Reinforced Epoxy Resin Research Articles

In-plane compressive properties of 3D braided jute/epoxy composite honeycombs: Structure-property relationships

To achieve the integrity of the honeycomb structure without interlocking or bonding, a 3D braided honeycomb structure was designed and developed using natural fiber (jute) reinforced epoxy resin. To optimize the in-plane compressive performance of 3D braided composite honeycombs, the effects of resin, unit cell opening angle, and joint wall length on the in-plane compressive strength, deformability, stiffness and energy absorption were investigated. Furthermore, a theoretical model was established between braiding parameters, geometric parameters of honeycomb cell structure, and in-plane compressive modulus. It is found that if 3D braided composite honeycombs are designed for high load-bearing capacity, it is necessary to reduce the resin strain to failure, increase free wall columns, align the angle between the free wall with the main loading direction, or load along the braiding direction. If the design objective is to maximize the energy absorption, the number of cell rows must be maximized. This study establishes the relationship between braiding parameters, honeycomb geometric parameters, and the in-plane compression performance of the 3D braided composite honeycomb, providing a reference for its structural design and performance optimization.

Effects of the Rate Dependency of a Matrix Material on the Tensile Response of Plain Weave Carbon Fabric Reinforced Epoxy Composites

Effects of the Rate Dependency of a Matrix Material on the Tensile Response of Plain Weave Carbon Fabric Reinforced Epoxy Composites

Rational design of glass fiber reinforced epoxy resin with thermal conductivity but electrical insulation through a multi-level network

Rational design of glass fiber reinforced epoxy resin with thermal conductivity but electrical insulation through a multi-level network

Friction Behaviors and Wear Mechanisms of Carbon Fiber Reinforced Composites for Bridge Cable.

Carbon fiber reinforced epoxy resin composites (CFRP) demonstrate superior wear resistance and fatigue durability, which are anticipated to markedly enhance the service life of structures under complex conditions. In the present paper, the friction behaviors and wear mechanisms of CFRP under different applied loads, sliding speeds, service temperatures, and water lubrication were studied and analyzed in detail. The results indicated that the tribological properties of CFRP were predominantly influenced by the applied loads, as the tangential displacement generated significant shear stress at the interface of the friction pair. Serviced temperature was the next most impactful factor, while the influence of water lubrication remained minimal. Moreover, when subjected to a load of 2000 g, the wear rate and scratch width of the samples exhibited increases of 158% and 113%, respectively, compared to those loaded with 500 g. This observed escalation in wear characteristics can be attributed to irreversible debonding damage at the fiber/resin interface, leading to severe delamination wear. At elevated temperatures of 100 °C and 120 °C, the wear rate of CFRP increased by 75% and 112% compared to that at room temperature. This augmentation in wear was attributed to the transition of the epoxy resin from a glassy to an elastic state, which facilitated enhanced fatigue wear. Furthermore, both sliding speed and water lubrication displayed a negligible influence on the friction coefficient of CFRP, particularly under water lubrication conditions at 60 °C, where the friction coefficient was only 15%. This was because the lubricant properties and thermal management provided by the water molecules, which mitigated the frictional interactions, led to only minor abrasive wear. In contrast, the wear rate of CFRP at a sliding speed of 120 mm/s was found to be 74% greater than that observed at 60 mm/s. This significant increase can be attributed to the disparity in sliding rates, which induced uncoordinated deformation in the surface and subsurface of the CFRP, resulting in adhesive wear.

Improving interlaminar fracture toughness and compression after impact strength of carbon fiber reinforced epoxy composites by interleaving electrospinning polyethersulfone nanofiber

AbstractThe effect of membrane thickness of electrospinning polyethersulfone (PES) nanofiber membranes on interlayer toughness and impact resistance of carbon fiber reinforced epoxy resin (CF/EP) composites are researched. Intercalation composites with different nanofiber membrane thicknesses, ranging from 10 to 50 μm, are tested at mode I and mode II interlaminar fracture toughness. The impact resistance of nanofiber membranes with different thicknesses is evaluated by the compression after impact (CAI) strength test. Moreover, nanofiber toughening contributions are investigated using the crack path and surface analysis. Results indicate that PES nanofibers increase the toughness of interlayer resin and change the interlaminar crack propagation path of CF/EP composites. The optimum nanofiber membrane thickness for mode I (GI = + 58%) and CAI (CAI strength = + 33%) is 50 μm, while for mode II is 30 μm (GII = + 16.4%). The storage modulus of CF/EP composites increases with the increase of nanofiber membrane thickness. The study also confirms the insertion of a nanofiber membrane slightly improves the tensile strength and interlaminar shear strength (ILSS) of the CF/EP composites.Highlights PES nanofiber membranes of different thicknesses were inserted into the CF/EP. CAI and GI improved by 33% and 58%, respectively of CF/EP composites. The relationship between interlayer fracture toughness and CAI was discussed.

