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Introduction: Root canal sealing materials play a crucial role in an endodontic procedure by forming a bond between the dentinal walls and the gutta-percha. The current study aims to analyse the dentinal tubule penetration and adhesive pattern, including the push-out bond strength of six commercially available root canal sealers., Methodology: Eighty-four mandibular first premolars were split into seven groups (and n = 12), Group 1: Dia-Root, Group 2: One-Fil, Group 3: BioRoot RCS, Group 4: AH Plus, Group 5: CeraSeal, Group 6: iRoot SP, Group 7: GP without sealer (control). Two groups were made, one for dentinal tubule penetration and the other for push-out bond strength; the total sample size was one hundred sixty-eight. Root canal treatment was performed using a method called the crown down technique, and for obturation, the single cone technique was used. A confocal laser scanning microscope (Leica, Microsystem Heidel GmbH, Version 2.00 build 0585, Germany) was used to evaluate dentinal tubule penetration, and Universal Testing Machine was utilised to measure the push-out bond strength (Shimadzu, Japan) using a plunger size of 0.4 mm and speed of 1mm/min. Finally, the adhesive pattern of the sealers was analysed by HIROX digital microscope (KH-7700). Statistical analysis was carried out by a one-way Anova test, Dunnet's T3 test, and Chi-square test., Results: Highest dentinal tubule penetration was noticed with One-Fil (p<0.05), followed by iRoot SP, CeraSeal, AH Plus, Dia-Root also, the most negligible value was recorded for BioRoot RCS. Meanwhile, BioRoot RCS (p<0.05) demonstrated the greater value of mean push-out bond strength, followed by One-fil, iRoot SP, CeraSeal, AH Plus and Dia-Root. Regarding adhesive pattern, most of the samples were classified as type 3 and type 4 which implies greater sealing ability and better adherence to the dentinal wall. However, BioRoot RCS revealed the most type 4 (p<0.05), followed by AH Plus, One-Fil, CeraSeal and Dia-Root., Conclusion: The highest dentinal tubule penetration was shown by One-Fil compared to other groups. Meanwhile, BioRoot RCS had greater push-out bond strength and more adhesive pattern than other tested materials., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Karobari et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Sustainable biomass resources are favored by researchers on account of their biodegradability and biocompatibility, which is a replacement for non-renewable fossil fuels. The development of low-carbon, green, and high-value bio-based adhesives are the inevitable trend of the industry development. However, the main factors limiting their application are poor water resistance and low bonding performance. Herein, the crosslinking network was constructed based on the reaction between the epoxy groups of trimethylolpropane glycidyl ether (TMPEG) and the amino groups of the synthesized aminated cellulose (AC) to form an interlocking bond. Through the synergy of covalent bond, electrostatic interaction, and hydrogen bond, the bonding strength and water resistance of the proposed adhesive can be effectively improved. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and solid-state nuclear magnetic resonance spectroscopy ( 13 C NMR) demonstrated the formation of epoxy-amine network. The excellent bonding strength and water resistance of the adhesive made with AC and TMPEG (AC-TMPEG) are mainly reflected by the dry lap shear strength of 2.56 MPa and the wet lap shear strength of 1.94/2.09 MPa after soaking in 63 °C/boiling water for 3.0 h. This study reveals an approach for manufacturing wood adhesive with superior bonding performance and exceptional water resistance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

This work analyses the fatigue delamination and fracture stress behaviour under mode I of adhesive joints made on an epoxy matrix composite material with unidirectional carbon fibre reinforcement and a commercial epoxy-based adhesive. DCB type tests (for mode I) were used with the aim to quantify the influence of the period of exposure to a degradation process in a salt spray chamber, to which the tested samples were subjected, on their fatigue behaviour. For this purpose and after a previous static characterisation of the material in which the critical values of the energy release rate for different exposure periods were determined, the levels of the energy release rate to be applied in the fatigue tests and the exposure periods to be considered (no exposure, exposure during one week and twelve weeks) and a ratio of fatigue stress levels of R = G min /G max  = 0.1 were defined. From this experimental data, the G-N fatigue initiation curves and the G-da/dN growth curves were obtained. The experimental data obtained, in the fatigue initiation phase of the delamination process, have been treated by means of a probabilistic model based on a Weibull distribution, the application of models of these characteristics has allowed a better interpretation of the experimental results obtained. The most relevant result of the work is that, in general, the fatigue limits obtained for the adhesive joint, under mode I fracture, when subjected to a degradation process in a saline environment, do not translate into a relevant loss of its resistance capacity against this fatigue delamination phenomenon, in its initiation phase. On the other hand, the crack growth rates of the material subjected to different periods of exposure to a saline environment are similar and higher than those obtained for the material without exposure., (© 2022. The Author(s).)

Biobased epoxy-derived raw materials will be essential for future coating and adhesive designs in industry. Here, a facile approach is reported towards the incorporation of limonene into an epoxy-functionalized polycarbonate and its crosslinking with a polyamine curing agent to obtain a thermoset material. For the first time, a solvent-borne adhesive with excellent film-forming, mechanical and adhesion strength properties is described., (© 2022 Wiley-VCH GmbH.)

Water-resistant and high-strength adhesion on different surfaces has attracted considerable attention for decades. However, the adhesion performances of conventional adhesives suffer from deterioration in adhesion performances under water or wet conditions. This work proposes a dipole-dipole interaction strategy for fabricating a solvent-free adhesive that is synthesized via simple one-step copolymerization of dipole monomer acrylonitrile (AN), crosslinker poly(ethylene glycol) diacrylate (PEGDA) with variable length, and a monomer-soluble initiator that initiates room-temperature polymerization. The dipole-dipole interactions from cyan groups in AN concurrently contribute to strong cohesion and adhesion strength in bonding to a wide range of substrates including aluminum, ceramic, glass fiber, epoxy resin, polyethylene terephthalate, wood, and fractured large segmental bone. The adhesion strengths are dependent upon the length of PEGDA, and the shorter PEGDA-crosslinked PAN adhesive demonstrates outstanding water-resistant adhesion spanning pH 2 to pH 10 for 30 days with adhesion strength ranging from 3.31 to 3.97 MPa due to strong dipole-dipole pairing shielding. This dipole-dipole interaction and co-dissolution strategy open a new avenue for creating high-strength water-resistant adhesives for promising applications in engineering and hard-tissue repair., (© 2021 Wiley-VCH GmbH.)

