, the interface-forming mechanisms of FRPs are established. Following a discourse on three primary factors that affect the fibre–matrix interface, the four main interface characterisation methods (single-fibre fragmentation, single-fibre pull-out, microbond and fibre push-in/-out tests) are described and critically reviewed. These sections review various detailed data reduction schemes, numerical approaches, accompanying challenges and sources of reported scatter. Finally, following the assessment of several infrequent test methods, comprehensive conclusions, prospective directions and intriguing extensions to the field are provided. [ABSTRACT FROM AUTHOR]

The paper presents a fully three-dimensional coupled simulation of flame propagation through epoxy resins reinforced with glass fiber (glass–epoxy) under the action of a heat flux from two sides, using the Fire Dynamic Simulator package. The model includes three-dimensional heat and mass transfer, diffusion of basic substances in the gas phase, and diffusion transport of pyrolysis products in the solid phase. The pyrolysis and oxidation processes are represented by macroreactions and take into account the effect of the phosphorus-containing flame retardant DDM-DOPO. The model satisfactorily predicts the experimentally observed dynamics of flame propagation. [ABSTRACT FROM AUTHOR]

In this study, the suitability of waste from glass fibre production as a secondary filler for a polymeric durable hydrophobic coating, based on an innovative polyurethane organic–mineral base, was experimentally verified. The main aim of this work was to develop a basic formulation for a polymeric hydrophobic coating designed primarily for usage in aggressive environments. For this purpose, a total of four formulations were tested with different weight percentages of waste glass fibre, i.e., from 30 to 60%. The basic properties in the fresh state, such as the coating workability and kinematic and dynamic viscosity, were verified, and an application test was performed. The formulations were also verified after the polymerisation of the coating. Adhesion on a concrete substrate and the tensile properties and hardness of the coating were tested. Chemical resistance to liquid aggressive media and the microstructure of the coating after exposure to SO2 were also tested, as these are critical properties. All the formulations showed better workability than the reference coating without a filler, and the formulation with the highest filling (60%) appeared to be optimal. The maximum adhesion on the concrete substrate (11.9 MPa) and tensile strength (21.6 MPa) were recorded for the formulation with 60% waste fibreglass. It can be concluded that with an increase in the waste glass content, there was a significant improvement in the properties of the coatings. Additionally, the waste fibreglass did not have a significant negative impact on chemical resistance. [ABSTRACT FROM AUTHOR]

Strengthening and repairing infrastructure with fiber‐reinforced polymers while achieving low‐cost, real‐time monitoring of cracks in engineering structures is highly challenging. Herein, a piezoelectric glass‐fiber‐reinforced polymer (piezo‐GFRP) sensor is used to monitor the mechanical behavior of cement beams with cracks under cyclic bending. The output voltage and frequency of the sensor are shown to be effective feedback signals for determining the mechanical behavior. The thin piezo‐GFRP sensor shows sufficient piezoelectric sensitivity to monitor the slight variations in the mechanical behavior of the cement beams during the early stages of cracking. It is indicated in this result that such sensors have the potential for the multifunctional structural health monitoring of engineering structures. [ABSTRACT FROM AUTHOR]

Polyamide polymers are widely used in tribological areas in a wide range of industries. The purpose of this study is to extend the tribological life of this material. For this purpose, composite materials were produced by adding solid lubricants such as graphite and wax to the polyamide 6 (PA6) matrix at different rates, and the synergistic effect of these composites on tribological behavior was investigated. Tribological experiments were carried out under dry sliding conditions and on themselves. The polyamide 6/graphite/wax composites were first produced in the form of granules in a twin‐screw extruder, and then test samples were molded using the injection molding technique. Wear tests were performed using a pin‐on‐disc wear device. Tribological tests were carried out at a sliding speed of 0.5 m s−1 and under loads ranging from 10 N to 250 N. Following the experiments, the friction coefficient, specific wear rate, and surface wear were determined under the condition of the materials working on each other. The results showed that the lowest specific wear rate and friction coefficient were obtained for the polyamide 6 composites containing 6 % wax and 15 % glass fiber working on each other. [ABSTRACT FROM AUTHOR]