Determination of Mass Attenuation Coefficient of Jute Reinforced Epoxy Resin Composite as Tissue Equivalent Phantom

Abstract The mass attenuation coefficient is a fundamental parameter in radiation physics and plays a pivotal role in understanding the interaction of ionizing radiation with matter. This study aims to determine mass attenuation coefficients of newly developed tissue equivalent phantom fabricated from jute fibres reinforced with epoxy resin and activated carbon as a filler. The composites were prepared based on four different filler levels (ranging from 0wt% to 5wt%). The produced phantoms are characterized in terms of half-value layer HVL (cm) relating to linear attenuation coefficient, μ (cm−1). The linear and mass attenuation coefficients for the composites with different wt% of filler were determined at three different kV settings of the X-ray generator, covering the lower energy range of normal diagnostic practice (50 kVp, 102 kVp and 109 kVp) and by using the half-value layer (HVL) method. Aluminum filters were used to determine the HVL values and subsequently calculated the attenuation coefficients. The value of attenuation coefficients of fabricated composite materials was contrasted with theoretical value through the utilization of XCOM software at the same energy levels. The results were in good agreement for all ranges of wt% composite. These findings not only have significant practical implications for radiation-related technologies and applications but also enhance material characterization techniques. Hence, the attenuation measurements conducted in this study validate the suitability of jute-reinforced epoxy resin, filled with activated carbon as a phantom material that mimics human tissue.

Structural Optimization of a High-Performance Green Sandwich Made of Sisal Reinforced Epoxy Facings and Balsa Core.

Within the range of composite laminates for structural applications, sandwich laminates are a special category intended for applications characterized by high flexural stresses. As it is well known from the technical literature, structural sandwich laminates have a simple configuration consisting of two skins of very strong material, to which the flexural strength is delegated, between which an inner layer (core) of light material with sufficient shear strength is interposed. As an example, a sandwich configuration widely used in civil, naval, and mechanical engineering is that obtained with fiberglass skins and a core of various materials, such as polyurethane foam or another lightweight material, depending on the application. Increasingly stringent regulations aimed at protecting the environment by reducing harmful emissions of carbon dioxide and carbon monoxide have directed recent research towards the development of new composites and new sandwiches characterized by low environmental impact. Among the various green composite solutions proposed in the literature, a very promising category is that of high-performance biocomposites, which use bio-based matrices reinforced by fiber reinforcements. This approach can also be used to develop green sandwiches for structural applications, consisting of biocomposite skins and cores made by low-environmental impact or renewable materials. In order to make a contribution to this field, a structural sandwich consisting of high-performance sisal-epoxy biocomposite skins and an innovative renewable core made of balsa wood laminates with appropriate lay-ups has been developed and then properly characterized in this work. Through a systematic theoretical-experimental analysis of three distinct core configurations, the unidirectional natural core, the cross-ply type, and the angle-ply type, it has been shown how the use of natural balsa gives rise to inefficient sandwiches, whereas performance optimization is fully achieved by considering the angle-ply core type [±45/90]. Finally, the subsequent comparison with literature data of similar sandwiches has shown how the optimal configuration proposed can be advantageously used to replace synthetic glass-resin sandwiches widely used in various industrial sectors (mechanical engineering, shipbuilding, etc.) and in civil engineering.

Chemical and Solvent-Based Recycling of DGEBA-Based Epoxy Thermoset and Carbon-Fiber Reinforced Epoxy Composite Utilizing Imine-Containing Secondary Amine Hardener.