Improving the environmental performance of resins in wood treatment by using renewable chemicals has been a topic of interest for a long time. At the same time, lignin, the second most abundant biomass on earth, is produced in large scale as a side product and mainly used energetically. The use of lignin in wood adhesives or for wood modification has received a lot of scientific attention. Despite this, there are only few lignin-derived wood products commercially available. This review provides a summary of the research on lignin application in wood adhesives, as well as for wood modification. The research on the use of uncleaved lignin and of cleavage products of lignin is reviewed. Finally, the current state of the art of commercialization of lignin-derived wood products is presented.

Objectives: Epoxy adhesives contain organic solvents and are widely used in industry. The hazardous effects of epoxy adhesives remain unclear. The objective of this study was to investigate the risk of hearing loss among workers exposed to epoxy adhesives and noise., Design: Cross-sectional study., Methods: For this cross-sectional study, we recruited 182 stone workers who were exposed to both epoxy adhesives and noise, 89 stone workers who were exposed to noise only, and 43 workers from the administrative staff who had not been exposed to adhesives or noise. We obtained demographic data, occupational history and medical history through face-to-face interviews and arranged physical examinations and pure-tone audiometric tests. We also conducted walk-through surveys in the stone industry. A total of 40 representative noise assessments were conducted in 15 workplaces. Air sampling was conducted at 40 workplaces, and volatile organic compounds were analysed using the Environmental Protection Agency (EPA) TO-15 method., Results: The mean sound pressure level was 87.7 dBA (SD 9.9). The prevalence of noise-induced hearing loss was considerably increased in the stone workers exposed to epoxy adhesives (42%) compared with the stone workers who were not exposed to epoxy adhesives (21%) and the administrative staff group (9.3%). A multivariate logistic regression analysis revealed that exposure to epoxy adhesives significantly increased the risk of hearing loss between 2 and 6 kHz after adjusting for age. Significant interactions between epoxy adhesives and noise and hearing impairment were observed at 3, 4 and 6 kHz., Conclusions: Epoxy adhesives exacerbate hearing impairment in noisy environments, with the main impacts occurring in the middle and high frequencies., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

The present communication deals with a technique developed for the selective staining of neural tissue in thick (10 micron) Epon sections. A new adhesive method was needed, because the known techniques are only applicable to 0.5-2 micron thin sections. The critical step in the procedure is the adhesion of the sections onto the slides. This is accomplished by heating the sections on top of a uniform layer of albumin glycerol on the slide followed by coating with celloidin. The results after deplasticizing and coagulation with this technique are comparable to those obtained by paraffin or frozen section techniques, but in addition have the advantage of Epoxy resin embedding e.g. the possibility of cutting undecalcified hard tissues and sections for serial reconstruction.

Until recently use of adhesives was confined to cases in which glued areas could be pre-treated or at least cleaned. Thus, grease or oil contaminated surfaces could not be joined together by glueing. More recently, some adhesives have been developed which allow previous treatment of greasy surfaces to be avoided. Among these we find epoxy resins, acrylics and polyurethances. These adhesives have been used until now in various industries. We have begun a research program with these products and in aiming to design an adhesive which would enable immediate and strong bone bonding and avoid problems of metallic fixation, this study is a continuation of our previous research. Thus we tested - currently available surgical and dental adhesives - original mixtures developed in our laboratory. Mechanical assays were performed on bone samples from human femurs in different conditions : dried, cleaned, fresh, or after immersion in physiological solution. They consist essentially of tensile tests on Lhomargy and Zwick's machine wherein the stress is directed perpendicular to the interface. Variations of tensile strength (in h bar) are related to hardening time and to mixture composition. The specimens are joined together either in monolayers or in multilayers. The use of adequate catalysts ensures setting at room temperature. Torsion tests and fatigue tests are carried out concomitantly. Standardized bevel fermoral osteotomies were performed on mice with a dental saw after I.P. Nembutal anesthesia in order to test biological tolerance : - for the control group we study the evolution of bone repair after circumferential wiring - for the animals under test, bones are glued together with one of the proposed adhesives. Radiological and histological studies (using classical Azantrichrome staining after demineralization) are carried out at regular time intervals. In the control animals particular attention is paid to the time course of the formation, constitution and evolution of callus. In the test animals, we can observe callus formation, bone growth into the adhesive material and glue resorption, and look for specific antigenic phenomena. Despite expected improvements, bone glueing remains a challenge and only restricted clinical applications can be proposed.

The fatigue of adhesive joints in offshore wind turbine blades is a critical and widespread challenge, necessitating an urgent focus on adhesive bond reliability. Given the constraints of full-scale testing, this research explores the fatigue endurance of carbon fiber–epoxy adhesive composites, integral to blade construction. Recognizing the fatigue characteristics' sensitivity to environmental factors and joint dimensions, an innovative approach to fatigue modelling and evaluation is introduced. This method incorporates the influence of different environmental stresses and size effects. Specifically, a degradation coefficient and size impact factor (SIF) are introduced into the cyclic cohesive zone model, and a simulation-based analytic approach is proposed for analyzing adhesive fatigue. Furthermore, we introduce a reliability modelling procedure that integrates performance degradation theory to address the deteriorative characteristics inherent in adhesive fatigue. Subsequently, the specimens' damage accumulation increased by 75% because of the stresses and escalated to 85% with adhesive joint size effects, causing carbon fiber Reinforced Polymer/epoxy adhesive joints to fail interfacially rather than in a mixed-mode manner. This study provides valuable insights for the safety analysis and assessment of adhesive joint performance in offshore wind turbine blades. [ABSTRACT FROM AUTHOR]

[Display omitted] Thermoset epoxy resin-based materials are widely used, but their permanent cross-linked network limits their processability and reusability, which can lead to environmental burdens. In this work, by exploiting the weak reactivity of aniline to design appropriate reaction ratios, we achieved a linear link between the epoxy resin and the curing agent. This linear link, along with the crosslinking points provided by the flexibly branched polyurethanes, avoids the inherent brittleness associated with the highly crosslinked network of conventional epoxy resins. As a result, the adhesive exhibits extraordinary improvements in extensibility and toughness. The lap shear strength, tensile strength and elongation at break reach 11.9 MPa, 14.4 MPa and 607 %, respectively. The fracture toughness is as high as 109.6 kJ/m2, far beyond the existing epoxy adhesives. The synergistic effect of disulfide bonds and hydrogen bonds confers the adhesive with self-healing and repeatable bonding characteristics. The multi-level hydrogen bonding and appropriate phase separation structure are key to optimizing toughness, resulting in excellent comprehensive performance. The introduction of polyurethane not only improves toughness but also enhances the interfacial bonding force between the adhesive and the substrate, broadening the scope of applications. The prepared high-performance polymers provide new insights into reusable epoxy adhesives. [ABSTRACT FROM AUTHOR]