The durability of short fiber reinforced polymers (SFRPs) is affected by several variables. Accurate unifying fatigue parameters are thus essential for an efficient characterization campaign. This research investigated the fatigue behavior of a Polyphtalamide PA6T/6I reinforced with 50% of glass fibers. Two thicknesses (1.6 and 3 mm), two orientations from the injection molding direction (0° and 90°), and three load rations (−0.5, 0.1, 0.5) were investigated. A new fatigue parameter, called alternating energy density (AED), was presented; its ability to correlate the fatigue tests results was compared to other known fatigue parameters—cyclic mean strain rate and cyclic creep energy density. All the fatigue parameters were found to be independent of specimen thickness. Furthermore, the prediction of the fatigue lifetime based on AED showed greater accuracy with respect to the other known investigated methods. AED could thus be used for accurate and efficient lifetime prediction of SFRPs. Highlights: A new unifying fatigue parameter for SFRPs called AED is proposed.AED proved higher unifying capabilities than other known methods.A new SFRP fatigue database including thickness, orientation, and load ratio is provided. [ABSTRACT FROM AUTHOR]

The recent advancement towards THz system design and development, THz spectroscopy and non-destructive testing (NDT) fascinates researchers' attention in the development of absorbing coating and composites to counter stealth technologies and shielding from THz radiation. Conductive fillers based THz absorber composites have emerged as a solution as their properties can be tuned with the change in the filler loading. In this study, several multilayer composites are prepared by wet lay-up process using conducting fillers-chopped carbon fibre (CCF), milled carbon fibre and carbon veil (CV) in epoxy matrix with glass fibre as reinforcement. These composite samples were evaluated for absorption in 0.1–2.5 THz frequency domain to explore their use for THz absorber applications. The results show that the absorption performance of fabricated composite structures is significantly affected by the type of filler, percentage loading of filler and frequency range. The polymer composite with CV filler exhibits maximum 99% absorption (10–20 dB reflection loss) in the frequency range of 0.5–2.25 THz. Considering the high mechanical strength and broadband absorption of THz radiations, these composites may provide a better substitute for fragile wideband THz absorptive coatings as well as metamaterials based narrowband THz absorbers. [ABSTRACT FROM AUTHOR]

Lightweighting of automotives is crucial for the decrease of fuel and energy consumption, as well as CO2 emission and environmental pollution. Polymer composites, especially the high strength glass fiber/polyamide (GF/PA) composites, have great potential in lightweight; however, they have not been universally accepted due to their insufficient performance. Here, a stearate‐ended hyperbranched polyester (HBP‐12‐n) is designed and high‐performance GF/PA6 composites with high GF content are prepared. The flowability of the composites can be further increased by combining carboxyl‐ended hyperbranched polymer (HyPer C181) with HBP‐12‐n. Compared with unmodified GF/PA6 composites, the melt flow index (MFI) can be increased remarkably to 587% by adding a 0.7 wt% mixture of HBP‐12‐75 and HyPer C181, and the strength and toughness remain competitive. The simultaneous improvement in MFI and impact strength of GF/PA6 composites is the first discovery of this kind, and a synergistic mechanism of amphiphilic bridging‐deformation slipping‐interfacial strengthening of hyperbranched polymers is proposed to account for this phenomenon. This work provides a simple strategy to fabricate GF/PA6 composites with the extensive application for automotive parts and has great prospects in making automotives lightweight and reduction of CO2 emissions. [ABSTRACT FROM AUTHOR]

