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Fourier transform infrared spectroscopy (FT-IR) spectra on the comparison of the two-component adhesives DP270, DP460 and DP125 a. Epoxy b. Hardener.
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In recent years, findings in nanoscience and nanotechnology have deeply influenced many disciplines including the material and mechanical sciences. Polymers including nanostructures have attracted attention as their adoptions in general engineering composites have yielded efficient results. In this study, three different two-component (epoxy-harden...
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Context 1
... spectra on the comparison of the epoxy and the hardener part of the two-component adhesives DP270, DP460, and DP125 are given in Figure 9a and b. ...
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... the spectra in Figure 9a, it can be understood that three different epoxies had polymer matrices somewhat similar to that of bisphenol a and epichlorohydrin reaction. Specific peaks appeared in the fingerprint region, reflecting the partial differences of the resins. ...
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... the peak at ~1730 cm −1 is the C=O peak that appeared due to due the possible differ- ences in the molecular structure according to those of the other adhesives of the epoxy resin. As seen in Figure 9b, characteristic peaks in the spectra of three different adhesive hardeners indicate that these hardeners are typical diamine matter. Therefore, the peaks observed especially between 2300 and 2100 cm −1 can be considered as peaks from hardener material. ...
Citations
... From the analysis, the lap joint shear strength increased with the addition of 1 wt% of CNT, 0.5 wt% of GNP, and 0.5 wt% of CNH to 53%, 49%, and 46%, respectively. 93,[133][134][135] Panta et al. 136 have reviewed the effects of nanofillers such as carbon nanotubes (CNTs), graphene nanoplatelets (GNPs), nano-clay, nano-silica (nano-SiO2), and nano-alumina (nano-Al 2 O 3 ) in new developments of epoxybased adhesives for adhesively bonded applications. The 50% of lap shear strength attained by adding 1 wt% of CNT/ GNP also has good adhesive properties. ...
... The pure epoxy strength was doubled due to adding nano-Al 2 O 3 not to exceed 4 wt%. 93,[133][134][135] Mohammad et al. 137 have conducted an experimental and numerical analysis of adhesive-bonded composite joints from the adhesive of Araldite 2011 and 0.5 wt% reduced graphene oxide (RGO), which is fabricated by a fast and fully scalable method. From this analysis, 0.5 wt% RGObased epoxy adhesives have a good tensile and compressive strength of the composite joints. ...
Among the myriad joining techniques, the adhesive bonding technique is widely used to join complex large-scale composite
structures because of its numerous advantages compared to traditional joining techniques. This article profusely analysed
the various techniques for ameliorating the performance of composite joints, such as bonding methods (secondary bonding,
co-bonding, co-curing, and multi-material bonding), surface modification techniques (plasma, laser surface treatment,
surface grinding, etc.), additional reinforcement techniques (Z pin, wire mesh, nanofiller, etc), and different joint geometries
(stepped joints, half-stepped joints, balanced joints, and scarf joints). Also, the effect of various adhesives and fabrication
techniques on the static and dynamic performance of CFRP and GFRP-based joints was studied in detail. Moreover, this
review addresses the finite element modelling and optimisation techniques on adhesively bonded joints. It has been
observed that the bonding methods, surface modification to enhance the roughness of the adherend, addition of nanofillers,
and variations in joint geometry greatly influence the shear strength, fracture toughness, fatigue, and vibration behaviour of
FRP composite joints.
... First of all, force-elongation curves were obtained as a result of the experiments. Then, true stress-true strain (s t -e t ) curves for adhesives were obtained using the formulas given in equation (1) (Figure 6) [10,12]. ...
In the present study, chemically surface-treated nanoparticles and nanofibers were added to the adhesive to improve the performance of the two-component structural adhesive. In the study, DP460 structural adhesive was used as adhesive, functionalized Multi Walled Carbon Nanotubes (MWCNT-COOH) with COOH and carbon fiber (CF) chemically surface treated with HNO3 solution were used as nanostructures. In the experimental study, eight different parameters were investigated as the nanostructure was (i) undoped, (ii) 1 wt% MWCNT-COOH added, (iii) 1wt%. untreated CF added, (iv) 0.5 wt% chemically treated CF added, (v) 1 wt% chemically treated CF added, (vi) 2 wt% chemically treated CF added, (vii) 0.5 wt% MWCNT-COOH and 0.5 wt% chemically treated CF added, and (viii) 1 wt% MWCNT-COOH and 1wt% chemically treated CF added. According to the results of the study, adding nanoparticles to the adhesive increases the performance of the adhesive by about 12%, while adding nanofibers increases the performance of the adhesive by about 18%. In addition, increasing the inertness and wettability of nanofibers by chemical treatment, as well as the use of nanoparticles and fibers together, significantly increases the performance of the adhesive. In addition, the obtained results were supported by fourier transform infrared spectroscopy (FT-IR) analysis and scanning electron microscopic (SEM) analysis.