Epoxy systems are essential in numerous industrial applications due to their exceptional mechanical properties, thermal stability, and chemical resistance. Yet, recycling epoxy networks and reinforcing materials in epoxy composites remains challenging, raising environmental concerns. The critical challenge is the recovery of well-defined molecules upon depolymerization. To address these issues, an innovative strategy is developed utilizing imine-containing secondary amine hardener (M1). The reaction of M1 with DGEBA produced high-performance epoxy thermoset P1, which exhibits Young's modulus of 2.18 GPa and tensile strength of 63.4 MPa, and excellent stability in neutral aqueous conditions. Upon carbon-fiber reinforcement, Young's modulus and tensile strength are significantly elevated to 10.99GPa and 328.3MPa, respectively. The reactive secondary amine functionalities enabled the tailored network to display a well-defined growth pattern, yielding only well-defined molecules and intact carbon fibers upon acidic depolymerization. Consequently, the recycled polymers retained properties identical to those of P1. Notably, it is discovered that despite the cross-linked nature of the epoxy networks, complete dissolution in dichloromethane facilitated straightforward solvent-based recycling, allowing the recovery of undamaged carbon fibers and an epoxy thermoset with properties matching the virgin material. Presented novel monomer design and approach showcased two important and efficient recycling options for epoxy systems.

Carbon black: a thermally conductive reinforcement for epoxy based composite

Carbon black: a thermally conductive reinforcement for epoxy based composite

A Novel Investigation on Microstructural Analysis of a Rupture GRE Composite Pipe for Underground Fire Water System

This study investigates how underground fire water systems using Glass Reinforced Epoxy (GRE) pipes are affected by aging. Over time, GRE pipes can degrade, potentially reducing their expected lifespan. The study compared damaged and undamaged areas of pipes to assess how damage impacts their structural integrity. Microscopic and chemical analyses (SEM and EDX) were performed on pipe samples from different locations of the pipe. Mechanical testing (following ASTM standards) was conducted beforehand. Analyses revealed that as damage increased (closer to damaged area), the levels of carbon (C) and oxygen (O) changed significantly with the weight percentage exposed 45.62% difference and 11.62% difference, respectively, as compared with the undamaged area. This suggests that the epoxy resin degrades with age, releasing these elements. Additionally, the presence of foreign objects around the pipes can affect how they bear loads. These findings highlight the importance of understanding how aging and surrounding conditions can influence the performance of GRE pipes in real-world fire water systems.

Effect of Fibre Reinforcement on Compressive Strength and Compressive Modulus of Epoxy Granite

Abstract The main focus of the paper is to study the effect of fibre reinforcement on compressive strength and compressive modulus of epoxy granite. To investigate the effect of fibre reinforcement, two compositions were considered likes 20% Epoxy and 80% Granite without fibre reinforcement and 20% Epoxy, 75% Granite and 5% fibre reinforcement. Based on the literature studied, three types of fibre were considered viz. steel fibre, carbon fibre and basalt fibre. Three specimens of each type of fibre i.e. nine specimens and three specimens without fibre reinforcement were prepared. The obtained maximum compressive strength and compressive modulus of epoxy granite without reinforcement is 91.70 MPa and 3.5 GPa for the composition of 20% epoxy and 80% granite. The observed maximum compressive strength of 78.57 MPa for 20% epoxy and 75% granite with 5% carbon fibre reinforcement epoxy granite (CFEG) which is much higher than steel fibre reinforced epoxy granite (SFEG) with 20% epoxy and 75% granite and basalt fibre reinforced epoxy granite (BFEG) with 20% epoxy and 75% granite. The computed compressive modulus is 2.7 GPa for SFEG with 5% fibre which greater than CFEG and BFEG with the same fibre content.

Experimental characterization of hemp woven fabric reinforced epoxy resin composites produced without heat treatment

Experimental characterization of hemp woven fabric reinforced epoxy resin composites produced without heat treatment

Design and fabrication of an accelerometer structure using glass fiber reinforced epoxy resin for seismic P-wave early warning