In this study, a series of experiments and finite element analyses were conducted to investigate the effects of glass fiber sheet (GFS) lamination on the strength of pin-bearing single-bolted pultruded glass-fiber-reinforced polymer (PGFRP) connections. In the experiments, nine types of GFS lamination were molded using the vacuum-assisted resin transfer molding method (VaRTM) and bonded onto the surfaces of PGFRP members. Then, four different end distances of PGFRP plates to bolt diameters (e / d) were surveyed, ranging from 3 to 6. The results indicated that all types of GFS lamination offered excellent improvement effects for the ultimate loads of the PGFRP connections. The strengthening effects were better when the connections had smaller e / d values. In addition, external 0°/90° GFSs provided the best performance for GFS-strengthened PGFRP connections with medium e / d values. Finally, it was demonstrated that finite element analysis (FEA) could be a useful method for predicting the failure loads of GFS-strengthened PGFRP connections. [ABSTRACT FROM AUTHOR]

The milling of polymer composites is a process that ensures dimensional and shape accuracy and appropriate surface quality. The shaping of thin-walled elements is a challenge owing to their deformation. This article presents the results of milling polymer composites made of glass and carbon fibers saturated with epoxy resin. The milling of each material was conducted using different tools (tools with polycrystalline diamond inserts, physically coated carbide inserts with titanium nitride and uncoated carbide inserts) to show differences in feed force and deformation after the machining of individual thin-walled samples. In addition, the study used recurrence analysis to determine the most appropriate quantifications sensitive to changes occurring in milling different materials with the use of different tools. The study showed that the highest forces occurred in milling thin-walled carbon-fiber-reinforced plastics using uncoated tools and the highest feeds per revolution and cutting speeds. The use of a high feed per revolution (0.8 mm/rev) in carbon-fiber-reinforced plastics machining by uncoated tools resulted in a maximum feed force of 1185 N. A cutting speed of 400 m/min resulted in a force of 754 N. The largest permanent deformation occurred in the milling of glass-fiber-reinforced composite samples with uncoated tools. The permanent deformation value of this material was 0.88 mm. Low feed per revolution (0.1 mm/rev) resulted in permanent deformations of less than 0.30 mm for both types of materials. A change in feed per revolution had the most significant effect on the deformations of thin-walled polymer composites. The analysis of forces and deformation made it possible to conclude that high feed per revolution were not recommended in composite milling. In addition to the analysis of machining thin-walled composites, the novelty of this study was also the use of recurrence methods. Recurrence methods were used to determine the most appropriate quantifications. Determinism, averaged diagonal length and entropy have been shown to be suitable quantifications for determining the type of machined material and the tools used. [ABSTRACT FROM AUTHOR]

The work is aimed at studying the impact resistance of epoxy oligomer matrices (EO) modified with polysulfone (PSU) or polyethersulfone (PES) and glass fibers reinforced plastics (GFRP) based on them under low-velocity impact conditions. The concentration dependences of strength and fracture energy of modified matrices and GFRP were determined. It has been determined that the type of concentration curves of the fracture energy of GFRP depends on the concentration and type of the modifying polymer. It is shown that strength σ and fracture energy EM of thermoplastic-modified epoxy matrices change little in the concentration range from 0 to 15 wt.%. However, even with the introduction of 20 wt.% PSU into EO, the strength increases from 164 MPa to 200 MPa, and the fracture energy from 32 kJ/m2 to 39 kJ/m2. The effect of increasing the strength and fracture energy of modified matrices is retained in GFRP. The maximum increase in shear strength (from 72 MPa to 87 MPa) is observed for GFRP based on the EO + 15 wt.% PSU matrix. For GFRP based on EO + 20 wt.% PES, the shear strength is reduced to 69 MPa. The opposite effect is observed for the EO + 20 wt.% PES matrix, where the strength value decreases from 164 MPa to 75 MPa, and the energy decreases from 32 kJ/m2 to 10 kJ/m2. The reference value for the fracture energy of GFRP 615 is 741 kJ/m2. The maximum fracture energy for GFRP is based on EO + 20 wt.% PSU increases to 832 kJ/m2 for GFRP based on EO + 20 wt.% PES—up to 950 kJ/m2. The study of the morphology of the fracture surfaces of matrices and GFRP confirmed the dependence of impact characteristics on the microstructure of the modified matrices and the degree of involvement in the process of crack formation. The greatest effect is achieved for matrices with a phase structure "thermoplastic matrix-epoxy dispersion." Correlations between the fracture energy and strength of EO + PES matrices and GFRP have been established. [ABSTRACT FROM AUTHOR]