Base isolators, traditionally made from natural rubber reinforced with steel sheets (SERIs), mitigate energy during seismic events, but their use in developing countries has been limited due to high cost and weight. To make them more accessible, lighter, cost-effective reinforcement fibers have been utilized. Additionally, the increasing use of natural rubber has caused waste storage and disposal issues, contributing to environmental pollution and disease spread. Exploring recycled rubber matrices as alternatives, this study improves seismic isolators' mechanical properties through modified reinforcements and layer adhesion. Eight reinforcement materials and eight adhesives, which may be activated with or without heat application, are systematically evaluated. Employing the chosen reinforcements and adhesives, prototypes are tested mechanically to examine their vertical and horizontal performance through cyclic compression and cyclic shear testing. Two innovative devices using recycled rubber matrices were developed, one using a layering technique and another through a monolithic approach shaped with heat and pressure. Both integrate a fiberglass mesh reinforced with epoxy resin; one employs a heat-activated hybrid adhesive, while the other uses a cold bonding adhesive. These prototypes exhibit potential in advancing seismic isolation technology for low-rise buildings in developing countries, highlighting the viability of recycled materials in critical structural applications. [ABSTRACT FROM AUTHOR]

In this work, a film adhesive comprised of oxazolidone modified epoxy novolac resin is analysed for its rheo-kinetic and thermodynamic behaviour under both isothermal and non-isothermal condition using rheometer at the time of curing. The study also includes finding out the effect of thermoplastic toughening agent polyethersulfone (PES), on its rheo-kinetics and thermodynamics. Various kinetic parameters are derived using Kamal and Kissinger equation for isothermal and non-isothermal condition, respectively. Subsequently, the rate constants obtained from this study are used to compute the thermodynamic parameters for the activated state complex via absolute reaction rate theory proposed by Eyring. [ABSTRACT FROM AUTHOR]

Controlling hybrid material properties by simple monomer design offers an elegant pathway to prepare thermoset adhesives with tunable properties. Herein, biobased hybrid polyhydroxyurethane/polyepoxy is prepared starting from partially carbonated cashew nut shell epoxy derivatives (NC514) and m‐xylene diamine (MXDA). The curing reactions, that is, epoxy‐amine and cyclic carbonate aminolysis, monitored by ATR‐IR spectroscopy at 50 °C are found to be concomitant yielding highly homogeneous materials. Hybrid networks are extensively characterized by swelling tests, TGA, DMA, DSC, tensile tests, rheology, and lap‐shear‐test on aluminum substrates. The introduction of hydroxyurethane moieties within the epoxy‐amine networks enhanced the adhesion properties (up to 20% compare to neat epoxy resins) by combining hydrogen bonding capability and vitrimeric properties (thermoset able to flow). Rheological characterizations and reprocessing tests demonstrated that hybrid adhesives with up to 47 mol% of cyclic carbonate groups are capable of covalent exchange (internally catalyzed by tertiary amine) while keeping similar thermomechanical properties and enhanced adhesion strength compare to the permanent epoxy network. [ABSTRACT FROM AUTHOR]

This article explores the impact of Graphene Nanoplatelet (GNP) reinforcement on the mechanical and thermomechanical properties of epoxy adhesive. The impact of GNPs on the structural adhesive largely depends on factors like dispersion stability and GNP concentration. Given the complexity of these interactions, it is imperative to obtain indicators for the degree of each interaction. In this study, Pearson correlation matrix and heatmaps analysis were used to analyze the relationship between various variables and the strength of the connection. The addition of GNP at various concentrations to the epoxy adhesive led to a reduction in storage modulus, loss modulus, and glass transition temperature, attributed to the agglomeration of GNP. In bulk specimens, the incorporation of GNP, regardless of its content, has decreased tensile stress up to 70.7% while increasing its fracture elongation up to 396.3%. Within joining specimens with GNP, specimens with 1.5 wt% GNP content showed the highest cohesive fracture mode and largest shear strength. Pearson correlation matrix and heatmaps have demonstrated very good accuracy in reflecting the experimental data. They offer a comprehensive assessment of the relationship between various variables while indicating the degree of influence each variable has on the properties of the adhesive and joining specimens. Highlights: GNP effects in adhesive can be accurately analyzed with Pearson correlation matrix & heatmaps.Connections strength for various variables can be shown by Pearson correlation matrix & heatmaps.Pearson correlation matrix & heatmaps assess variable relationships comprehensively. [ABSTRACT FROM AUTHOR]

Heat shrink sleeves (HSS) are multilayer polymers that provide corrosion resistance for welding joints of steel pipes. Within the HSS structure, the adhesive layer is a blend of components, such as ethylene vinyl acetate (EVA) and linear low‐density polyethylene (LLDPE). In this study, a systematic approach was employed to investigate the effect of the rheology and blend composition of the maleic anhydride‐modified EVA and maleic anhydride‐modified LLDPE (EVA‐g‐MA/LLDPE‐g‐MA) adhesive layer, prepared by melt processing, on its adhesion properties. Various characterization techniques were employed to investigate the local morphology of the prepared blends at different zones. Peel strength tests were used to characterize the adhesion strength of the prepared adhesives. Our findings demonstrate that the local distribution of EVA‐g‐MA within LLDPE‐g‐MA plays a crucial role in the adhesion strength of the adhesive. The results show that the adhesion strength enhanced by nearly 45% as the composition of EVA‐g‐MA at the surface went up by 20%, shifting the failure location from the epoxy/adhesive interface to the bulk of the adhesive layer. Our hypothesis of the decrease of EVA‐g‐MA intrachain bonding and increase in the EVA‐g‐MA free chain amount in the presence of LLDPE‐g‐MA to improve the adhesion properties was corroborated through our calorimetry results where the relative EVA‐g‐MA crystallinity decreased as LLDPE‐g‐MA was introduced to the blend. The findings of our study highlight the importance of rheological behavior and blend composition in obtaining optimized performance of adhesives within the HSS structure. Highlights: Compression molding of EVA‐g‐MA/LLDPE‐g‐MA induces a layered morphology.Local distribution EVA‐g‐MA/LLDPE‐g‐MA components influence their adhesion.EVA‐g‐MA at the interface improves the adhesion of EVA‐g‐MA/LLDPE‐g‐MA.LLDPE‐g‐MA suppresses the EVA‐g‐MA crystallinity.EVA‐g‐MA/LLDPE‐g‐MA composition affects adhesion at different temperatures. [ABSTRACT FROM AUTHOR]

