Papers by Keyword: Epoxy Resin

Abstract: Reactive structural material (RSM) has been used in modern warheads, binders in which has limitations in achieving high energy release and excellent mechanical properties. Epoxy resins, with their high oxygen content and good mechanical strength, show great potential as alternatives to traditional binders. In this work, two cured epoxy systems with different oxygen contents were prepared and tested under simulated explosion conditions. During detonation, combustion of resin fragments was observed, resulting in a peak blast pressure about 1.7 times higher than that of the bare explosive. Additional dispersion and combustion tests on resin powders confirmed that a higher oxygen content and more C-O bonds led to faster combustion and stronger pressure output. These results suggest that increasing the oxygen-rich structure of epoxy resins can effectively enhance both the combustion behavior and energy release, offering a new approach for developing high-performance binders in reactive materials.

Abstract: Glass fiber-reinforced composites (GFRC) are widely used in structural applications due to their high strength-to-weight ratio and excellent fatigue resistance. Nevertheless, the mechanical integrity of adhesive joints remains a critical challenge in composite structural engineering. This study aims to investigate the influence of varying epoxy resin mixing ratios on the lap shear strength of glass fiber-reinforced composite joints. Two experimental schemes were conducted by varying the resin-to-hardener composition in the range of 10:50 to 70:50 (by weight). Single-lap joint specimens were fabricated and tested in accordance with ASTM D5868-95. The results demonstrated that a resin-to-hardener ratio of 50:50 yielded the maximum lap shear strength, reaching 5.71 MPa for resin system A and 5.28 MPa for resin system B. This ratio indicated a stoichiometric balance between epoxy groups and active amine groups, resulting in optimal curing with maximum cross-linking density. Deviations from this optimal ratio, either due to excess or deficiency of one component, led to a significant reduction in joint strength, as indicated by brittle fracture or weak adhesive bonding. These findings highlight the importance of precise control over epoxy adhesive formulations to ensure reliable mechanical performance in composite structures. The implications of this research contribute to the development of more durable and efficient adhesive systems, particularly for GFRC applications in the automotive, aerospace, and marine industries.

Abstract: This study focuses on the development of sustainable composite materials for automotivebody panels by utilizing sugarcane bagasse and bamboo fibers reinforced with epoxy resin. Theagricultural by-products were first sun-dried, mechanically processed into fine powder, andchemically treated to improve interfacial bonding before being incorporated into the epoxy matrix.Composite specimens were fabricated through a controlled lay-up process and tested for flexuralstrength and impact resistance in accordance with ASTM standards. Experimental results revealedthat sugarcane bagasse composites exhibited the highest flexural strength of 47 MPa, while bamboocomposites contributed greater ductility and flexibility under load. Notably, a hybrid formulation ofbagasse and bamboo fibers achieved the best balance of properties, recording an impact resistance of187 J/m, which is comparable to commonly used polymers. These findings highlight that naturalfiber-based composites not only offer mechanical performance suitable for exterior automotiveapplications but also provide significant advantages in terms of weight reduction, cost-effectiveness,and environmental sustainability.

Abstract: The degradation behavior of adhesion between cycloaliphatic epoxy resin and copper under high temperature and high humidity conditions was investigated. The Cu/resin joints were aged at 175°C and at 85°C in 85% R. H. The degradation behavior of the joint interface was analyzed by tensile tests and Fourier infrared transform spectroscopy (FT-IR). As a result, it was confirmed that the adhesion strength was retained after aging at 175°C for 1000 h, while it decreased with an increase in the aging time by aging at 85°C in 85% R. H. Furthermore, the interfacial fracture mode increased with aging at 175°C. In contrast, cohesive fracture was the main fracture mode and hardly changed by aging at 85°C in 85% R. H. The FT-IR analysis results showed that the peak intensity of the carbonyl group increases and that of the methylene group decreases by aging at 175°C. The result indicates that the resin was oxidized. Moreover, the peak intensities of carboxy and hydroxyl groups increased and that of ester groups decreased by aging at 85°C in 85% R. H. The results suggest that ester groups may be hydrolyzed due to aging and thus the adhesion is degraded.

Abstract: This study investigates the degradation of adhesion between aluminum alloy and epoxy resin under high-temperature and high-humidity conditions. As next-generation power modules increasingly demand enhanced reliability, understanding the factors that affect metal/resin adhesion has become crucial. In this work, fourier transform infrared spectroscopy and adhesion strength testing were employed to evaluate the chemical and mechanical changes occurring at the interface during accelerated aging. FT-IR analysis revealed that the peak intensity of the carbonyl C=O peak in the epoxy resin decreased with aging time, while the aromatic C=C peak remained largely unchanged. The degree of moisture absorption, calculated from the ratio of these peak intensities, increased with the progress of aging. In addition, moisture uptake was found to weaken hydrogen bonding at the A1050/epoxy resin interface, and this effect was more pronounced in specimens with thinner resin layers. Adhesion strength tests showed a significant reduction in adhesive strength with prolonged exposure to high humidity and temperature. Fracture surface observations further indicated a shift in failure mode from cohesive to interfacial with aging. These results suggest that moisture-induced chemical changes at the interface contribute to the degradation of adhesion.