Polymer composites are widely used in various fields and industries. This study investigated milling of four different glass and carbon fiber reinforced plastics. First, feed force values were determined in the milling process conducted using tools with polycrystalline diamond inserts, with titanium nitride-coated cemented carbide inserts and with uncoated ground cemented carbide inserts. Machined surfaces were then examined for roughness. Using scanning microscopy (SEM), differences in the surface layer were also determined. Results showed that the lowest force values were obtained in milling of glass fiber reinforced plastics using tools with polycrystalline diamond inserts. The best machining results in terms of roughness were obtained after milling glass fiber reinforced plastics. [ABSTRACT FROM AUTHOR]

The intention of this research is to recapitulate the two different fillers like E glass fiber and nanocarbon fiber, which were utilized to fabricate the polymer matrix composites by the assistance of epoxy resin. The mechanical compression molding was influenced to produce the polymer-based nanocomposites under consideration of optimal process parameters. There are three different weight fractions E glass fiber (40%, 45%, and 50%), nanocarbon fiber (10%, 15%, and 20%), and epoxy concentrations (30%, 40%, and 50%), respectively, that were used to produce the polymer matrix composites. Those processing parameters were designed by the L9 Taguchi with DOE technique to conduct the mechanical tests like tensile strength and hardness properties. The signal-to-noise ratios were successfully accomplished to identify optimal process parameters for improving the individual responses. The ANOVA and interaction was additional supports to enhance the mechanical properties. The scanning electron microscope was used to examine the fracture surfaces at the tensile fracture specimens with optimal conditions. Moreover, the maximum mechanical characteristics were attained by the increasing of nanocarbon fiber in the processed polymer matrix composites. [ABSTRACT FROM AUTHOR]

In order to study the influence of vinyl acetate–ethylene copolymerization emulsions on the bonding performance of fiber and mortar, mortar materials with different polymer contents were prepared. The optimal mix ratio of the matrix was obtained using a pull-out test with a 0° inclination angle. On this basis, polypropylene fibers and alkali-resistant glass fibers were set at different burial depths (6 mm, 12 mm, and 18 mm) and different burial angles (0°, 30°, 45°, and 60°). The load–displacement curves of two types of fibers pulled out from the polymer mortar were obtained. The test results show that polymer contents of 3% and 5% increase the peak pull-out loads of glass fibers and polypropylene fibers by 16.28% and 30.72% and 7.41% and 27.11%, respectively. When the polymer content is 7%, the peak pull-out load decreases by 1.31% and 24.26%, especially for polypropylene fiber, which significantly weakens the bonding performance between the matrix and the fiber. The pull-out load of glass fibers and polypropylene fibers increases with the increase in the buried depth, and both show tensile failure at 18 mm. As the embedding angle increases, the pull-out load of polypropylene fibers decreases continuously, while the glass fiber shows a higher pull-out load at 30°. [ABSTRACT FROM AUTHOR]