Studying multiple properties of a material concurrently is essential for obtaining a comprehensive understanding of its behavior and performance. However, this approach presents certain challenges. For instance, simultaneous examination of various properties often necessitates extensive experimental resources, thereby increasing the overall cost and time required for research. Furthermore, the pursuit of desirable properties for one application may conflict with those needed for another, leading to trade-off scenarios. In this study, we focused on investigating adhesive joint strength and elastic modulus, both crucial properties directly impacting adhesive behavior. To determine elastic modulus, we employed a non-destructive indentation method for converting hardness measurements. Additionally, we introduced a specimen apparatus preparation method to ensure the fabrication of smooth surfaces and homogeneous polymeric specimens, free from voids and bubbles. Our experiments utilized a commercially available bisphenol A-based epoxy resin in combination with a Poly(propylene glycol) curing agent. We generated an initial dataset comprising experimental results from 32 conditions, which served as input for training a machine learning model. Subsequently, we used this model to predict outcomes for a total of 256 conditions. To address the high deviation in prediction results, we implemented active learning approaches, achieving a 50% reduction in deviation while maintaining model accuracy. Through our analysis, we observed a trade-off boundary (Pareto frontier line) between adhesive joint strength and elastic modulus. Leveraging Bayesian optimization, we successfully identified experimental conditions that surpassed this boundary, yielding an adhesive joint strength of 25.2 MPa and an elastic modulus of 182.5 MPa. [ABSTRACT FROM AUTHOR]

Epoxy film adhesives are typically used in different industries. However, these adhesives suffer from brittleness, low flexibility, and thermal stability problems. In this research, phenolic resin (Novolac) and poly (butyl acrylate‐block‐styrene) were used in the formulation of epoxy film adhesive (Diglycidyl ether bisphenol A) to increase thermal stability and adhesion strength and as the toughening agent, respectively. Alumina nanoparticles were also employed to enhance the mechanical properties. The influence of block copolymer and alumina nano particles was also assessed on the mechanical and thermal properties of epoxy‐based film adhesives. The investigation of the mechanical properties of dumbbell‐shaped samples and adhesion strength of the Al‐Al bonded joints were evaluated by tensile, lap shear, and T‐peel tests. The thermal stability of the optimal samples was assessed by thermogravimetry analysis (TGA). SEM analysis was also utilized to study the toughening mechanism. Tensile test of the dumbbell‐shaped samples indicated that the incorporation of 2.5 phr block copolymer and 2 phr alumina nanoparticles enhanced the toughness to 250%. The shear and peel strengths of this sample also exhibited 51% and 76% increase, respectively, showing a remarkable synergistic effect. On the other hand, TGA results revealed that the incorporation of block copolymer improved the thermal stability of the adhesive matrix. The copresence of these two materials also showed a considerable synergistic effect on the thermal stability. The SEM results were also in line with the results of mechanical tests as the crack deviation, crack pinning, and debonding were the most important mechanisms of toughening. Highlights: A new platform was developed for designing epoxy films adhesives with high mechanical, adhesion, and thermal properties.The hybrid of butyl acrylate block styrene copolymer, phenolic resin, and alumina nanoparticles showed synergistic effects on the lap shear and T‐peel strength.The greatest improvement in toughness was related to the epoxy adhesive containing 2.5 phr block copolymer and 2 phr alumina nanoparticles.Analysis of the fracture surface showed that by using hybrid of nanoparticles and block copolymers in the epoxy film adhesive formulation, the cohesive failure occurred.The use of hybrid additives in film adhesive formulations enlightened manufacture of adhesives for future studies on adhesive formulations. [ABSTRACT FROM AUTHOR]

We know that use, of Concrete is at construction industry is one of important part and comes at first number due to its compressive test, strength and durability. It has capacity to act as a binding material and high capacity to take strength and some other properties. There are many research were going on respective bond of concrete, fatigue, and creep on active level. Another part is as the times goes the strength of concrete will be reduced and may leads to damage and deteriorate it is one of the drawback of the concrete after we should have the need to repair the concrete to increase a structural strength and make a stiffness property improved which leads to safe structure. Our day by day infrastructure has been developed and have facing some problem for bonding between old to new structure and with composite structure are main issue so we need to repair that and make a proper strength to the corresponding structure. A bond which is good helps the engineer to consider monolithic behavior and it also helps in preventing de-icing salts and water to transmit along the interface. The strength and efficiency of a structure Increases with monolithic behavior of the structure. Main concept is the repair is to be done in such a way that bond will acts a it is originally designed. Making bond strength capable to transfer load and forces such as compression, tension, shear will be properly and safely. In concrete patch repairs application we have seen that the repair material plays a vital importance for concrete on Good Adhesion. For determining the bond strength between material and substrate there are several test. Bond strength under combines shear and compressive stresses, bond strength under shear stresses, under tension stresses respectively are the tests. Combine state of stress that combines compression and shear fall under slant shear tests. . In slant shear test we use a cylindrical or a square prism sample made of two identical parts which are bond at an angle of 30° and under axial compression they are tested. Some experimental work is done in this thesis using concrete steel composite material using epoxy based bonding agent and performing slant shear test and finding out bonding strength and durability of the bond. [ABSTRACT FROM AUTHOR]