Earthquake early warning represents a vital and effective strategy for mitigating earthquake-related losses. Among the existing sensors for earthquake early warning, MEMS accelerometers involve complex manufacturing process, leading to high research and development costs and long cycles. Traditional mechanical sensors are bulky, costly, hence not suitable for large-scale, high-density monitoring network. In this study, a low-cost accelerometer using glass fiber reinforced epoxy resin is proposed for longitudinal seismic waves (P-waves) early warning. Both theorical and finite element analysis are carried out to define and optimize the initial structure of the accelerometer. A pre-deformation structure is implemented into the spring suspension system to offset the influence of the sensor’s gravity, so that a self-balanced state in the direction of gravity is achieved. The simulation results show that the accelerator can achieve an eigenfrequency of 12.67 Hz, a Q-value of 49.2, and mechanical thermal noise of 1.72×10-9g/Hz. Based on the simulation results, the accelerometer’s structure is processed using a computer numerical control (CNC) milling machine, and tested by collecting the voltage signals when the accelerometer’s structure undergoes an impact in the direction of the gravity. The measured eigenfrequency is around 10 Hz, and the signal attenuation rate closely aligns with the simulation results. The accelerometer structure has dimensions within 6 cm and a relatively simplified manufacturing process, making it a cost-effective solution for the development of large-scale, high-density earthquake early warning systems.

Effects of Dolomite Geopolymer Filler on Mechanical Properties of Glass Fibre Reinforced Epoxy Composite

Effects of Dolomite Geopolymer Filler on Mechanical Properties of Glass Fibre Reinforced Epoxy Composite

Improved interfacial properties of carbon fiber reinforced epoxy resin composite by in‐situ self‐assembled mental‐phenolic networks

AbstractThe chemical modification of carbon fiber surface often uses toxic reagents and harsh reaction conditions, while the preparation process of metal‐phenol networks (MPNs) is simple, rapid, non‐toxic and harmless, which provides a direction for alleviating environmental problems. In this study, tannic acid (TA) was coordinated with Fe3+ to form MPNs, which was coated on the surface of carbon fibers through π‐π interaction. The results indicated that oxygen functionalities on the surface of the MPN coating can facilitate better adhesion between the carbon fiber and the epoxy resin, when the molar ratio of TA to Fe3+ is 1:3 and the pH is 4, the interlaminar shear strength (ILSS) performance of the composite material reaches its optimal level. In addition, a green and non‐destructive method is provided for the surface modification of carbon fiber, which can effectively optimize the interfacial properties of carbon fiber reinforced polymer (CFRP) composites.

Catalytic alcoholysis of fiberglass reinforced epoxy resin composites

The article presents the results of a study of alcoholysis of fiberglass reinforced epoxy resin composites obtained by vacuum infusion. To intensify alcoholysis, chlorides, nitrates and sulfates of cobalt (II) and copper (II) were introduced into the reaction medium in an amount of 5% of the mass of ethyl alcohol for each system. The efficiency of the system was assessed based on data from the analysis of mass change of composite samples during alcoholysis, thermogravimetric analysis and scanning electron microscopy. It was found that the presence of metal chlorides contributes to 5 times increase of the alcoholysis velocity. The residual strength of the recovered fiber samples obtained is at least 95%.

Durable microstructure-based superhydrophobic composite with photothermal performance for multifunctional application

Nowadays, multifunctional superhydrophobic coating has drawn widespread attention by virtue of its great water-repellent property, whereas the fragile mechanical and chemical durability of superhydrophobic coating greatly limits its practical application. Herein, a robust and multifunctional superhydrophobic composite coating (CFRE-SP@Fe3O4) with anti-corrosion, delay-icing and self-deicing performance is constructed via simple imprinting-demolding process on the carbon fiber reinforced epoxy resin (CFRE) surface and post-deposition modification with polydimethylsiloxane (PDMS) and epoxy resin modified Fe3O4 nanoparticles. The obtained CFRE-SP@Fe3O4 coating displays a superhydrophobic property with a WCA of 155° ± 1.2°. By virtue of the protection effect of the robust micro-grid structures for the inner superhydrophobic Fe3O4 nanoparticles (SP@Fe3O4), the CFRE-SP@Fe3O4 coating still maintains great superhydrophobicity after linear friction for 100 times. Additionally, compared with the carbon steel treated with CFRE, the impedance modulus at lowest frequency of CFRE-SP@Fe3O4 coating treated group further increase with a value of 107 Ω·cm2, confirming the excellent anti-corrosion performance. Owing to the air pocket captured by the micro-/nanostructure on the superhydrophobic surface, the icing time of the CFRE-SP@Fe3O4 surfaces extends from 60 s to 2130 s. Moreover, combined with the photothermal conversion performance of carbon fiber and Fe3O4 nanoparticles, the ice on the CFRE and CFRE-SP@Fe3O4 coatings surfaces begin to melt 137 s, displaying the excellent self-deicing performance.