Recently, fiber-reinforced, epoxy-based, optically transparent composites were successfully produced using resin transfer molding (RTM) techniques. Generally, the production of structural, optically transparent composites is challenging since it requires the combination of a very smooth mold surface with a sufficient control of resin flow that leads to no visible voids. Furthermore, it requires a minimum deviation of the refractive indices (RIs) of the matrix polymer and the reinforcement fibers. Here, a new mold design is described and three plates of optically transparent glass fiber-reinforced polymers (tGFRP) with reproducible properties as well as high fiber volume fractions were produced using the RTM process and in situ polymerization of an epoxy resin system enclosing E-glass fiber textiles. Their mechanical (flexural), microstructural (fiber volume fraction, surface roughness, etc.), thermal (DSC, TGA, etc.), and optical (dispersion curves of glass fibers and polymer as well as transmission over visible spectra curves of the tGFRP at varying tempering states) properties were evaluated. The research showed improved surface quality and good transmission data for samples manufactured by a new Optical-RTM setup compared to a standard RTM mold. The maximum transmission was reported to be ≈74%. In addition, no detectable voids were found in these samples. Furthermore, a flexural modulus of 23.49 ± 0.64 GPa was achieved for the Optical-RTM samples having a fiber volume fraction of ≈42%. [ABSTRACT FROM AUTHOR]

The demand for energy storage is growing, and the disadvantages of lithium‐ion batteries are being explored to overcome them. Accordingly, aqueous zinc‐ion batteries (ZIBs) are developing very rapidly, owing to their high safety, environmental friendliness, high abundance of resources, and high cost performance. Over the last decade, ZIBs have made remarkable progress through extensive efforts in the field of electrode materials and through fundamental understanding of non‐electrode components, such as solid‐electrolyte interphase, electrolytes, separators, binders, and current collectors. In particular, the breakthrough in using separators on non‐electrode elements should not be overlooked as such separators have proven key to conferring ZIBs with high energy and power density. In this Review, recent progress in the development of separators in ZIBs is comprehensively summarized based on their functions and roles in ZIBs, including the modification of conventional separators and the development of novel separators. Finally, the prospects and future challenges of separators are also discussed to facilitate ZIBs development. [ABSTRACT FROM AUTHOR]

Rapid advancements in the automotive and electronics industries have required the adoption of high-performance engineering polymers with better strength and less weight. The current research compared and evaluated the mechanical behavior, volumetric shrinkage, and rheological properties of two high performance engineering polymers, 40% glass fiber reinforced and 30% glass fiber reinforced. Tensile rods and rectangular bar-type specimens were injected, under three process conditions, respectively. The values of tensile strength, strain (%), impact strength, volumetric shrinkage, melt flow index and density were obtained from the injection tests. The results exposed that the mechanical properties of 40 % glass fiber reinforced PPS polymer is superior than those of 30% glass fiber reinforced PEI polymer as a result of amount of glass fiber. Furthermore, due to the semicrystalline form of the PPS polymer, the highest dimensional stability related with shrinkage has been obtained. Finally, this study has proven that glass fiber added high performance advanced polymers display great potential in engineering applications, and may provide a good potential for the development and application of electronics and automotive. Tensile stress values for PPS increased rapidly up to 1.50 % strain and then remained constant until 2.211%. [ABSTRACT FROM AUTHOR]

Polymer matrix composite (PMC) is advantageous in the unmanned aerial vehicle (UAV) field because of the phenomenal lightweight structural material injunction with the high specific strength/stiffness. In this study, a special type of PMC used in UAV as a structural material has been investigated. The microstructure revealed a uniform distribution of the reinforcement (E-glass fiber) in the matrix (epoxy) fabricated by the lay-up process. The study focuses on adjusting the matrix by investigating the effect of the solvent (methyl hydroxide) on the polymer matrix. Four compositions have been investigated by varying the methyl hydroxide content. Evidence of cross-link increase has been detected by Fourier transform infrared spectroscopy. The results show that the net resin achieved higher stability by adding methyl hydroxide in specific amounts that has shown an optimum enhancement on the matrix, reflected by the mechanical testing resulting in tensile strength and flexural strength. Aluminum oxide has been added to the optimum composition as a secondary reinforcement to increase the rigidity explained by the microstructure where a noticeable decrease in tensile/flexural strength is evident in the composite. [ABSTRACT FROM AUTHOR]

