Abstract:High‐performance room temperature‐cure epoxy structural adhesives utilizing simplified formulation are developed. The developed structural adhesive consists of diglycidyl ether of bisphenol A (DGEBA) and novolac epoxy blend as a base resin, micrometer‐sized silica particles as a reinforcing filler, and triethylenetetramine as a curing agent. The developed ambient temperature‐cure epoxy structural adhesive with optimized formulation exhibits outstanding properties including high glass transition temperature of … Show more
“…This could be attributed to proper interaction and hydrogen bonding between the hydroxyl groups on the phenolic resin and the carbonyl groups on the BCP, and also with the substrate, which led to improved adhesion. [ 34 ] In this case, the resultant shear strength was larger than that of either epoxy/30‐phr phenolic resin or epoxy/3.75‐phr BCP, indicating the synergetic effect of the two when applied together at the indicated dosages. The presence of the phenolic resin and BCP facilitated the ring‐opening of the epoxy group, thereby increasing the cross‐linking and hence adhesion to the substrate, that is, shear strength.…”
In this research, phenolic resin and poly (butyl‐acrylate‐block‐styrene) copolymer were used in the formulation of epoxy adhesive to improve its thermal stability and toughness. Also, in order to improve the mechanical properties such as the modulus and tensile strength, aluminum oxide nanoparticles (NPs) were added to the epoxy based resin. Effects of different factors such as percent contents of phenolic resin, toughening agent, and aluminum oxide NPs on the microstructure, mechanical properties, and thermal stability of the epoxy‐based adhesives were investigated. Thermogravimetric analysis, Fourier transform infrared spectroscopy, and field‐emission scanning electron microscopy were used to investigate the thermal, mechanical, and morphological properties of the prepared epoxy adhesive samples. In addition, the curing kinetics of the optimal specimens was studied based on differential scanning calorimetry (DSC). The experimental results indicated that the phenolic decreased strength of dog‐bone samples, while increased the adhesion strength in metal‐to‐metal single‐lap strength. On the other hand, addition of block‐copolymers as toughening agent led to a consistent decrease in the modulus as well as increasing the tensile strength. Also, results of single‐lap strength tests showed that, in the optimal quad system, the four components exhibit synergetic effects and show a single‐lap strength that is 152% higher than that of pure epoxy. The DSC analysis indicated that the presence of alumina NPs and block‐copolymers tend to reduce the initial curing temperature while increasing the curing reaction heat.
“…This could be attributed to proper interaction and hydrogen bonding between the hydroxyl groups on the phenolic resin and the carbonyl groups on the BCP, and also with the substrate, which led to improved adhesion. [ 34 ] In this case, the resultant shear strength was larger than that of either epoxy/30‐phr phenolic resin or epoxy/3.75‐phr BCP, indicating the synergetic effect of the two when applied together at the indicated dosages. The presence of the phenolic resin and BCP facilitated the ring‐opening of the epoxy group, thereby increasing the cross‐linking and hence adhesion to the substrate, that is, shear strength.…”
In this research, phenolic resin and poly (butyl‐acrylate‐block‐styrene) copolymer were used in the formulation of epoxy adhesive to improve its thermal stability and toughness. Also, in order to improve the mechanical properties such as the modulus and tensile strength, aluminum oxide nanoparticles (NPs) were added to the epoxy based resin. Effects of different factors such as percent contents of phenolic resin, toughening agent, and aluminum oxide NPs on the microstructure, mechanical properties, and thermal stability of the epoxy‐based adhesives were investigated. Thermogravimetric analysis, Fourier transform infrared spectroscopy, and field‐emission scanning electron microscopy were used to investigate the thermal, mechanical, and morphological properties of the prepared epoxy adhesive samples. In addition, the curing kinetics of the optimal specimens was studied based on differential scanning calorimetry (DSC). The experimental results indicated that the phenolic decreased strength of dog‐bone samples, while increased the adhesion strength in metal‐to‐metal single‐lap strength. On the other hand, addition of block‐copolymers as toughening agent led to a consistent decrease in the modulus as well as increasing the tensile strength. Also, results of single‐lap strength tests showed that, in the optimal quad system, the four components exhibit synergetic effects and show a single‐lap strength that is 152% higher than that of pure epoxy. The DSC analysis indicated that the presence of alumina NPs and block‐copolymers tend to reduce the initial curing temperature while increasing the curing reaction heat.
“…Therefore, the lap shear strength phenomenon of adhesive joints mainly depends on the dispersion of nanofiller, wettability, and faying surface characteristics that provide better interlocking with the adhesive. 43 The value of lap shear strength of EP adhesive, MWCNT-EP adhesive, and MNCs are mentioned in Table 4.Figure 19.Lap shear strength versus strain (%) curves of neat EP, MWCNT-EP, and MNCs adhesive joint.Figure 20.Area under lap shear strength versus composition (wt.%) plot of neat EP, MWCNT-EP, and MNCs.…”
Section: Resultsmentioning
confidence: 99%
“…Therefore, the lap shear strength phenomenon of adhesive joints mainly depends on the dispersion of nanofiller, wettability, and faying surface characteristics that provide better interlocking with the adhesive. 43 The value of lap shear strength of EP adhesive, MWCNT-EP adhesive, and MNCs are mentioned in Table 4.…”
Exploiting the boundless potential of multi-walled carbon nanotubes (MWCNTs) is the critical issue in developing multifunctional nanocomposites. In this study, the MWCNTs are exfoliated by ZrO2 nanoparticles using the ultrasonication technique. The obtained MWCNT/ZrO2 hybrid nanofiller is infused in the epoxy matrix to produce multifunctional nanocomposites with superior thermo-mechanical and anti-corrosive properties. The physical, morphological, and structural properties of MWCNT/ZrO2 hybrid nanofiller are successfully studied by using XRD crystallography, Raman spectroscopy, and transmission electron microscopy analysis. The chemical interaction between the MWCNT/ZrO2 hybrid nanofiller with the epoxy (EP) matrix is evaluated using FTIR spectroscopy. Results indicated that the corrosion protection performance of mild steel coated with MWCNT/ZrO2 hybrid epoxy nanocomposite (MNC) is considerably increased at 1.0 wt.% of MWCNT/ZrO2 hybrid nanofiller by reducing the corrosion rate from 8.82 MPY to 56 × 10−3 MPY. Furthermore, the tensile strength and lap shear strength of MNC with the same loading content is improved by 67.8% and 58.04%, respectively, compared to neat EP. The field emission scanning electron microscopy images of tensile fracture surfaces of MNC (1.0 wt.%) confirm the cluster-free uniform dispersion of MWCNTs in the EP matrix.
“…As the temperature decreases, the adhesive fracture occurs earlier, i.e. before the adhesive undergoes massive deformation, which reduces the strength and toughness [46,50].…”
Section: Analysis Of the Dumbbell-shaped Samples At -60 And 120℃mentioning
Highlights:1-A new approach was developed for designing epoxy based adhesives with high mechanical, adhesion and thermal properties by adding butyl acrylate block styrene copolymer, phenolic resin, and zirconia nanoparticles. 2-The hybrid of butyl acrylate block styrene copolymer, phenolic resin, and zirconia nanoparticles showed synergistic effects on the aluminium -aluminium single lap joint, butt joint tensile strength, and T-peel strength. 3-Temperature enhancement and decrement declined the adhesion strength of the aluminium -aluminium single lap joint strength and butt joint tensile strength. 4-Proposed toughening mechanisms for finding structure-property association in epoxy adhesives.
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