In this research, a comprehensive comparison of the effects of adding nanomaterials on mechanical behavior of structural adhesive was experimentally investigated. The nanomaterials, namely graphene nanoplatelets (GNPs), Multi-Walled Carbon Nanotubes (MWCNTs), and reduced graphene oxide (RGO) were introduced at varying weight fractions of 0.25, 0.5, 0.75, and 1 wt% within the host adhesive. In addition to the parameters of type of nanomaterial and weight fraction, the effect of nanomaterial functionalization was also included. Two types of primary functionalization: carboxyl (COOH) and amine (NH2) along with non-functionalized filler was utilized. The nanomaterials were mixed in a high viscous structural adhesive araldite® 2011 by following a comprehensive mixing method. Flat doge bone specimens were prepared according to ASTM standard and subjected to testing using a universal testing machine (UTM). The results of the experimentation showed that the mechanical behavior of epoxy adhesive is significantly influenced by the addition of any type carbonaceous nanomaterial (GNPs, MWCNTs, and RGO) in the study, however, significant variation in mechanical properties (Elastic Modulus, Tensile Strength, Failure Strain, and Tensile Toughness), as well as their respective trends was observed among these nanomaterials. Overall, the introduction of GNPs was observed to increase the brittleness of the epoxy adhesive, whereas MWCNTs exhibited a contrasting effect by reducing brittleness. Moreover, it was found that the effect of functionalization and filler concentration on resulting properties was independent of each other. [ABSTRACT FROM AUTHOR]

In the manufacturing of optical products, precise adjustments are made to maintain the optical axis alignment of optical components, which are then securely positioned using adhesives. To achieve positional accuracy at the micron level, it is essential to comprehend the deformation of the adhesive joint over time during processing. This study focuses on investigating the displacement of optical components resulting from the deformation of a cationic photopolymerized epoxy adhesive, which cures under ultraviolet (UV) radiation. First, the conversion of the adhesive was formulated based on a curing reaction model. This conversion can be divided into three stages: the initial reaction during UV irradiation, the subsequent dark reaction, and the reaction induced by heating. Moreover, formulations were developed to describe changes in curing shrinkage, thermal expansion, and viscoelasticity in relation to the conversion. These equations, governing the adhesive properties, were then used to perform finite element method (FEM) simulations to analyze the position of the optical component. Experimental tests on adhesively bonded components were conducted under conditions identical to those employed in the simulation. Throughout the curing process of the adhesive, the optical component was continuously imaged using a coherence-scanning interferometer, enabling the quantification of its displacement from the acquired images. The results of the FEM simulation and experimental analysis exhibited a consistent trend, indicating the effectiveness of the modeling and simulation methods employed in this study. The majority of the displacement of the optical component occurred over several hours during the dark reaction stage, rather than during UV irradiation. Notably, the movement of the optical component was not limited solely to the thickness direction of the adhesive layer because of curing shrinkage but also extends to the in-plane direction because of the non-uniform distribution of the UV irradiation intensity. [ABSTRACT FROM AUTHOR]

This study improved laser shock-wave adhesion test (LaSAT) to evaluate the bonding strength of an aluminum alloy/epoxy resin adhesive, since the bonding strength is dependent on loading rate. In this method, strong shock wave due to laser ablation induces interfacial fracture, and the critical stress is computed using numerical simulations of the FEM. To accurately evaluate the bonding strength, the input waveform caused by laser ablation was identified for FEM computation. Such ablation impact (pressure vs. time) and its spatial distribution of ablation impact were experimentally investigated, and this study computed stress-wave propagation in the specimen. It is found that numerical simulation with FEM reproduced well the wave propagation. A wide range of loading rates was achieved by the quasi-static tensile test, split Hopkinson pressure bar (SHPB) test, and LaSAT. As a result, bonding strength exhibited a significant dependence on the strain rate, similar to that of bulk resin materials in general. [ABSTRACT FROM AUTHOR]

The study of materials for space exploration is one of the most interesting targets of international space agencies. An essential tool for realizing light junctions is epoxy adhesive (EA), which provides an elastic and robust material with a complex mesh of polymeric chains and crosslinks. In this work, a study of the structural and chemical modification of a commercial two-part flexible EA (3M™ Scotch-Weld™ EC-2216 B/A Gray), induced by 60Co gamma radiation, is presented. Combining different spectroscopic techniques, such as the spectroscopic Fourier transform infrared spectroscopy (FTIR), the THz time-domain spectroscopy (TDS), and the electron paramagnetic resonance (EPR), a characterization of the EA response in different regions of the electromagnetic spectrum is performed, providing valuable information about the structural and chemical properties of the polymers before and after irradiation. A simultaneous dissociation of polymeric chain and crosslinking formation is observed.The polymer is not subject to structural modification at an absorbed dose of 10 kGy, in which only transient free radicals are observed. Differently, between 100 and 500 kGy, a gradual chemical degradation of the samples is observed together with a broad and long-living EPR signal appearance. This study also provides a microscopic characterization of the material useful for the mechanism evaluation of system degradation. [ABSTRACT FROM AUTHOR]

This document provides a list of references to scientific articles and documents that explore various aspects of epoxy thermoset resins. The articles cover topics such as the curing behavior of thermosets, the dynamics of nanoparticles within polymer melts, the nanostructural heterogeneity of epoxy networks, and the effects of temperature on the fracture properties of epoxy systems. The articles utilize techniques such as X-ray photon correlation spectroscopy and molecular dynamics simulations to investigate the behavior and properties of epoxy resins. These resources offer valuable insights for researchers studying epoxy materials. [Extracted from the article]

Externally bonded strengthening technique to the concrete has been widely used with epoxy adhesive. However, the adhesive is considerably weak against high temperatures, which has been regarded as the critical point in the loss of integrity of the strengthened system. Alternatively, geopolymer materials have shown an excellent performance at high temperatures, thus, their potential to be used as adhesive material has been investigated in this work. In experimentation, the composite specimens were developed using both types of adhesives, epoxy and geopolymer, and their performance was evaluated at three temperature levels (20, 60, and 120°C) by conducting pull‐off strength tests and classifying their failure modes. It was observed that the strength of concrete and epoxy was reduced with temperature. In contrast, the strength of geopolymer‐based adhesives strength was increased due to the reactivity of the precursor at high temperatures. Also, bond strength was reduced for both composite specimens at elevated temperatures. The highest bond strength was observed for the epoxy‐based adhesive system at 20°C, and about 70% loss in bond strength was observed when exposed to 120°C. The failure mode was also shifted from concrete to adhesive interface failure, that is, failure between the adhesive and the fiber fabric layer. The geopolymer‐based adhesive system has lower strength than its counterpart at all temperature levels, and the failure mode was adhesive interface failure. To enhance the bonding capacity at high temperatures, efforts are being made by adding different minerals has been employed. From the experimental results, it was found that there were some improvements, however, it was still less than that of epoxy‐based system. Further optimization of the geopolymer adhesive using minerals is required and then high‐thermal resistance geopolymer adhesive can be established. [ABSTRACT FROM AUTHOR]

