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This paper presents a long-term experimental investigation of E-glass/epoxy composites’ durability exposed to seawater at different temperatures. The thermoset composite samples were exposed to 23 °C, 45 °C and 65 °C seawater for a prolonged exposure time of 11 years. The mechanical performance as a function of exposure time was evaluated and a strength-based technique was used to assess the durability of the composites. The experimental results revealed that the tensile strength of E-glass/epoxy composite was reduced by 8.2%, 29.7%, and 54.4% after immersion in seawater for 11 years at 23 °C, 45 °C, and 65 °C, respectively. The prolonged immersion in seawater resulted in the plasticization and swelling in the composite. This accelerated the rate of debonding between the fibers and matrix. The failure analysis was conducted to investigate the failure mode of the samples. SEM micrographs illustrated a correlation between the fiber/matrix debonding, potholing, fiber pull-out, river line marks and matrix cracking with deterioration in the tensile characteristics of the thermoset composite.

This work aims to compare the hardness (H) and roughness (Ra) of glass/epoxy composites after being exposed to various hostile environments, which is possible because the constituents are always the same. Considering the stacking sequence [452, 902, −452, 02]s, the hardness increases for all solutions up to a certain exposure time, from which it decreases for longer immersion times. For the same stacking sequence, roughness had its highest increase (around 44.5%) for the alkaline solution after 36 days of immersion, while the highest decrease (around 25%) occurred for all mortars after 30 days of exposure. For the stacking sequence [02, 902]2s, the hardness varied in the opposite direction for acidic and alkaline solutions, observing a direct increase in H with immersion time. However, for samples immersed in oil, hardness decreased as a function of immersion time. In terms of roughness, there was a linear increase with immersion time for all samples, which increased linearly. Therefore, it can be concluded that the stacking sequence has a significant influence on hardness and roughness. Furthermore, knowledge of the variation in hardness and roughness is very important because it can be associated with the structural response of a composite exposed to hostile environments.

This study investigates the influence of silane-treated aluminum hydroxide on the mechanical performance of flame-retardant composites. These composites have potential applications for luggage bags, as a replacement for conventional plastics, offering more durability and lighter weight. Glass fabric was used as the reinforcement, while epoxy was used as the matrix material. To impart flame retardancy, aluminum hydroxide nanoparticles were used as fillers in different weight % age (5%, 10% and 15%). As these are inorganic particles and have compatibility issues with the matrix material, silane-coupling agents (Dynasylan® 6490 and Dynasylan Glymo) were used to treat these filler particles. Both the silane-coupling agents fraction used for treatment and the fillers fraction added to the composites were varied to determine the most optimum combination. The mechanical properties of the developed composites such as tensile, flexural, and short beam shear strength were investigated. The best results were exhibited by 10% aluminum hydroxide fillers treated with 1% (by weight) coupling agent (Dynasylan Glymo).

The study analysed epoxy–glass laminates containing carbonisate produced during medium-density fibreboard (MDF) waste pyrolysis were evaluated with respect to their hardness and their ability to withstand impact loads. All composite samples were prepared manually using a hand-laying method, using two resin–reinforcement ratios (60/40 and 65/35) and carbonisate additives in amounts of 5% and 7.5% by weight (with particle sizes < 500 µm). The mechanical properties were assessed on the basis of hardness tests using the Barcol method and impact tests using the Charpy method. To analyse the results, a normality assessment (Shapiro–Wilk) was performed, followed by a non-parametric analysis of variance based on ranks (Kruskal–Wallis). It was found that an increase in carbonisate content increases the surface hardness of composites while reducing their impact resistance, which confirms the existence of a typical trade-off between stiffness and energy absorption capacity. The most favourable mechanical properties were obtained for a composite containing 7.5% carbonisate material and a resin–reinforcement ratio of 60/40, which was characterised by the highest hardness (35.19 HBa), a moderate impact strength (43.56 kJ/m2) and the lowest variability of results. The statistical analysis confirmed significant differences between the tested samples and a quantitative relationship between hardness and impact strength. The results of the study indicate that carbonisate (MDF) using waste material as a filler provides a sustainable means of improving the stiffness and consistency of epoxy–glass composites, with only a negligible effect on their ability to resist fracture.

