Epoxy Polymer Research Articles

Research on the wear resistance and impact resistance of modified rubberized concrete

Rubber can improve the ductility and durability of concrete and reduce compressive strength. Tests were conducted to investigate the mechanical properties, wear resistance, and impact resistance of modified rubberized concrete (MRC) by mixing basalt fibers (BF), curing agent, and epoxy resin mixture. The results showed that the epoxy polymer improved the flowability of the rubberized concrete. The BF changed the failure mode of the rubberized concrete and enhanced the mechanical properties. When the curing agent-epoxy resin ratio was 4:8, the wear rate of BF6E8C4 after 120 times was 4.59 kg/m2, which was 70.02% and 3.77% less than that of BF2E8C4 and BF4E8C4. The impact strength of BF6E8C4 was increased by 256% and 409% compared with the BF2E8C4 and BF4E8C4, respectively. By analyzing the mechanism of the synergistic modification of BF and epoxy polymer, it was found that the synergistic work of BF and epoxy polymer could make the internal structure of concrete denser. At last, the wear damage and impact damage models of MRC were established, and the coefficient of determination exceeded 0.92.

Fiber reinforcement of polymer hybrid sandwich composites using SNiPs: effect of silica nanoparticles on flexural and compressive strength

The increasing demand for lightweight, high-strength composite materials in aerospace, automotive, and structural applications has intensified research into polymer composites. To address the challenge of enhancing mechanical properties while maintaining weight efficiency, this study investigates the effect of silica nanoparticles (SNiPs) on the flexural and compressive strength of sandwich composites. These composites are constructed from fiber-reinforced carbon, para-aramid, glass, and polyurethane (PU) foam. Composite specimens with varying concentrations of SNiPs were produced using a hand layup process with synthetic fiber-reinforced polymer glass fibers (GFRP), carbon fibers (CFRP), para-aramid fibers (KFRP), urethane foam, and epoxy glue. Fabricated using a quasi-static stacking sequence technique, the composites feature a three-layer sandwich matrix(0 K 1 / 45° C 1 / 45° G 1/PU/ 45° G 1 / 45° C 1 /0 K 1). Flexural and compressive strength tests were conducted to assess their mechanical behavior. The results show that incorporating SNiPs into polymer hybrid sandwich composites significantly enhances both flexural and compressive strength. This improvement is attributed to the high aspect ratio and surface properties of SNiPs, which facilitate effective stress transfer between the reinforcing fibers and the polymer matrix. The flexural strengths achieved with 0, 2, 4, and 6 wt.% SNiPs were measured as 52.583, 58.713, 64.108, and 61.397 MPa, respectively. Similarly, the compressive strengths were measured as 2.207, 2.813, 3.528, and 3.182 MPa for the respective weight percentages.

Effect of crosslinking density on the self-healing and self-reporting properties of epoxy anti-corrosion coatings

This work developed a novel coating with self-healing and self-reporting performance by embedding polyurethane/poly-(urea-formaldehyde) (PU/UF) microcapsules in a shape memory epoxy polymer. 2’7’-Dichlorofluorescein (DCF) and linseed oil were applied as the coloring agent and healing agent, respectively, which are encapsulated into the PU/UF microcapsules (DL@PU/UF microcapsules) via a facile one-step method. To adjust the shape memory effect and the self-reporting performance of epoxy system, two kinds of curing agents (D230 and D400) were reacted with bisphenol A diglycidyl ether epoxy monomer to design a series of coating samples, finally the optimal coating system was selected by three indexes including barrier performance, residual amino content and coating hardness. When the composite coating was damaged, DCF can flow out of the broken microcapsules and react with the residual amino groups in the epoxy coating matrix, which can be recognized red signals in natural light and yellow fluorescent signals under ultraviolet light irradiation. More importantly, the excellent self-reporting property of the coating can be achieved on various metal substrates that broaden the application range of the coating. As for self-healing performance, the damaged coating can be healed quickly due to the shape memory effect of the coating as well as the filling of linseed oil in the scratched region. The Rct value of the healed coating containing 6 % DL@PU/UF microcapsules after immersing in 3.5 wt% NaCl solution for 5 days was more than 3 times that of the scratched coating, and the Rc value was about 16 times that of the scratched coating, indicating its corrosion protection performance. The novel coting not only achieve timely self-reporting ability of color and fluorescence, but also rapidly repair the coating damage, which is essential to practical applications.