Moisture absorption in composites significantly influence the fiber/matrix interface regions and mechanical properties. Hence, it is very important to quantify the moisture storage in interfaces and correlate it to the mechanical behavior. The novelty of this article is that, for the first time, it explores the correlation of moisture absorption parameters with the mechanical behavior of composites. The paper studies four different types of moisture‐soaked composites—glass fiber/epoxy, carbon fiber/epoxy, ZnO nanowire incorporated glass fiber/epoxy, and ZnO nanowire incorporated carbon fiber/epoxy. One‐dimensional hindered diffusion model (1D HDM) was used for the extraction of moisture absorption parameters. The hindrance coefficient (ratio of bound to unbound moisture) of composites was found to increase proportionately with the increase in the volume of interfacial regions. Only in carbon fiber/epoxy composite, it did not increase proportionately due to the relatively larger degradation of interface. This was correlated well with mechanical test responses wherein carbon fiber/epoxy exhibited anomalous failure modes due to relatively larger degradation of interface. Numerical simulations were also carried out to describe the moisture absorption in composites. Numerical simulations of moisture absorption in composites using time‐varying boundary conditions matched very well with experimental as well as 1D HDM results. [ABSTRACT FROM AUTHOR]

The sudden occurrence of an earthquake induces a liquefaction effect on foundation soil, which causes a substantial increase in the uplift pressure acting on piles and causes structural damage to superstructures. This forms the basis of the necessity of experimenting with the behaviour of piles subjected to uplift loads and predicting their load-carrying capacity or resistance. Fibre-reinforced polymer (FRP) wraps are widely used for strengthening and retrofitting piles subjected to damage. The current study is aimed at determining the uplift load-carrying capacity or resistance of piles wrapped with basalt fibre-reinforced polymer (BFRP) and glass fibre-reinforced polymer (GFRP) sheets by experiment. Preliminary tests were conducted to identify the influence of BFRP and GFRP wraps on the mechanical strength properties of concrete. The mechanical strength of the specimen with the double wrapping of basalt and glass fibres in the perpendicular direction outperformed all other specimens. Moreover, the piles were wrapped with laminates and experimented on for their uplift capacity in dry and submerged conditions. The results indicate a considerable improvement in the uplift resistance of the piles compared with the unconfined piles. The BFRP and GFRP wraps improved the uplift resistance of the piles by 35.56% and 15.56%, respectively, higher than the unconfined pile for dry conditions. The angle of the interfacial friction in dry and submerged states was observed to be the maximum for the perpendicular direction for both of the FRP wraps, and the failure modes were compared. The simulated model showed a significant correctness for determining the uplift resistance of FRP-wrapped piles in dry and submerged states. The degree of agreement in the dry condition for the experimental results and finite element method was more than 94% for all fibre wraps. [ABSTRACT FROM AUTHOR]

This research was completed in the development of studies devoted to relations between the elastic modulus (MoE) and thermal expansivity (CTe) of different materials. This study, based on experimental data, confirmed the models of the relations between MoE and CTe under normal and heating temperatures for thermosetting epoxy polymers and glass-fiber FRPs in two variants (unfilled and filled by mineral additives), after the usual glassing and prolonged thermal conditioning (thermo-relaxation). The experiment was based on dilatometric and elastic deformation testing. Two models of MoE/CTe were tested: Barker's model and our authors relaxation model (MoE = f(CTe)), which is based on previous modelling of the non-linearity of the physical properties of polymers' supramolecular structures. The result show that the models' constants depend on composition; Barker's model is applicable only to polymers with satisfying agreement degrees in the range 10–20%; our model is applicable to polymers and FRPs with satisfying agreement degrees in the range of 6–18%. [ABSTRACT FROM AUTHOR]