Laminated composites are generally made up of fibers reinforced using a polymer matrix. However, the delamination of such composites necessitates the incorporation of small quantities of nanoparticles to enhance the strong adhesion between the reinforcement and the matrix. This study evaluated the integration of graphene nanofillers as reinforcements in the epoxy matrix. The mechanical and thermal characteristics of the graphene composites were assessed according to the ASTM standards to determine the effect of graphene nanoparticles mixed with an epoxy matrix. First, graphene composite samples were fabricated with varying mixing weight percentages of graphene nanoparticles (1, 2, 3 and 4%) using the hand lay-up method. The tensile, flexural, and impact behaviors of the composites were then evaluated. Thermal characterization was performed using Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG) analysis. Scanning Electron Microscopy (SEM) was used to understand the fractography of the graphene composites. The test results confirmed that the inclusion of 3 wt% graphene nanoparticles enhanced the mechanical characteristics of the composite. In addition, the crystallization behavior and thermal stability were enhanced at a graphene content of 3%. Therefore, the inclusion of 3 wt% graphene nanoparticles in the e-glass/epoxy composite resulted in the enhancement of both the mechanical and thermal characteristics of the composite.

This paper presents the results of investigations of the mechanical properties of epoxy–glass composites with the addition of rubber recyclate. For the purposes of the study, seven variants of materials were designed and manufactured, which differed in terms of the percentage of recyclate content (3, 5 and 7%) and the way the recyclate was distributed in the composite (one, two and three layers with a constant share of 5%). Tests of comparative mechanical properties were carried out using a static tensile test. As a result of the conducted tests, the following values were obtained for all variants of materials: tensile strength (Rm), Young’s modulus (E) and percentage relative strain ε. In addition, for a deeper analysis of the results obtained, statistical calculations of Kolgomorov–Sinai EK-S metric entropy were performed on the experimental data sets, which were then analyzed. The results of the analysis indicate that the application of metric entropy calculations EK-S can be helpful in identifying changes in the internal structure of the composite material that occur during its loading, and which do not manifest themselves in any other tangible way. The data obtained as a result of the research can be used to optimize production processes and to determine the further direction of development of epoxy–glass composites with the addition of rubber recyclate, while saving time and resources.

In this study, the effect of nanoclay reinforcement on the mechanical and surface performance of glass/epoxy laminated composites was comprehensively investigated with the aim of jointly evaluating compression behavior and surface properties, which have been addressed only to a limited extent in the literature. In particular, the study aimed to reveal the role of the nanoclay ratio in the compression strength–hardness–wettability balance and to determine the optimum reinforcement level. To this end, glass/epoxy laminates containing nanoclay at weight ratios of 0, 1, 3, and 5 wt% were produced, and the specimens were characterized using compression tests, microhardness measurements, contact angle analyses, atomic force microscopy (AFM), and scanning electron microscopy (SEM). The results obtained showed that the addition of nanoclay significantly affected both the structural integrity and surface behavior of the composites. According to experimental findings, a 3 wt% nanoclay content provided the most balanced performance, resulting in an approximate 19.4% increase in compressive strength and a 7.3% increase in hardness, while also improving surface wettability. AFM analyses confirmed a more homogeneous nanoparticle distribution and increased surface roughness at this ratio, while SEM images revealed strengthened fiber–matrix interfacial bonding and limited crack propagation. In contrast, particle agglomerations and microvoid formation were observed at a 5 wt% nanoclay content, leading to a partial decrease in mechanical performance. In conclusion, this study demonstrates that nanoclay reinforcement is a critical parameter that controls not only the mechanical strength but also the surface functionality of glass/epoxy composites, and provides a comprehensive assessment for determining the optimal nanoclay ratio for structural applications. Highlights Glass/epoxy laminates were reinforced with 1–5 wt% nanoclay and systematically characterized. Optimal nanoclay loading (3 wt%) enhanced compressive strength by ≈ 19.4% and hardness by ≈ 7.3%. AFM and contact angle analyses revealed improved surface wettability and nanoparticle dispersion. SEM micrographs confirmed crack deflection and stronger fiber–matrix adhesion at moderate filler levels. Excessive nanoclay (5 wt%) led to agglomeration and microvoids, reducing mechanical performance.