Rapid repair and degradation: A study of high-performance recyclable vitrimer epoxy resin based on disulfide bonds

Petroleum-based epoxy resin is commonly used in electrical equipment due to its outstanding performance and affordability. However, its non-melting characteristics present challenges for recycling, leading to significant resource waste and environmental pollution. To address this issue, this study prepared and synthesized a kind of vitrimer epoxy resin polymer material based on disulfide bonds with 2,2′-Diaminodiphenyl disulphide as the curing agent. The research investigated the impact of the curing agent ratio on the resin's structure and properties. The resin was mechanically recovered through hot pressing at high temperature and pressure, and its chemical degradation and recovery were achieved via the reduction reaction of the thiol and disulfide bond. The findings revealed that a curing agent to epoxy group material ratio of 0.75 improved the resin system's electrothermal properties. The electrical insulation property retention rate after hot pressing recovery reached 95 %, with a mechanical property retention rate of 85 %. The disulfide bonds can be reoxidized and crosslinked to realize the recovery and reuse of vitrimer resin degradation solution. Vitrimer epoxy resin based on disulfide bonds is a significant way to realize the environmental protection of epoxy electrical equipment.

Chemical and Solvent‐Based Recycling of High‐Performance Epoxy Thermoset Utilizing Imine‐Containing Secondary Amine Hardener

AbstractEpoxy thermosets are indispensable in various industrial applications due to their exceptional material properties. However, their limited recyclability poses a significant challenge for sustainability. To address this issue, integrating recyclable imine moieties into epoxy systems has emerged as a promising strategy. Despite recent advancements, challenges persist concerning the hydrolytic stability of imine‐based epoxy thermosets and the formation of irregular oligomeric structures upon depolymerization. In this study, these shortcomings are solved by designing a liquid imine monomer with secondary amine functionalities, which is subsequently reacted with commercially available epoxy monomers to produce high‐performance epoxy thermosets. Remarkably, the developed imine‐based epoxy system shows no sign of hydrolysis even under high‐temperature aqueous conditions, underscoring its potential for various industrial applications. Only the treatment with aqueous HCl results in the selective formation of exclusively well‐defined molecules, in high isolated yields after depolymerization. Crosslinking these building blocks once again yields recycled polymers with properties identical to pristine material. Moreover, it is discovered that, despite the crosslinked nature of the epoxy thermoset, the complete dissolution of the intact polymer in dichloromethane allowed for simple solvent‐based recycling. Through design on the molecular level, the recycling of imine‐based epoxy polymers is achieved via chemical and solvent‐based techniques.

Toward the Manufacturing of a Non-Toxic High-Performance Biobased Epoxy-Hemp Fibre Composite.

This study describes the production of a new biobased epoxy thermoset and its use with long hemp fibres to produce high-performance composites that are totally biobased. The synthesis of BioIgenox, an epoxy resin derived from a lignin biorefinery, and its curing process have been optimised to decrease their environmental impact. The main objective of this study is to characterise the rheology and kinetics of the epoxy system with a view to optimising the composite manufacturing process. Thus, the epoxy resin/hardener system was chosen considering the constraints imposed by the implementation of composites reinforced with plant fibres. The viscosity of the chosen mixture shows the compatibility of the formulation with the traditional implementation processes of the composites. In addition, unlike BPA-a precursor of diglycidyl ether of bisphenol A (DGEBA) epoxy resin-BioIgenox and its precursor do not have endocrine disrupting activities. The neat polymer and its unidirectional hemp fibre composite are characterised using three-point bending tests. Results measured for the fully biobased epoxy polymer show a bending modulus, a bending strength, a maximum strain at failure and a Tg of, respectively, 3.1 GPa, 55 MPa, 1.82% and 120 °C. These values are slightly weaker than those of the DGEBA-based epoxy material. It was also observed that the incorporation of fibres into the fully biobased epoxy system induces a decrease in the damping peak and a shift towards higher temperatures. These results point out the effective stress transfers between the hemp fibres and the fully biobased epoxy system. The high mechanical properties and softening temperature measured in this work with a fully biobased epoxy system make this type of composite a very promising sustainable material for transport and lightweight engineering applications.

