Influence of curing, post-curing and testing temperatures on mechanical properties of a structural adhesive

Jahani, Younes; Baena, Marta; Barris, Cristina; Perera, Ricardo; Torres, Lluís

doi:10.1016/j.conbuildmat.2022.126698

Cited by 50 publications

(31 citation statements)

References 33 publications

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“…The glass transition temperature increases when curing the resin at a temperature below its T g . [ 37 ] Thus, for the present comparison, when the post‐curing temperature was raised to the glass transition temperature values of the polymer, the T g values tend to show significantly less improvement. The resin formulations BBR1.1, BBR1.2, and BBR1.3 (with diluent) also reported a rise in their T g value with the curing temperature.…”

Section: Resultsmentioning

confidence: 75%

“…Curing the resin at a temperature below the upper bound value of the resin ( T g∞ ) can shift the heat flow peak vs. temperature towards the right, as presented in Figure 5. [ 37 ] Based on these findings, further comparison between the two systems is carried out through DMA analysis. The two curing cycles presented in Table 4 were investigated, targeting the maximum T g values by focusing on the full crosslink density of the epoxy system as an outcome of the thermal curing.…”

Section: Resultsmentioning

confidence: 99%

“…Quite the reverse, thermal degradation can reduce mechanical properties when the post‐curing temperature is raised above the T g∞ . [ 37 ] The curing temperature selected for the biobased and recyclable resin BBR2.2 is below the T g∞ value of the resin. Thus, the mechanical properties attained an improvement.…”

Section: Resultsmentioning

confidence: 99%

“…The post‐curing can activate the crosslinking faster and improve the composite's mechanical properties. [ 37 ]…”

Section: Resultsmentioning

confidence: 99%

“…The flexural modulus and percentage elongation did not achieve a notable improvement. A research study by Jahani et al [ 37 ] also reported that the elastic modulus tends to have a constant value upon post‐curing at temperatures below the resin's upper bound value ( T g∞ ).…”

Section: Resultsmentioning

confidence: 99%

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Characterization of biobased epoxy resins to manufacture eco‐composites showing recycling properties

et al. 2022

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The present study details the composite fabrication, characterization, and full recyclability of the biobased polymer resins with flax fiber as the reinforcement. Two different biobased resins are selected by varying the resin hardener combination and curing parameters for the comparison. The optimum parameters for the composite preparation are finalized by evaluating the neat resin's mechanical and glass transition temperature (Tg) values. According to the results obtained, a biobased epoxy resin cured by a cleavable hardener displayed the highest Tg (i.e., 93.5°C) upon a two‐step cure cycle, guaranteeing full recyclability. Subsequently, eco‐composite flat panels are manufactured using the selected formulation reinforced with commercial flax‐based fabric. These panel's flexural strength, modulus, and interlaminar shear strength are measured after each curing step. The recyclability yield of the composite is tested, through a specific chemical process, demonstrating the possibility of separating and recovering both the constituent fibers and resin from the composite panels.

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Section: Resultsmentioning

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…The post‐curing can activate the crosslinking faster and improve the composite's mechanical properties. [ 37 ]…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Characterization of biobased epoxy resins to manufacture eco‐composites showing recycling properties

et al. 2022

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Accelerated‐curing epoxy structural film adhesive for bonding lightweight honeycomb sandwich structures

Zhao

Qiao

et al. 2022

J of Applied Polymer Sci

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Accelerating the curing of epoxy/aromatic amine adhesives and improving their toughness are challenges in heat-resistant epoxy structural adhesives. Herein, we report an epoxy/aromatic amine adhesive accelerated curing system with an oxo-centered trinuclear (chromium III) complex, which is toughened using a thermoplastic block copolymer (TPBC). The reaction characteristics, heat resistance, microstructure, and bonding properties of the accelerated epoxy adhesives were analyzed. The reaction peak temperature of the epoxy with 3% catalyst was 113.1 C, which was 113.6 C lower than that of epoxy without catalyst, and the modified epoxy resin demonstrated a potential for rapid curing at medium temperature. The glass transition temperature of the TPBC-toughened epoxy adhesive was 125 C after curing, indicating excellent thermal stability after medium temperature curing. The introduction of the TPBC increased the single-lap shear strength of the epoxy adhesive without reducing its heat resistance. The shear strength at room temperature and 120 C of the modified epoxy adhesive with 50 phr of TPBC was 25.2 and 10.9 MPa, respectively. Moreover, the epoxy film adhesive exhibited outstanding bonding properties when used in the bonding of lightweight honeycomb sandwich structures.

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Improving interfacial adhesive bond durability of a structural epoxy with steel using a tannic acid‐based additive for underwater applications

Babu,

Zhang,

Massou

et al. 2023

J of Applied Polymer Sci

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This study explores the applicability of a tannic acid‐based (TA‐AGE) additive to improve interfacial bond durability of a structural epoxy (Ep.) adhesive for underwater applications. A modified epoxy M(Ep.) was prepared from Ep. by incorporating 1 wt% (optimized) TA‐AGE additive. Although the cohesive properties of Ep. were slightly affected by the modification, underwater adhesion was improved. Incorporation of TA‐AGE additive in the adhesive can strengthen the interfacial bonds by forming more noncovalent interactions with the adherend surface. In addition, a 6‐month durability study in distilled water at 20°C, 40°C, and 60°C was performed to study the effect of water uptake on the evolution of viscoelastic, tensile properties and interfacial bond durability of Ep. and M(Ep.). With aging, the tensile properties of M(Ep.) degraded more rapidly than Ep. due to higher water uptake. Steel joints bonded with M(Ep.) in air, but cured underwater, had strength retention of 97%, 99% and 107% in 20°C, 40°C, and 60°C water, respectively, after 6‐month aging. Meanwhile, joints prepared underwater with M(Ep.) had a strength retention of 77% in 20°C water. Joint strength retention (%) in both cases was significantly higher than Ep. bonded joints aged under similar conditions.

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Influence of curing, post-curing and testing temperatures on mechanical properties of a structural adhesive

Cited by 50 publications

References 33 publications

Characterization of biobased epoxy resins to manufacture eco‐composites showing recycling properties

Characterization of biobased epoxy resins to manufacture eco‐composites showing recycling properties

Accelerated‐curing epoxy structural film adhesive for bonding lightweight honeycomb sandwich structures

Improving interfacial adhesive bond durability of a structural epoxy with steel using a tannic acid‐based additive for underwater applications

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