High wear rates and frictional coefficients have always been the primary reasons for limiting the service life of critical elements such as pumps, couplings, bushings, bearings and gears. The premature and erratic failures are costing the industries extensive amounts of money every year. Additionally, under severe service conditions, the wear resistance requirements are higher, which greatly hinders the application of neat thermoplastics in different sectors. Hence, it is vital to enhance the tribological characteristics of thermoplastics. The mechanical and tribological properties of Polyamide 6, Thermoplastic Polyurethane, and glass fibre reinforced (GFR) Polyadmide 6 Composites of variable fibre volume fractions were investigated. Pin specimens of Polyamide 6 reinforced with (25%, 33%, and 50%) by volume of fibres were fabricated by an injection moulding process. The specimens were tested for tensile, compression, hardness, and wear under dry abrasive conditions using a pin-on-disc setup. Furthermore, the samples were scanned using micro-computed tomography (micro-CT), and the worn-out samples were analysed using field emission scanning electron microscopy. The experimental results showed that the fibre volume fraction was inversely proportional to the wear resistance of the prepared composite materials. This research will enable the industry partners to supply cutting-edge technologies to the global oil and gas industry that not only minimizes the well running cost but also improves the well resilience. [ABSTRACT FROM AUTHOR]

Glass fiber/polymer composites find extensive application in marine industry; however, the durability of theses marine structures has always been a matter of concern owing to their continuous exposure to harsh marine environment. The objective of this study is to consolidate and analyze the work that has been carried out so far, primarily focusing on the influence of the marine‐environment characteristics on water absorption and its subsequent impact on the mechanical properties of glass fiber reinforced composites. It is found that immersion time and operational temperature are the two prominent factors that influence the durability of these polymer composites. Moisture causes reversible changes such as plasticization and irreversible changes such as hydrolysis, cracking, and crazing which subsequently exerts a detrimental effect on the physical, chemical, and mechanical properties of epoxy resins. During the initial stage of water absorption, the moisture content increased rapidly with the immersion time, and then it increased slowly as the immersion time stretched until the moisture content in the specimen reached a saturation level. Prolong exposure in water not only led to a substantial deterioration in static mechanical properties; it also altered the mode of failure from a brittle matrix‐ductile fiber to ductile matrix‐brittle fiber. [ABSTRACT FROM AUTHOR]

In this paper, nanoparticles obtained by Sol-gel method have been incorporated as a filler in glass fiber/polyester composite in order to improve the mechanical properties of the resulting material. This work covered on the characterization and the study of the polymer matrix with 5 wt.%nano TiO 2 , 5 wt.%nano Al 2 O 3 , 5 wt.%nano SiO 2.The results obtained revealed that sol-gel powders with a spherical morphology have excellent thermal stability. Acoustic emission analysis was used to investigate the microscopic damage mechanisms and progression in glass fiber reinforced nanocomposites. Thus, acoustic emission from four modes of approval has been identified: matrix cracking, matrix/fiber decohesion, delamination and fiber breakage. This study shows the increase of mechanical performance and the decrease of damage modes of @Polyester. From the SEM images, the good dispersion of nanofillers, absence of agglomerates, the good affinity with the improving of the interface compatibility were presented. [ABSTRACT FROM AUTHOR]

Three-dimensional printed polymers offer unprecedented advantages for prosthetic applications, namely in terms of affordability and customisation. This work thus investigates the possibility of designing an additively manufactured prosthetic foot using continuous fibre-reinforced polymers as an alternative to composite laminate ones. A numerical approach was thus proposed and validated as a possible design tool for additively manufactured composite feet. This approach was based on explicit separate simulations of the infill, aiming to capture its homogenised engineering constants. The approach was validated on simple sandwich specimens with a different infill geometry: stiffness predictions were within the experimental standard deviation for 3D simulations. Such an approach was thus applied to redesign a laminated component of a foot prosthesis inspired by a commercial one with new additive technology. The new component was about 83% thicker than the reference one, with 1.6 mm of glass fibre skins out of about 22 mm of the total thickness. Its stiffness was within 5% of the reference laminated one. Overall, this work showed how additive manufacturing could be used as a low-cost alternative to manufacturing affordable prosthetic feet. [ABSTRACT FROM AUTHOR]