Bending shape memory properties and multi-scale viscoelastic behaviors of knitted-fabric reinforced polymer composites

Knitted fabrics with easily deformable loop structure have the potential in the development of shape memory polymeric composites with large recovery deformations. The knitted fabric reinforced shape memory epoxy polymer composites (SMPC) were prepared in this work. The effects of loop densities, orientations and bending radii on shape memory properties of SMPC were investigated. The shape fixity ratio and shape recovery ratio of SMPC subjected to U-shaped bending radius of 5 mm are above 98 %. The shape recovery force of SMPC can reach up to 5.9 N. The thermodynamic properties of SMP were also characterized to obtain mechanical parameters and a user-defined material subroutine (UMAT) of shape memory epoxy polymer (SMEP) was written. Based on viscoelastic theory and the multi-scale geometrical structures, the macroscopic homogeneous thermodynamic model and mesoscopic thermodynamic model of knitted fabric reinforced SMPC were established to study the macro-scale stress distribution and meso-scale deformation evolution during shape memory process, respectively. The neutral surface position of SMPC during bending deformation is offset inner. The unique anisotropic loop structure of knitted fabric determines the shape memory behavior of the SMPC. Finally, micro-CT characterizations of knitted fabric reinforced SMPC were conducted to further understand the loop deformation mechanism during shape memory process. This study will provide important theoretical and technical support for large deformation structure design and deformation prediction of smart composites.

Stretchable Thermoelectric Generators for Self‐Powered Wearable Health Monitoring

AbstractAs continuous wearable physiological monitoring systems become more ubiquitous in healthcare, there is an increasing need for power sources that can sustainably power wireless sensors and electronics for long durations. Wearable energy harvesting with thermoelectric generators (TEGs), in which body heat is converted to electrical energy, presents a promising way to prolong wireless operation and address battery life concerns. In this work, high performance TEGs are introduced that combine 3D printed elastomers with liquid metal epoxy polymer composites and thermoelectric semiconductors to achieve elastic compliance and mechanical compatibility with the body. The thermoelectric properties are characterized in both energy harvesting (Seebeck) and active heating/cooling (Peltier) modes, and examine the performance of wearable energy harvesting under various conditions such as sitting, walking, and running. When worn on a user's forearm while walking outside, the TEG arrays are able to power circuitry to collect photoplethysmography (PPG) waveform data with a photonic sensor and wirelessly transmit the data to an external PC using an on‐board Bluetooth Low Energy (BLE) radio. This represents a significant step forward on the path to sustainable body‐worn smart electronics.

Influence of polymer types on the performance of piezoelectric ceramic/polymer composite arrays based on 1–3 type structure

Piezoelectric ceramic/polymer composite array elements based on a 1–3 structure are widely used in high-frequency transducers. This study selected three commonly used polymers (epoxy resin, silicone rubber, and polyurethane) to prepare three types of piezoelectric ceramic/polymer composite array elements. These elements were tested using a concentric ring sampling scheme from the inside to the outside and analyzed through finite element simulation to explain the performance differences in piezoelectric ceramic/polymer composite arrays. The test results demonstrate that compared to composite arrays made with piezoelectric ceramic and epoxy resin or polyurethane, piezoelectric ceramic/silicone rubber composite arrays exhibit superior resonance characteristics and consistency. The resonance frequency fluctuation is within 6 kHz, with a maximum deviation factor of 1.22 %, and an average effective electromechanical coupling factor of up to 0.69. The experimental results also show significant performance differences between edge and non-edge elements, suggesting that in practical applications, edge elements of the array can be set as dummy elements to ensure array consistency.

Glass fibre hybridization to improve the durability of circular flax fibre reinforced composites with off-the-shelf recyclable polymer matrix systems for large scale structural applications

Natural fibre composites (NFCs) are not durable in the long run because of the susceptibility of natural fibres to environmental conditions and specifically moisture. Hybridizing NFC laminates externally, with synthetic fibre reinforcements, may improve durability, due to their inherent environmental resistance. This work aims to investigate the effects of glass hybridization, on flax fibre composites, studied via accelerated ageing. In specific, the durability of hybrid flax/glass fibre reinforced polymer composites, with two recyclable polymer matrices was investigated. Unidirectional (UD) flax and UD glass fibre reinforcements were employed to fabricate laminates, with two fully-recyclable off-the-shelf resin systems, as matrix: (i) a bio-based epoxy resin and (ii) an acrylic liquid thermoplastic (Elium®). In addition, a standard petroleum-based epoxy polymer matrix was for reference purposes. Weathering and hygrothermal ageing were used to test the durability of coupons, exposed to UV radiation/condensation/water spray environment (weathering ageing), and full-immersion in distilled water at 23, 40, and 60°C (hygrothermal ageing). In all cases, ageing was performed for a total duration of 56 days. The performance of the unaged and aged composite coupons was assessed and compared in terms of flexural and viscoelastic performance as well as SEM (Scanning Electron Microscopy) analysis. It was revealed that the addition of glass fibres with flax fibres in the hybrid composites improves the performance and better resistance against ageing environments than their neat flax fibre composites.