... However, it is crucial to develop a strong interfacial adhesion to correctly transfer the load from the polymeric matrix to the nano-reinforcement [13]. Carbon-based nanoparticles, such as carbon nanofibers (CNFs), carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are widely used for this purpose [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. These nanoparticles enhance the fatigue life of bonded joints and can be used for damage detection, as they also improve the electrical properties of the resin they are dispersed in [29][30][31][32][33][34][35][36][37][38][39]. ...
... Carbon-based nanoparticles, such as carbon nanofibers (CNFs), carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are widely used for this purpose [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. These nanoparticles enhance the fatigue life of bonded joints and can be used for damage detection, as they also improve the electrical properties of the resin they are dispersed in [29][30][31][32][33][34][35][36][37][38][39]. ...
The demand for ever-lighter structures raises the interest in bonding as a joining method, especially for materials that are difficult to join with traditional welding and bolting techniques. Structural adhesives, however, are susceptible to defects, but can be toughened in several ways: by changing their chemical composition or by adding fillers, even of nanometric size. Nanomaterials have a high surface area and limited structural defects, which can enhance the mechanical properties of adhesives depending on their nature, quantity, size, and interfacial adhesion. This work analyzes the Mode I fracture toughness of joints bonded with METLBOND® 1515-4M epoxy film and XantuLayr electrospun XD 10 polyamide nanofibers. Two joint configurations were studied, which differed according to the position of the nanomat within the adhesive layer: one had the nanofibers at the substrate/adhesive interfaces, and the other had the nanofibers in the center of the adhesive layer. Double cantilever beam joints were manufactured to evaluate the Mode I fracture toughness of the bonding with and without nano-reinforcement. The nanofibers applied at the substrate/adhesive interface improved the Mode-I fracture toughness by 32%, reaching the value of 0.55 N/mm. SEM images confirm the positive contribution of the nanofibers, which appear stretched and pulled out from the matrix. No fracture toughness variation was detected in the joints with the nanofibers placed in the middle of the adhesive layer.
... For these reasons, different joining methods are used to bring together different types of materials. Some of these techniques are adhesively bonding [9,[13][14][15], welding [16,17], mechanically fastening [18,19] and a combination of different types of techniques called hybrid joints [20]. Among these methods, hybrid joints obtained by combining mechanical fastening (e.g., riveted joints and bolted joints) with conventional adhesive joints have become very popular in recent years [20][21][22][23][24][25][26][27][28]. ...
Glass fiber-reinforced composites are commonly employed as structural materials in many fields. In addition, glass fiber-reinforced composites are frequently used with metals, particularly in the automotive and aerospace industry. In this context, the tensile strengths of simple and hybrid single-lap joints having similar (i.e., aluminum/aluminum and composite/composite) and dissimilar (i.e., aluminum/composite) plates were investigated experimentally in this study. At this point, 6061 aluminum alloy and E-glass/epoxy composite plates were used as the adherends and Araldite 2014-1 was used as the adhesive. The composite adherends produced using the vacuum infusion technique consist of E-glass/epoxy laminates with [0°/90°/+45°/−45°]6 stacking sequence. Two different types of joints (i.e., adhesively bonded and bonded/riveted) were employed for similar and dissimilar joints. In addition, both 3-rivet and 4-rivet joints were used in bonded/riveted joints. The results revealed that the strength of the joints could be considerably increased with the addition of rivets to the adhesively bonded joints. In particular, the results showed that the strength value of the bonded/4-riveted joint is 5.7 times higher than the adhesively bonded joints.
... When designing UAV, the strength of epoxy composites plays an important role [ [23], [24], [25], [26], [27]]. For ER reinforced AF is characterized by high strength, it is insufficient compared to metals. ...
Currently, the production and use of military UAVs in the direction of robotic complexes is actively developing. The purpose and use of military UAVs differ from civilian ones, based on two functions: reconnaissance purpose and a carrier of a warhead. The specifics of military UAVs are their invisibility to enemy radars and ensuring stable transmission of information from the command post. For these purposes, first of all, the UAV material must have the properties of radio transparency. For the production of UAV hulls, power elements, high-strength PCM are needed, which include organoplastics, carbon fiber, fiber glass. The choice of materials for parts of components and assemblies of aviation equipment depends on their operating conditions: operating loads, material properties. Organoplastics (OP) fully meets these requirements among polymer composite materials (PCM). OP have high strength properties along with low dielectric losses (radio transparency) compared to other fiber composites. This paper presents an overview of studies of dielectric and strength properties, as well as ways to improve the mechanical properties of organoplastics. The analysis of the work has shown that for radiotransparent organoplasty, the optimal frequency range of permittivity is 1kHz-12 GHz. The ultimate strength of organoplastics varies in the range from 320 MPa to 1 GPa. The possibilities of increasing the strength of aramid fibers and ways of modifying organoplastics epoxy resins are considered.