This study investigates the impact of marble powder as a part of fine aggregate and the addition of glass fiber on the bond strength of concrete and deformed high-strength post-installed steel rebars using the epoxy chemical as an adhesive. Five marble dust powder (MDP) substitution percentages (i.e. 0%, 10%, 20%, 30%, and 35%) and the addition of glass fiber (i.e. 0.5%, 1%, and 1.5%) were used. The performance of deformed high-strength post-installed rebars in conventional concrete and concrete modified with 35% marble powder and 1% glass fiber was examined here utilizing pull-out tests on a total of 96 specimens. To examine the bond behaviors of deformed high-strength post-installed rebars at the epoxy–conventional concrete interface and epoxy-modified concrete with MDP and glass fiber interface, test criteria included concrete compressive strength, anchorage depth of rebar into concrete, rebar diameter, and concrete cover to rebar diameter ratio. For post-installed high-strength deformed rebar, bond stress–slip relationships were determined, examined, and subsequently compared with prior work and readily available codes. It was found that none of the specimens exhibited pull-out failure and that the majority of them displayed concrete splitting, concrete rapture, or rebar rapture failure. This suggests that epoxy resins are particularly successful as bonding agents to retrofit concrete structures at the steel–concrete contact. A closed-form equation for predicting the bond strength for post-installed high-strength deformed rebar was also created using regression analyses on the experimental data. With a significant coefficient of determination (R2 = 0.85) the observed predicted bond strengths and the test data were quite similar. [ABSTRACT FROM AUTHOR]

Chitosan and bio-based epoxy resins have emerged as promising formaldehyde-free replacements for traditional urea–formaldehyde (UF) adhesives in engineered wood products. This study evaluated five chitosan-to-epoxy weight ratios (3:1, 2:1, 1:1, 1:2, 1:3) as adhesives for hot-pressing medium density fiberboards (MDF) using mixed hardwood fibers. Increasing the epoxy ratio reduced viscosity and gel time, facilitating spraying and fast curing. The density of the formulated MDFs increased with higher epoxy ratios, ranging from 679 kg/m3 for the 3:1 ratio to 701 kg/m3 for the 1:3 formulation, meeting the 500–900 kg/m3 density range specified in EN 323. The 1:3 epoxy-rich formulation enhanced modulus of rupture (MOR) to 31 MPa and modulus of elasticity (MOE) to 2392 MPa, exceeding the minimum requirements of 16 MPa and 1500 MPa set out in EN 310 and EN 316, respectively. Dimensional stability peaked at 5% thickness swelling for the 1:3 formulation after 24 h water soaking, fulfilling the < 25% requirement per EN 316. Internal bond strength reached a maximum of 0.98 MPa for the 3:1 chitosan-rich formulation, satisfying the 0.40 MPa minimum per EN 319. One-way ANOVA tests showed the adhesive ratio had a significant effect on mechanical properties and dimensional stability at 95–99% confidence levels. Duncan's multiple range test revealed the 1:3 ratio boards exhibited statistically significant improvements compared to untreated group. Overall, tailoring the ratios achieved well-balanced properties for MOR, MOE, and dimensional stability, demonstrating potential to replace UF resins. [ABSTRACT FROM AUTHOR]

The pull-out method was used to study the adhesive strength τ of "fiber–thermoset" systems with wide variations in area. Studied binders were based on resins that had different chemical natures (epoxy, epoxy phenol, orthophthalic, polyphenylsiloxane, and phenol–formaldehyde). Shear adhesive strength was determined for systems with two fiber types (glass and steel fibers). It was shown that strength τ depended on scale (area). Formation of τ occurred during the curing process and the system's subsequent cooling to the measurement temperature T. It was found that interface strength depended on measurement temperature across a wide temperature range that covered the highly elastic and the glassy state of the adhesive. The influence of residual stresses τres, acting at the "binder–fiber" interface, on the nature of the curves describing the dependence of the adhesive strength on the studied factor was experimentally shown. A qualitative explanation of the observed regularities is proposed. [ABSTRACT FROM AUTHOR]

In the rapidly developing microelectronics industry and technology, epoxy resin based electrically conductive adhesives must be urgently improved in terms of aging resistance, especially residual stress caused by thermal cycle aging. In this study, we investigated the stress behavior of rigid and flexible epoxy systems blended with bisphenol F epoxy (BPF) and fatty acid epoxy. The curing processes, thermal, and thermomechanical properties of the modified epoxy systems were assessed comprehensively. Moreover, the residual stress during the thermal cycle was monitored, and the bond strength was characterized. The results pointed out that by introducing soft molecular segments into a rigid system, the modified epoxy resin system had significantly lower residual stress values and exhibited a higher bond strength over a wider temperature range. Finally, we envision the systematic integration of residual stress testing with material strength testing for quantifying the bond failure of adhesive layers in the near future. [ABSTRACT FROM AUTHOR]

Several lignin-based adhesives were developed during the last decades. More recently, lignin isolation methods were improved, leading to technical grade lignins with constant properties. This recent scenario created the required conditions for the industrial use of lignin in adhesive applications, at large scale, with reliable properties. In this work, technical grade kraft lignin was epoxidized and incorporated in industrial epoxy resin, resulting into a partly biobased epoxy resin. Notwithstanding, the mechanical properties of cured partly biobased epoxy were investigated using Arcan device, aiming to reproduce realistic load conditions for the adhesively bonded joints. At last, failure envelopes were obtained from Drucker-Prager and von Mises models, revealing the most reliable model to calculate the failure prediction. Results pointed out to the development of a partly biobased epoxy adhesive with slightly superior mechanical properties, in comparison with industrial epoxy adhesive. Indeed, an important contribution was provided for the lignin revalorization and the mechanical characterization and failure prediction of epoxy adhesive based on the modified lignin. [ABSTRACT FROM AUTHOR]