Abstract: The aim of this research seeks to investigate the mechanical properties of Borassus flabellifer (Borassus palm) and Carica papaya (papaya) hybrid composites fibers reinforced in regards to strength, stiffness, and toughness under different test conditions. It also compares the performance of hybrid composites with composites based on individual fibers. The study involves two groups of composite materials. Group 1. The analysis of ultimate tensile strength of Borassus palm and Carica papaya composite value is 17.020 N/mm². Group 2. The analysis of impact strength of Borassus palm and Carica papaya composite value is 0.35. The hybrid composites, made from Borassus palm and papaya fibers are have very good Tensile and impact strength. That can be an alternative to synthetic fibers. In this study it observed that the hybrid composites, made from Borassus palm and papaya fibers are very suitable for mechanical applications.

Abstract: Natural fibre composites are gaining importance in engineering and automotive sectors due to their sustainability, lightweight nature, and cost-effectiveness. However, their flexural modulus and other mechanical properties require enhancement to meet industrial standards. This study aims to improve the performance of hybrid composites reinforced with hemp, jute, and coir fibres in an epoxy matrix. Specimens were fabricated using the hand lay-up technique followed by compression moulding and tested according to ASTM standards. Mechanical characterization included hardness, tensile, flexural, compressive, and impact tests, along with water absorption analysis. The results demonstrated significant improvements, with maximum hardness of 80 HRM, tensile strength of 16.95 N/mm², compressive strength of 5.268 N/mm², flexural strength of 95.96 N/mm², and impact resistance of 0.20 J. Water absorption varied between 11.6% and 25%, depending on resin-to-fibre ratios. One-way ANOVA confirmed statistically significant differences among formulations (p = 0.005), validating the effect of fibre–resin composition. The optimal formulation (75% epoxy with balanced fibre reinforcement) achieved superior mechanical performance, establishing hybrid natural fibre composites as a promising eco-friendly alternative to conventional materials.

Abstract: The mode I interlaminar fracture toughness, G_IC, of unidirectional fiber-reinforced polymer matrix composite laminates was determined using the double cantilever beam (DCB) specimens. To ensure real-time correspondence with the growing crack length, load and displacement, the Digital Image Correlation (DIC) technology, a non-contact optical measurement technique, was selected for the fracture toughness tests in this paper. In addition, fracture toughness calculation programs were used to accelerate data processing.The results indicated that the DIC technology was reliable compared with the traditional technology (magnifying glass). The G_IC values obtained from all the three calculation methods (CC, MBT and MCC method) differed by no more than 3%. The SEM analysis showed that the crack propagation occurred along the fiber-matrix interface, resulting in plastic cracking and microcracks in the matrix. The observed intact fiber bundles indicated the matrix-dominated cracking in crack propagation, with localized fiber fracture at high stress and a small amount of fiber bridging during separation.

Abstract: The marine atmospheric environment exposure test of BL-60 basalt composites was carried out in Hainan test station. The effects of marine atmospheric environment on the aging behavior of composites were studied by macro and micro morphology, moisture absorption rate, bending strength, linear expansion coefficient, glass transition temperature and infrared spectrum. The results show that the moisture absorption of the composite matrix plays a dominant role in the initial stage of exposure to the marine atmospheric environment ( 0.25 years ). With the extension of the test time ( ≥0.5 years ), the surface epoxy resin is aged and the basalt fiber is exposed. The intensity of the resin characteristic peak is obviously weakened, and the resin pulverization and shedding are greater than the moisture absorption effect. After one year of exposure to the marine atmospheric environment, the basalt fiber is almost completely exposed to the surface and exhibits a uniform cross-woven structure, and the resin characteristic peaks all disappear. After exposure to marine atmospheric environment for 1.5 years, the glass transition temperature of the composites decreased from 116.9 °C to 82.79 °C, the linear expansion coefficient decreased from 49.65 μm/(m·°C) to 31.43 μm/(m·°C), and the bending strength decreased from 570 MPa to 513 MPa. The experimental results show that the marine atmospheric environment causes aging damage to the hygroscopicity, macro and micro morphology and chemical structure of BL-60 basalt composites, which leads to the decrease of thermal and bending properties.

Abstract: Epoxy resins are widely recognised as the most commonly used polymers, playing a crucial role in both industrial and domestic applications; however, the effect of secondary amine volume on the electrophoretic deposition (EPD) performance of epoxy resin remains underexplored. This study investigates the influence of varying volumes of N-methylethanolamine (MEA) during the synthesis of cationic epoxy on the chemical composition, thickness, surface morphology, and dielectric properties of electrodeposited epoxy coatings at a voltage of 60 V. Cationic diglycidyl ether of bisphenol A (DGEBA) epoxy resin was formulated with 0.5, 1.0, and 1.5 ml MEA, and then deposited onto galvanised substrates via EPD. Increasing the MEA volume from 0.5 ml to 1.5 ml during the formulation of cationic DGEBA resulted in a 50.6% reduction in deposited coating thickness (from 46.6 µm to 23.0 µm) and a 98% decrease in the corresponding dielectric constant (from 102 to 1.98 at a frequency of 1.27 Hz). These variations were confirmed by Fourier-transform infrared spectroscopy, electrochemical impedance spectroscopy, and field-emission scanning electron microscopy, which indicated changes in chemical bonding and surface uniformity. The findings highlight the critical role of MEA volume in determining the performance of electrodeposited epoxy coatings and offer guidance for optimising EPD formulations for improved insulation and structural stability.