When creating polymer-based composites, plain weave fabrics and micron-sized fillers offer bidirectional strength and reduced voids/inhomogeneity. In the present work, It was investigated how glass fabric reinforced epoxy composite (G-E) performed during three-body abrasive wear with and without ceramic fillers (SiO2, Al2O3, graphite, and fly ash cenospheres). In experiments, loads of 20 N and 40 N were applied at various abrading distances of 500 m, 1000 m, 1500 m, and 2000 m. According to the results of sand abrasive wear test, the specific wear rates of G-E based composites are sensitive to fibre and filler/matrix adhesion. Under all tribo-test settings, the SWR for all particulate G-E composites decreases in the following order: G-E > Gr/G-E > SiO2/G-E > Al2O3/G-E > fly ash cenosphere/G-E. Furthermore, the specific wear rate of the fly ash cenosphere filled G-E composites were found to be lower than the G-E and other filler materials filled G-E composites. There was 38.7% reduction in the specific wear rate at 40 N, 2000 m in fly ash cenosphere filled G-E composite. As per the evidence of scanning electron microscope images of worn-out surfaces, mechanisms such as ploughing, fibre breakage, fibre pull-out, fibre thinning, and a network of microcracks caused the wear in composites.

Due to commonly observed adhesive fracture, the interphase regions between fibers and matrix have often been considered a critical design factor in polymer matrix composites. This study uses molecular dynamics simulation to explore the effects of two modifications at a glass fiber and epoxy interphase by adding a silane sizing and a cellulose nanocrystal particle. The interphase thickness increases by 1 nm and by 3.8 nm, respectively, when silane coating, a combination of silane and a 36-chain cellulose nanocrystal are added. Furthermore, the shear modulus and strength of the interphase increase by around 120% and 415% in the case of silane and by about 70% and 240% in the case of a cellulose nanocrystal. When both cellulose nanocrystal and silane are added at interphase, the shear modulus and strength increase by approximately 125% and 265%, respectively. The cellulose nanocrystal particle is physically absorbed on the glass fiber surface without silane, and it is physically confined in a region created by covalent bonds between silane and epoxy when silane is present. In both cases, a cellulose nanocrystal particle increases the nanoscale roughness at a glass fiber surface, leading to improved shear properties at the interphase.

Leaf springs play a vital role in heavy-duty vehicles by offering substantial load support, durability, and convenient maintenance. Lightweight leaf springs enhance vehicle performance, offering benefits like improved fuel efficiency and a smoother ride. Glass fiber reinforced composites enhance fuel efficiency and durability, providing corrosion resistance. Their design flexibility improves ride comfort, and damping properties enhance vehicle stability. The examination conducted through finite element analysis, utilizing ANSYS software, demonstrated a substantial 75.32% decrease in weight for the E-Glass-Epoxy composite leaf spring (GECLS), affirming its efficacy in enhancing strength, reducing weight, and enhancing stiffness. This underscores its superiority as a viable alternative to traditional steel leaf springs (SLS) in vehicular applications. The mono-GECLS exhibited a natural frequency that was found to be 1.9 times higher than that observed in the traditional SLS. It indicates the potential to mitigate resonance issues. After analysing the SLS and GECLS using ANSYS, it was observed that the GECLS exhibits greater values in deflection, natural frequency, and strain energy, measuring 4.659 mm, 29.98 Hz, and 440.68 mJ, respectively, compared to its steel counterpart. Conversely, the SLS demonstrates elevated values in stress, mass, and density, with readings of 283.84 MPa, 3.7695 kg, and 5920 kg/m³, respectively.