MATERIALS FOR IMPREGNATION OF POROUS METALLIZATION THERMAL SPRAYED ANTICORROSIVE COATINGS OF SUBMERSIBLE OILFIELD EQUIPMENT. Part 2

The use of thermal sprayed coatings in aggressive petroleum fluid is limited due to the presence of porosity in it. When fluid gets into the pores, corrosion processes begin and thereby reduce the protective properties of thermal sprayed coating. The application of impregnating compounds makes it possible to seal open porosity and prevent the penetration of aggressive environments into the metal under the coating, thereby increasing the barrier properties of the coating. Epoxy polymer materials demonstrate high corrosion resistance and are widely used in the oil industry to protect pipeline elements and submersible oilfield equipment during operation. The second part of the article presents both traditional polymer impregnation materials and new compositions with magnetic nanoparticles and nanocarbon fillers (fullerenes, graphene and nanotubes) which, due to the created magnetic field, are evenly distributed throughout the polymer matrix and increase the crack resistance of the matrix. Polymer impregnating materials of both domestic and foreign production based on phenolic, epoxy, acrylic and urethane resins, modes of their application, conditions of their operation and temperature restrictions are considered. The possibility of using existing independent anti-corrosion polymer coatings as an impregnation of metallization thermal sprayed layers is discussed. Their advantages and disadvantages are highlighted. Examples of self-healing polymer matrices are given that are capable of recognizing the onset of corrosion processes and responding by releasing appropriate effective self-healing agents. The possibility of adding inhibitors to the polymer matrix is described, which helps to increase the anti-corrosion properties of the coating and thereby increase the time between failures of equipment. The issue of normative regulation of the use of impregnating compositions in various fields of industry is covered. The main directions of research that need to be carried out to solve the problem of using polymer materials as the most promising impregnating compositions for anti-corrosion thermal sprayed coatings of submersible oilfield equipment have been identified. First of all, it is necessary to reduce the viscosity of polymer resins to increase their penetration into open pores.

In English

Biopolymer matrices has been synthesized on the basis of ED-20 epoxy resin and soybean oil (SbO) bearing cyclocarbonate and epoxy groups. Mono(cyanoethyl)diethylenetriamine (UP) and tris(2-hydroxyethyl)amine (TEA) were used as hardeners. Chemical structure, mechanical properties, thermo-oxidative resistance of the samples and their changes after contact with distilled water, alkaline or acidic environment were studied. By means of ATR-FTIR the possible formation of H-NIPU (hybrid non-isocyanate polyurethane) fragments between cyclocarbonate groups of SbO and amino groups of the hardener was demonstrated. Influence of the curing mode and the type of hardener on water absorption, chemical and thermal oxidation resistance of the developed biopolymer matrices was thoroughly investigated. UP-based biopolymer matrices showed water and alkali resistance similar to the ones of neat epoxy polymers, while TEA-based biopolymer matrices showed better resistance to the acidic medium. The thermo-oxidative stability of the chosen samples was revealed by the TGA method in an air atmosphere. It was demonstrated that epoxy polymer cured with TEA hardener were more stable than the one cured with UP hardener. The similar dependence is observed for biopolymer matrices based on TEA hardener. At the same time, the curing mode has almost no effect on ultimate tensile strength value of the samples with ED-20/UP composition. However, the addition of functionalized SbO to the epoxy matrix cured with both TEA and UP hardeners increases the ultimate tensile strength values regardless of the type of oil functionalization. As expected, all biopolymer matrices exhibited higher ultimate tensile strength compared with unmodified epoxy polymers, which provides the possibility of their further application to obtain multi-layered bioplastics.