Pyrolysis process and products characteristics of glass fiber reinforced epoxy resin from waste wind turbine blades

The installed wind power capacity has reached up to 906 GW globally meaning the usage of wind turbine blades (WTBs) with around 9.06 Mt. The waste WTBs with a rapid growth was estimated to be 72.0 kt in 2022 based on the projected lifetime of 20 years. The recycling of fibers reinforced thermoset polymer from waste WTBs has become a knotty environmental issue. This work aimed at studying the pyrolysis behaviors of a glass fibers reinforced epoxy resin materials from a waste WTBs, and revealing the impacts of pyrolysis atmosphere and temperature on the pyrolysis products. It was found that the black glass fibers with deposited carbon and the clean glass fibers were obtained by pyrolysis in N2 and air, respectively. Both pyrolysis in N2 and air produced the pyrolysis oil and gas with similar compositions. The preferable strength of fibers and yield of oil could be obtained at applicable pyrolysis temperature of 450 °C. The oil yields were 13.17 wt.-% and 11.93 wt.-% by pyrolyzing at 450 °C in N2 and air, respectively. The analysis of pyrolysis pathway suggested that the oxygen promoted the decomposition of epoxy resin into small molecules of gases by pyrolysis in air. The utilization of recycled products gas was also discussed. The findings of this work could provide some suggestions to explore a route with low cost to recycling the waste WTBs by pyrolysis.

Experimental Design and Analysis of MWCNT, Nanoclay and Zinc Oxide Nanofillers on Bi-directional-Chopped Stranded Glass Fibre Reinforced Epoxy matrix on Mechanical Properties using Multi Response Performance Index Approach

Experimental Design and Analysis of MWCNT, Nanoclay and Zinc Oxide Nanofillers on Bi-directional-Chopped Stranded Glass Fibre Reinforced Epoxy matrix on Mechanical Properties using Multi Response Performance Index Approach

Interfacial property enhancement of carbon fiber/epoxy composites via constructing a gradual modulus interphase with a waterborne bio‐based spiro diacetal epoxy emulsion

AbstractIn this article, to explore the utilization of bio‐based epoxy resin in the preparation of sizing agents for carbon fibers (CFs), a bio‐based epoxy emulsion (S‐P‐S) derived from spiro diacetal epoxy (SDE) resin was prepared and compared to the traditional diglycidyl ether of bisphenol A (DGEBA) based emulsion (D‐P‐D) and a mixed emulsion of S‐P‐S and D‐P‐D (S‐P‐S&D‐P‐D). The CF sized with S‐P‐S (CF‐(S‐P‐S)) showed improved surface oxygen content (22.86%) and roughness (40.9 nm), enhancing wettability and interfacial bonding between the fiber and the matrix. Nanoindentation test and AFM results showed the enhanced interfacial stiffness and a gradual modulus interphase with a thickness of 381 nm in CF‐(S‐P‐S) reinforced epoxy resin composite (CF‐(S‐P‐S)/EP). Therefore, the resulting CF‐(S‐P‐S)/EP composite possesses the best mechanical properties, with the transverse fiber bundle tensile (TFBT) strength of 27.3 ± 1.45 MPa and the interfacial shear strength (IFSS) of 85.6 ± 8.26 MPa. These results highlight the potential of the SDE‐based emulsion (S‐P‐S) to enhance the interfacial properties and mechanical performance of CF/EP composite, offering a sustainable alternative to conventional petroleum‐based epoxy resins.Highlights Emulsion (S‐P‐S) was prepared using spiro diacetal epoxy (SDE) for carbon fiber sizing. Properties of S‐P‐S sized CF (CF‐(S‐P‐S)) and its composite were evaluated. Spiro diacetal structure created a gradual modulus interphase in CF‐(S‐P‐S)/EP. The interfacial properties of the CF‐(S‐P‐S)/EP composite were greatly improved. Bio‐based SDE resin showed promise for optimizing carbon fiber composite interphase.