... [48] Acetone (Merck 100014) was used as a solvent due to ease of removal from the mixture, the low boiling point, the effective dispersion of nanoparticles, and its low negative effect on mechanical performance. [49][50][51] Then, different weight ratios of 1%, 2%, 3%, and 4% of GNPs were added to the adhesive-acetone mixture, respectively, and mixed mechanically for 30 minutes at 10,000 pm with a light homogenizer. A very large amount (more than 90%) of acetone evaporated during mechanical mixing. ...
In this study, the mechanical response and damage characteristics of single lap joints (SLJs) including graphene nano-platelets (GNPs) were investigated under tensile and three-point bending tests. To this end, Aluminum 2024 substrates were bonded by Araldite 2014-2 adhesive reinforced by GNP with various percentages as 1%, 2%, 3%, and 4% by weight. The results demonstrated that GNP added samples exhibiting a higher ability to resist loads showed better performance for both experiments compared to pure samples. The maximum improvements in the 3 wt.% GNP added samples were obtained as 91.2% in the lap shear test and 45.1% in the three-point bending test. The addition of GNP to the adhesive acted as a barrier against growing cracks, causing the formation of special toughening mechanisms such as crack deviation, bridging, and pull out, which either stopped the cracks or deviated them from their path. These mechanisms improved the fracture characterization of samples in failures. However, more amount of GNP higher than 3 wt.% led to sharp decreases due to the non-uniform local stress concentrations as a result of agglomerations. ARTICLE HISTORY
... The graphene doped thin films show good adhesion on substrates and fracture toughness between layers increases. 15,16 It can be said that the only element currently used for p-type GaN production is magnesium (Mg). 17 The expectation by graphene doping is that it is a p-type semiconductor by localization of carbon atoms instead of nitrogen site in the GaN structure but it can be also shown n-type semiconductor property by replacing Ga site. ...
This study aims to ensure p-type gallium nitride (GaN) thin-film production through graphene (Gr) and to observe the effects of the annealing process on physical properties. A Gr doped GaN thin film on a glass substrate was coated using the thermionic vacuum arc method and an annealing process was applied to this sample at separate temperatures of 300 °C and 400 °C. To investigate the produced samples, elemental composition, electronic states, nanostructural, morphological, and electrical characteristics were determined by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, atomic force microscopy, and Hall effect technique. The thickness of the samples was determined as 60 nm by a Filmetrics F20 thin film analyzer. According to grazing incident-angle XRD patterns of samples, GaN peaks were observed to become dominant after the 400 °C annealing process. The results show that the used production method is suitable for p-type GaN thin film.
... This situation clearly shows the positive effect of the addition of nanostructures on the failure load of the joint when the static failure load of the joint was subjected to a 5%, 10% and 15% fatigue load. In a study by Avinc Akpinar et al., [45] the thermal and mechanical properties of the nanocomposite bulk adhesive (DP460 adhesive reinforced with graphene, carbon nanotube-COOH and fullerene nanostructure) were investigated in detail. Considering the data obtained from the study, according to the results obtained from the presented study, it was determined that the bonding properties of nanoreinforcements affected both the static and fatigue load based on the adhesive-reinforcement interface adhesion, and that the nanostructures that were well bonded to the adhesive had better mechanical properties. ...
Today, adhesively bonded joints are frequently used in the space and aviation industries. Joints used in these sectors are generally subject to dynamic loads due to environmental factors. This study experimentally and numerically investigated the static tensile loads of adhesively bonded joints after fully reversed (combination of tensile and compressive) fatigue loading where nanoadhesives – obtained by adding carbon nanostructures into aerospace grade structural adhesive – were used to bond the joints. Single lap joint specimens were produced using a nanocomposite adhesive obtained by adding 1 wt. % graphene, 1 wt. % carbon nanotubes-COOH and 1 wt. % fullerene C60 nanostructures to a DP460 structural adhesive. AA2024-T3 aluminum alloy and carbon fiber-reinforced composites (CFRCs) with a plain weave fabric (0/90°) were used as adherend materials. First, static tensile tests were applied to these joints to obtain their failure loads and then fully reversed sinusoidal fatigue tests were applied under a constant load amplitude, a frequency of 20 Hz and a load ratio of R = −1. Considering the failure loads obtained from the static tensile tests, 10⁶ fully reversed fatigue loading cycles were applied – which was accepted as an infinite life – at 400 N, 800 N and 1200 N load levels.