Designing tribotechnical epoxy composite materials reinforced with chopped fibers and modified with silicon organic varnish

The object of research is modified epoxy composite materials containing fibrous fillers treated in physical fields. The technological features of the development of tribotechnical epoxy composites, which must withstand the effects of elevated temperatures, have been considered. In this case, it is necessary to modify the structure of the epoxy polymer matrix, which is achieved as a result of the introduction of heat-resistant organosilicon varnish. Organosilicon varnishes and chopped fibers contain technological additives, which complicates the process of structuring epoxy composites and leads to the appearance of structural defects. Removal of technological additives and cleaning the surface of the aramid and glass fibers from lubricants is possible as a result of processing the components of the composition in physical fields. There is a need to study the influence of physical fields on the structuring processes of the epoxy system and the formation of the structure of epoxy composites with specified properties. Modified epoxy composites contain chopped aramid and glass fibers treated with ultrasound. The tribotechnical characteristics of epoxy composites were studied at a sliding speed of V=1.0 m/s with a change in specific load from 0.5 MPa to 1.5 MPa. The temperature in the tribocontact zone during frictional interaction rises to 100 °C with an increase in the specific load. An increase in the density of the surface layer of tribocontact of epoxy composites with fillers treated in physical fields was revealed. The practical recommendations have been compiled for the implementation of the treatment technology of components in physical fields, which ensures structuring of epoxy composites with high tribotechnical characteristics

LUNAR: Automated Input Generation and Analysis for Reactive LAMMPS Simulations.

Generating simulation-ready molecular models for the LAMMPS molecular dynamics (MD) simulation software package is a difficult task and impedes the more widespread and efficient use of MD in materials design and development. Fixed-bond force fields generally require manual assignment of atom types, bonded interactions, charges, and simulation domain sizes. A new LAMMPS pre- and postprocessing toolkit (LUNAR) is presented that efficiently builds molecular systems for LAMMPS. LUNAR automatically assigns atom types, generates bonded interactions, assigns charges, and provides initial configuration methods to generate large molecular systems. LUNAR can also incorporate chemical reactivity into simulations by facilitating the use of the REACTER protocol. Additionally, LUNAR provides postprocessing for free volume calculations, cure characterization calculations, and property predictions from LAMMPS thermodynamic outputs. LUNAR has been validated via building and simulation of pure epoxy and cyanate ester polymer systems with a comparison of the corresponding predicted structures and properties to benchmark values, including experimental results from the literature. LUNAR provides the tools for the computationally driven development of next-generation composite materials in the Integrated Computational Materials Engineering (ICME) and Materials Genome Initiative (MGI) frameworks. LUNAR is written in Python with the usage of NumPy and can be used via a graphical user interface, a command line interface, or an integrated design environment. LUNAR is freely available via GitHub.

Development of Foam Composites from Flax Gum-Filled Epoxy Resin

In the present work, an innovative range of foams based on flax gum-filled epoxy resin was developed, reinforced or not by flax fibers. Foams and composites with different gum and epoxy resin contents were produced and their mechanical and thermal performances were characterized. To enhance the organic flax gum filler’s cross-linking, we exploited the oxidized components’ reactivity with the amine hardener (isophorone diamine). We compared the materials obtained with those derived from the native components. The flax gum and fibers were primarily characterized by chemical analysis, NMR, and FTIR to evaluate the mild oxidation of the native materials. The formation of chemical bonds between the oxidized polymer chains, epoxy resin, and hardener was evidenced by FTIR, and the materials were then studied by SEM and X-ray computed micro-tomography (CT) and submitted to mechanical and thermal tests. The relevance of the oxidation treatment was highlighted through a significant increase in density and mechanical performance (+36% and +81%, respectively, for the 100% flax gum material). The positive effect of the flax fibers on homogeneity evidenced through micro-CT analysis was also clearly addressed. This set of promising results paves the way for the future development of fully flax-based insulation composite materials.

Influence of the processing parameters on the degradation of poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and modification of their molecular weight using chain extenders

Poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) exhibit valuable mechanical properties like high stiffness and tensile strength but are sensitive to processing parameters. The influence of these parameters was evaluated by measuring the variation of melt viscosity during processing. For all experiments, in the absence of chain extenders, the decrease in melt viscosity clearly showed the degradation of polymers during processing. This is more pronounced for PHBV than PLA. In order to compensate for the degradation and, if possible, improve the melt strength of these bio-based polymers, two chain extenders have been evaluated: dicumyl peroxide (DCP) and a polymeric epoxy acrylate chain extender (Joncryl® ADR 4400). DCP reacts quickly with PLA and PHBV, while the epoxy-acrylate chain extender shows slower kinetics. For the PLA, with both investigated chain extenders, an increase in the molecular weight as compared with the virgin polymer and eventually the apparition of an insoluble fraction due to branching and crosslinking are observed. In the case of PHBV, the degradation is compensated by using DCP, requiring short processing times. No significant increase in molecular weight was observed when using the polymeric epoxy acrylate chain extender, requiring longer residence times, although the apparition of a gel fraction suggests the presence of branching and crosslinking.