The curing kinetics as well as the corresponding tensile properties of magnetocured epoxy adhesive doped with magnetic nanoparticles (MNPs) is investigated in this article, where the curing reaction process is depicted using an isoconversional model. It is found that the tensile modulus and strength strongly depend on the curing degree (CD) and mass fraction of MNPs when curing degree varies from 0.7 to 1.0. When curing degree is 0.7, the tensile modulus of the adhesive with 15%wt and 30%wt MNPs increases by 46% and 592% compared to that with 10%wt MNPs, respectively, but the increase is not obvious when curing degree is higher than 0.9. This difference is more significant in the tested tensile strength, where the samples with 15%wt and 30%wt MNPs are 7.08 and 20.83 times higher than the one with 10%wt MNPs under 0.7 curing degree. However, the corresponding tensile strength with 1.0 curing degree is reduced by 4% and 35%, respectively. Scanning electron microscopy observation reveals different fracture mechanisms caused by curing degree variation. Failure occurs in the adhesive region for curing degree below 0.9, while failure initiates and propagates at the interface between adhesive and MNPs for curing degree above 0.9. It can be concluded that the intrinsic property of the adhesive determines the tensile properties when the curing degree is lower than 0.9, while the weak interfacial interaction between adhesive and MNPs introduces reverse effect when the curing degree is higher than 0.9. This competitive relationship should be considered in the design of magnetocuring process. Highlights: Enhancement in adhesive modulus from MNPs addition degrades as CD approaches 1.Intrinsic property of adhesive determines the tensile strength with CD < 0.9.Weak interface dominates the failure mechanism in adhesive with CD > 0.9. [ABSTRACT FROM AUTHOR]

This work aims to characterize the water uptake mechanisms of a two-component epoxy adhesive joint immersed in deionized water. The pore-type defects in the bulk adhesive after the cure cycle are highlighted and characterized using X-ray µ-tomography. Two population patterns of defects are generated and analyzed, for two different thicknesses. The waterfront is not detectable by µ-tomography for this adhesive because the densities of the water and the adhesive remain relatively close to each other. Instead, the volume variation and kinetics of pore water filling have been accurately identified. This analysis was completed by optical observations and gravimetric measurements. [ABSTRACT FROM AUTHOR]

It is of great significance to design epoxy coatings with superior antibacterial properties and high adhesive properties, as well as excellent processing, superior durability, and high transparency. However, it is still a challenge because of the common complex design and synthesis. Herein, the bio-based monomer protocatechuic acid (PCA) was used as raw material, the catechol structure with high bonding and antibacterial properties was introduced into the flexible alkane segment of ethylene glycol diglycidyl ether (EGDE) through an efficient, and green method, and it was cured with isophorone diamine (IPDA) to prepare corresponding thermosets. The cured resins exhibited excellent all-around qualities, particularly in bonding and antibacterial. When 30% PCA was added to pure epoxy resin, the adhesion between substrate and coating increased from 4.40 MPa to 13.60 MPa and the antibacterial rate of coating against E. coli and S. aureus could approach 100%. All of this is due to the fact that the catechol structure present in PCA has the ability to interact with various substrates and alter the permeability of bacterial cell membranes. The architecture of this method offers a fresh approach to dealing with the issues of challenging raw material selection and complex synthesis techniques. [ABSTRACT FROM AUTHOR]

Dual-component epoxy resins are widely used for bonding different materials in automotive interior processing. However, due to the complexity and variability of automotive interior parts, uneven temperature distribution on curved surfaces during the thermoforming process can lead to uneven thermal stress distribution, damaging the interior components. This study focuses on addressing the damage issues caused by uneven thermal stress distribution during the thermoforming of automotive interior components. By monitoring the temperature and strain on the adhesive surface of the interior components during processing, using sensors and combining the readings with a finite element simulation, damage to the adhesive during processing was simulated. Based on this, a segmented thermoforming method for the model surface was employed, but it was found that this method did not significantly reduce the level of damage to the adhesive during application. Building upon the segmented simulation, significant results were achieved by applying temperature modulation at a certain frequency to adjust the damage of the interior components during processing. The techniques used in this study successfully reduced the unevenness of the adhesive surface temperature, improved the performance of the adhesive during application through segmented optimization and the application of ultrasound-assisted techniques, and markedly reduced the manufacturing process's energy consumption. [ABSTRACT FROM AUTHOR]

In this study, MIL‐101 (Cr) and NH2‐MIL‐101 (Cr) nanoparticles were synthesized by hydrothermal method. Butyl acrylate‐styrene copolymer was used along with these nanoparticles to improve the mechanical properties of epoxy adhesive. The results of the Fourier Transform Infrared (FTIR) and X‐ray diffraction (XRD) test showed that the synthesis and functionalization of the metal organic framework (MOFs) were successful. The mechanical properties and adhesion features in the lap joint bonding of aluminum foil to the aluminum foil of modified epoxy adhesives were investigated by tensile and lap shear tests. The results of the tensile test showed that by adding 0.3 wt% of NH2‐MIL‐101 (Cr) and 2.5 wt% of poly(butyl acrylate‐block‐styrene) to epoxy adhesive, the tensile strength, modulus and toughness of dumbbell samples were increased up to 34.46%, 31.74% and 58.53%, respectively. Furthermore, based on the lap shear test results, by adding 0.3 wt% NH2‐MIL‐101 (Cr) along with 2.5% poly(butyl acrylate‐block‐styrene) to the epoxy adhesive, the lap shear strength of samples increased from 1.05 ± 0.08 MPa to 5.25 ± 0.06 MPa compared to the neat epoxy adhesive. According to the TGA test, the highest thermal stability is related to the sample containing 0.3 wt% of NH2‐MIL‐101 nanoparticles and 2.5 wt% of the copolymer. The image of the fracture surface of the sample containing 0.3 wt%. NH2‐MIL‐101 (Cr) and 2.5 wt% block copolymer shows that the interface of nanoparticles and the matrix improved due to the chemical reaction of functional groups of nanoparticles and adhesive matrix. [ABSTRACT FROM AUTHOR]