The static tensile failure loads and energy values absorbed of these joints were obtained and the change in the failure loads and energy values absorbed of the joints subjected to fatigue was investigated. The static failure loads of aluminum joints bonded with nanoadhesive and subjected to fully reversed fatigue loading increased by approximately 5% to 17%, depending on the nanostructure type added to the adhesive. Moreover, it was observed that there was an increase in loading of approximately 3% to 20% for the nanostructure reinforced joints obtained by using CFRCs with [0/90]6 stacking sequence.
... Alumina nanospheres and nanorods integration shows both a significant increase of joint shear strength and mode I fracture toughness ( Gupta et al., 2019 ). Similarly, carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) can be used as nano-reinforcements to improve stiffness, strength, fracture toughness and electrical conductivity of bonded joints ( Takeda and Narita, 2017 ;Burkholder et al., 2011 ;Jakubinek et al., 2015 ;Gude et al., 2015 ;Korayem et al., 2016 ;Khoramishad and Khakzad, 2018 ;Akpinar et al., 2018 ;Zielecki et al., 2017 ;Jojibabu et al., 2019 ;Cha et al., 2019 ). An efficient way to reinforce epoxy resins is the integration of polymeric nanofibers, even composite ones, inside the matrix ( Huang et al., 2003 ). ...
The improvement of the fracture toughness of adhesive joints is a key factor in many structural applications. The ability of nylon electrospun nanofibrous mat to act as an adhesive carrier and reinforcing web in adhesive bonding has been demonstrated by the Authors in previous works. It has been shown that the impregnation method developed and refined during the previous studies allow generating high-quality pre-preg nanomats out of a 2k unfilled epoxy resin. By applying this methodology, in the present work, rubbery nanofibrous mats have been adopted for the first time to reinforce and increase the fracture toughness of adhesive joints. Rubbery nanofibers were produced by electrospinning of nitrile butadiene rubber (NBR) and poly(ε-caprolactone) (PCL). The addition of the semi-crystalline polymer (PCL) is exploited to maintain the nanofibrous morphology, which the rubber alone (NBR) would not be able to ensure due to its low glass transition temperature (Tg). The nanofibers thus obtained have been integrated into a two-component high strength epoxy resin for structural applications. S235 steel adherends for Double Cantilever Beam (DCB) tests have been manufactured and sandblasted to improve adhesion. An optimization of the sandblasting parameters (distance, pressure, angle and time) has been carried out evaluating the shear strength and the fracture surfaces on S235 steel Single Lap Joints (SLJ). Finally, DCB tests have been performed to compare the mode I fracture toughness with and without the rubbery electrospun nanomats.
... Surface pre-treatment of thermoset CFRPs for adhesive bonding is a highly active research area with several recent studies on mechanical and chemical surface treatment techniques such as sanding [5], grit-blasting [6], chemical etching [7], laser [8][9][10][11][12], plasma [13,14], flame [15] and peel-ply based treatments [6,16,17], as well as novel techniques such as the soft-layer method [18,19] and laser-based surface patterning [20,21]. Use of nanocomposite adhesives produced by adding nanostructures like graphene, carbon nanotube, SiO 2 , fullerene, organoclay to the adhesive polymer is reported to improve the mechanical properties of the bulk adhesive and the joint [22][23][24][25][26][27]. References [25][26][27] evaluates the effect of doping different nanostructures in rigid and toughened adhesives and reports that the type of nanostructure and its quantity, adhesive type, and adherend material significantly influence the joint performance and this technique significantly reduces the loss in joint strength due to thermal cycling. ...
Light-weighting of transportation structures necessitates multi-material design employing composites and aluminium, with thermoplastic composites being of increasing interest to the industry. Adhesive bonding is a viable solution for joining dissimilar materials, but joint performance can be considerably affected by surface preparation. In this paper, alumina grit-blasting is investigated as a surface preparation technique for thermoplastic-matrix composites to be bonded to aluminium alloys. Grit-blasting is performed on composite adherends for varying durations, and the resulting chemical and morphological modifications are analysed using goniometry, profilometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Adhesively-bonded single-lap joints are tested at quasi-static and dynamic (0.5 m/s) loading rates, and fractography analysis is performed at macro and micro scales. It is found that high lap shear strength and work-to-failure can be achieved through optimisation of the grit-blasting parameters. The optimised process produces a composite surface with plasticised matrix, minimal fibre exposure, and favourable surface chemistry for adhesive bonding. Grit-blasting can thus be a simple, yet effective surface preparation technique for composites to be bonded to aluminium.