Synergistic effects of epoxy polymer and rejuvenator in asphalt rejuvenation: A comprehensive performance analysis

Epoxy asphalt mixtures are renowned for their exceptional road performance. In this study, the simultaneous application of a rejuvenator and epoxy polymer in asphalt rejuvenation, comparing it with using only epoxy polymer were explored. Approaches were evaluated from the perspectives of tensile performance, low-temperature performance, viscosity properties, microscopic phase morphology, and molecular structure. Results reveal that the addition of the rejuvenator enhances the tensile toughness of the aged asphalt-epoxy system while significantly reducing viscosity under identical temperature and curing conditions. Microscopic analysis indicates that the rejuvenator weakens the uniformity of the dispersed phase, resulting in a less tightly interlocked structure between aged asphalt and the epoxy system. Molecular simulations demonstrate that the compatibility of aged asphalt with the rejuvenator and epoxy system is comparable to that of aged asphalt and the epoxy system alone. Furthermore, a small amount of rejuvenator increases the conversion degree of the epoxy system, whereas an excessive amount inhibits the curing reaction. These findings not only shed light on the mechanisms underlying rejuvenated epoxy asphalt systems but also hold promise for enhancing the competitiveness of such systems throughout their service life cycle.

Copper metallization of carbon fiber-reinforced epoxy polymer composites by surface activation and electrodeposition

The application of polymer metallization in lightweight and high-strength materials for the sporting goods, automotive, aerospace and construction sectors has attracted considerable attention. The present study aims to deposit a thin, uniform copper (Cu) layer on an epoxy‑carbon fiber (epoxy-Cf) composite material for lightweight, high-frequency radio reflector applications (Ka-Band and higher frequencies) required in space missions. In this work, a surface-activated electroplating technique in which the surface of the substrate is activated with a Sn/Ag system, followed by conventional electroplating is studied. Surface activation deposits layers of conducting metal ions on the surface of the epoxy-Cf composite, which significantly improves the electrical conductivity of the composite surface. The subsequent electrodeposition takes place from a CuSO4 solution with a pH value of 4 at three different current density values of 0.05 A/dm2, 0.5 A/dm2 and 1 A/dm2. The presence and abundance of metallic Cu over epoxy-Cf composite were confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The morphology and elemental composition of the coating were characterized by scanning electron microscopy equipped with energy dispersive spectroscopy. With current density and coating thickness, morphology of the deposit changed from cauliflower-like to spherical along with grain refinement. Microhardness test shows a hardness of 330 HV and the pull-off adhesion test gave a bond strength of 1.69 MPa for 27.56 μm thick copper deposit. A major challenge encountered during the deposition of Cu is the oxidation of the metal followed by immediate tarnishing. This issue has been effectively addressed by employing benzotriazole solution as a protective agent.

Epoxy Polymers Containing Metal–Organic Framework-Derived Layered Double Hydroxide and Black Phosphorus for Fire Resistance, Smoke Suppression, and Wear Resistance

Epoxy Polymers Containing Metal–Organic Framework-Derived Layered Double Hydroxide and Black Phosphorus for Fire Resistance, Smoke Suppression, and Wear Resistance

Evaluating the bonding effectiveness of CFRP patches in strengthening concrete structures

This study offers a thorough analysis of the efficiency of adhesively bonded Carbon Fiber-Reinforced Polymer (CFRP) patches in reinforcing concrete structures. In the dynamic field of civil engineering and infrastructure maintenance, utilizing modern materials and innovative techniques is crucial. Given the diverse stresses on concrete structures, sustainable reinforcement strategies like CFRP patching are vital. CFRP patches, with their high tensile strength and lightweight properties, reinforce concrete, enhancing its load-bearing capacity. The study reviews extensive literature on CFRP use, emphasizing its effectiveness in various environments. However, prevailing analyses often overlook shear-induced failures at the interface of bonded CFRP patches. To address this, the study introduces a novel fracture analytical technique, consolidating material parameters for assessing CFRP patch bonding efficiency. Experimental investigations compare epoxy, polyurethane, and silyl-modified polymers under mode-I loading conditions, revealing performance variations. The study underscores the importance of adhesive selection, advocating for a balance between strength and fracture energy absorption for optimal CFRP patch performance in concrete structures. It urges future design applications to consider these findings for enhanced selection and application of CFRP patches.