In response to the imperative of eco‐friendly material substitution, a comparative cradle‐to‐gate life cycle assessment (LCA) of two epoxy adhesives is presented: a traditional epoxy resin and an innovative self‐curing epoxy derived by epoxidizing poly‐beta‐myrcene (a constituent of Chios Mastic natural resin). Employing ReCiPe 2016 indicators and standard normalization, our study reveals that epoxidized poly‐beta‐myrcene outperforms conventional epoxy in 9 of 18 assessed midpoint indicators, with minimal impact in 7, and marginally higher impact in 2. The superiority of epoxidized poly‐beta‐myrcene extends to all three ReCiPe Endpoint protection areas. Atom economy and the E‐factor are also considered and related to the LCA results. Furthermore, the evaluation demonstrates epoxidized poly‐beta‐myrcene's remarkable environmental favorability compared to a literature bio‐based epoxy across multiple CML‐IA‐baseline indicators. In summary, epoxidized poly‐beta‐myrcene emerges as a promising, ecologically sensitive alternative to current conventional and bio‐based epoxy options. [ABSTRACT FROM AUTHOR]

The effect of different amounts of epoxy functional silane (EFS) as a crosslinking agent in the water-based acrylate adhesives was evaluated for the production of eucalyptus wood panels at different curing temperatures (120°C and 140°C). The thermal stability and dynamic analyses (loss and storage moduli) of the acrylate adhesives with EFS were evaluated. The addition of EFS in the acrylate adhesive increased the thermal degradation, storage, and loss moduli. The thermal degradation, bending test, specific mass, and morphology were evaluated in the wood panels. Significant increases in the storage modulus and bending strength of the wood panels with EFS and acrylate adhesive at 140°C were found. These results demonstrate a potential application of EFS in the production of wood panels aiming towards the manufacture of thicker composites. [ABSTRACT FROM AUTHOR]

Nowadays, FRP composites are widely applied in the construction industry. Their inherent characteristics are used to strengthen structural elements made of various materials and to increase their durability. The following paper contains the results obtained in a conducted research program aimed at determining the ability to improve the durability of epoxy resin modified with the sonication process, microsilica and carbon nanotubes. The adhesive modified was used to adhere a CFRP tape to a concrete surface. Changes in the viscosity, physicochemical parameters and adhesion of the resin were studied. Selected parameters of the concrete substrate prepared using the sandblasting method, determined with the contact profilometry, were also taken into account. During the tests, attention was paid to the thorough execution and preparation of the samples. As a result of the research, it was demonstrated that the adhesion of the modified epoxy adhesive to concrete could be increased by approximately 28% in the case of the addition of carbon nanotubes and by up to 66% in the case of the addition of microsilica. The modifications used, in addition to increasing the adhesion of the resin to the concrete substrate, were also aimed at reducing the weakening of the adhesive joints caused by oxidation of the resin over time. The results obtained will serve as a basis for evaluating the possibility of their use in the practical reinforcement of structural reinforced-concrete elements. [ABSTRACT FROM AUTHOR]

The present study was an attempt to improve the toughness, mechanical and adhesion properties, and thermal stability of a two‐phase epoxy DGEBA/Resole phenolic resin through the use of carboxyl‐modified multi‐walled carbon nanotubes (c‐MWCNTs) and ground rubber tire (GRT) powder. The effect of a hybrid reinforcement containing GRT and c‐MWCNT blend on the mechanical properties, thermal stability, and microstructure of the epoxy‐phenolic adhesive were evaluated by tensile test, TGA, and FESEM, respectively. The formulated adhesive was utilized in a lap joint metal to a composite in order to peruse the adhesion features, where the composite was an epoxy resin reinforced with carbon fibers and the metal was stainless steel 316 L. According to the tensile test, there were 32% rise in tensile strength, 27% rise in modulus, and a 64% rise in toughness with adding 0.5% wt c‐MWCNTs and 15 phr waste GRT powder to the epoxy‐phenolic matrix. Furthermore, adding 1% wt c‐MWCNTs of nanoparticles and GRT powder has resulted in a 15% increase in lap shear strength. It also can be seen that thermal stability for the formulated samples has experienced an upward trend compared to the neat epoxy composite. Highlights: Epoxy adhesives based on GRT Powder, c‐MWCNTs particles and phenolic resin have been successfully prepared.The hybrid uses of GRT Powder and c‐MWCNTs particles can synergistically increase the tensile and lap shear strengthThe addition of c‐MWCNT nano particles and GRT Powder in an epoxy adhesive can have a dramatic rise in the toughness system compared to the neat epoxy adhesive.Maximum degradation temperature of the produced newly adhesive has increased considerably in contrast with the neat epoxy adhesive. [ABSTRACT FROM AUTHOR]

The aim of this research was a comparative analysis of selected mechanical properties of epoxy compounds that were modified with metallic fillers and aged in aqueous environments. The tested epoxy compounds consisted of three components: styrene modified epoxy resin based on Bisphenol A, triethylenetetramine curing agent (resin/curing agent ratio of 100:10) and two types of metallic fillers in the form of particles: aluminum alloy (EN AW-2024–AlCu4Mg1) and tin-phosphor bronze (CuSn10P). Samples were subjected to ageing in 4 water environments: low-, medium- and high-mineralized natural water and in a sugar-containing solution for 1, 2 and 3 months. The epoxy samples were subjected to compressive strength tests in accordance with the ISO 604:2002 standard. It was observed that, among others, the compositions seasoned in low-mineralized water usually achieved the highest average compressive strength. As for filler type, using the bronze filler (CuSn10P) usually achieved the highest average compressive strength results. [ABSTRACT FROM AUTHOR]

Adhesive bonding is an excellent candidate for realising connections for secondary structures in structural applications such as offshore wind turbines and installations, avoiding the risk and associated welding problems. The strength of the adhesive layer is an important parameter to consider in the design process it being lower than the strength capacity of the bonding material. The presence of defects in the adhesive materials undoubtedly influences the mechanical behaviour of bonded composite structures. More specifically, the reduction in strength is more pronounced as the presence of defects (voids) increases. For this reason, a correct evaluation of the presence of defects, which can be translated into damage parameters, has become essential in predicting the actual behaviour of the bonded joints under different external loading conditions. In this paper, an extensive experimental programme has been carried out on adhesively bonded connections subjected to Mode I and Mode II loading conditions in order to characterise the mechanical properties of a commercial epoxy resin and to define the damage parameters. The initial damage parameters of the adhesive layer have been identified according to the Kachanov–Sevostianov material definition, which is able to take into account the presence of diffuse initial cracking. [ABSTRACT FROM AUTHOR]