Examining the early stages of thermal oxidative degradation in epoxy-amine resins

Morsch, Suzanne; Liu, Y.; Lyon, S.B.; Gibbon, Simon; Gabriele, Benjamin P. A.; Malanin, Mikhail; Eichhorn, Klaus‐Jochen

doi:10.1016/j.polymdegradstab.2020.109147

Cited by 40 publications

(23 citation statements)

References 55 publications

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“…The horizontal axis represents the wavenumber, and the vertical axis represents the absorbance. The peak at 1,733 cm −1 corresponds to the peak of the carbonyl group, [39,40] which is similar to the peak at 1,738 cm −1 , as discussed in a previous study. [21] On magnification, this peak rises broadly in the range of 1,730-1,750 cm −1 .…”

Section: Estimation Of the Cause Of Degradation From The Extracted Wavenumberssupporting

confidence: 86%

Estimating the mechanical residual strength from IR spectra using machine learning for degraded adhesives

Shimamoto

Akiyama

2021

The Journal of Adhesion

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To improve the long-term reliability of adhesively bonded joints, it is important to evaluate the degradation of adhesives on exposure to high-temperature and high-humidity environments. Further, it is important to evaluate the change in material properties, such as mechanical residual strength. Although Fourier transform infrared (FTIR) spectroscopy is widely used to investigate the chemical structures in materials, it is difficult to identify the cause of degradation due to the complex composition of adhesives. This study aimed to develop a simple method for extracting the features related to degradation using FTIR spectroscopy, and to estimate the mechanical residual strength. The surface of the adhesives after immersion exposure to water at a high temperature was analysed using FTIR spectroscopy, and their mechanical strength was measured. The correspondence between them was demonstrated using machine learning. Several linear regression methods were used and compared; the model based on Lasso regression was determined to be the most suitable for extracting features and estimating residual strength. Furthermore, it was indicated that the developed model could be used to identify areas where there is a loss of strength.

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Section: Estimation Of the Cause Of Degradation From The Extracted Wavenumberssupporting

confidence: 86%

Estimating the mechanical residual strength from IR spectra using machine learning for degraded adhesives

Shimamoto

Akiyama

2021

The Journal of Adhesion

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“…A recent report by Morsch and co‐workers discussed the thermal oxidative degradation of an epoxy‐amine resin, where peaks at 1738 and 1658 cm −1 emerged over time during thermal ageing at 60 °C, and exhibited a linear trend. [ 55 ]…”

Section: Resultsmentioning

confidence: 99%

Fluorine‐Free Superhydrophobic Coatings: Rapid Fabrication and Highly Efficient Oil/Water Separation

Silva

Lucas

Advíncula

2020

Macro Materials & Eng

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In this work, a rapid method is demonstrated to obtain a fluorine‐free superhydrophobic/superoleophilic coating by a simple two‐step method: dip‐coating and oven curing. The chemical structure of the coating is based on the crosslinking reaction of an alkyl methacrylate, a dimethacrylate (crosslinker) and a silane (adhesive), using AIBN as initiator, toluene as solvent, and silica nanoparticles to enhance surface roughness. Chemorheology results show that the coating is fully cured even in 20 min at 100 °C, exhibiting a water contact angle (CA) of 162 ± 2°, sliding angle (SA) of 4 ± 1°, nanometrical structures throughout the surface, and excellent adhesion properties for the mesh screen. The coating exhibits outstanding oil/water separation efficiency (96–99%) for seven different types of oil (gasoline, diesel, petroleum ether, hexane, toluene, chloroform, and dichloromethane), and in addition presents high recyclability. Based on nonisothermal TGA, the activation energy of degradation, calculated using the Kissinger and Ozawa models, is 113.5 and 114 kJ mol‐1, respectively. Finally, the coating is thermally aged at 150 °C: the CA exhibits a smooth decrease up to 129 ± 1° at 120 min, and FTIR analysis shows structural changes possibly related to the generation of thermal oxidation products.

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“…[34][35][36][37][38][39][40] Band assignments vary in the literature, but broadly, the 1731 cm À1 band corresponds to carbonyl groups, whereas absorbance around 1660 cm À1 is associated with alkene, imine, azadiene, oxime, or amide functional groups. 34,36,37,[41][42][43][44][45][46] In the case of TGGDM cross-linked with diaminodiphenyl sulfone, dehydration and the formation of propenal has also been reported to occur at temperatures >125 C. 33 Since all these functional groups are all highly polar, oxidation is expected to influence water sorption behavior. Thus, in order to minimize the contribution of oxidized material to water uptake experiments, specimens cured for 5 min at 200 C, 15 min at 150 C, and 60 min at 100 C for were selected for analysis.…”

Section: In-situ Fourier Transform Infrared Spectroscopymentioning

confidence: 99%

“…In-situ FTIR analysis did, however, demonstrate that rapid oxidation is activated at 200 C, and not at 150 C. Whilst the data indicates that the extent of oxidation for resins cured for 5 min at 200 C is minimal, the oxidation of highly cross-linked resins is known to proceed via diffusion limited mechanisms, initiating at the polymer-air interface and progressing into the bulk of the material. 36,39,45,46,51,52 Since oxidation of the resin is clearly rapid at 200 C, some degree of surface oxidation is expected to be present before it is detectable by infrared analysis. We therefore attribute enhanced water sorption into the resins cured at 200 C to the introduction of polar functional groups at the surface of these coatings by oxidation.…”

Section: Dynamic Vapor Sorptionmentioning

confidence: 99%

Internal topology and water transport in tetrafunctional epoxy resins

Morsch

Lyon

Gibbon

et al. 2022

J of Applied Polymer Sci

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Water sorption into epoxy resins limits the performance lifetime of many composites, adhesives, and coatings. One hypothesis for the well‐known hygroscopicity of epoxies is that the well‐known internal nodular topology of epoxy networks enhances permeability. This theory has however remained untested to date, since previous attempts to manipulate the internal topology have been accompanied by changes in the hydrogen bonding capability of resins, which dominates water uptake. Here, the nanostructure of highly cross‐linked network polymers based on tetra glycidyl diaminodiphenyl methane is varied in the absence of significant polarity effects by careful optimization of the cure schedule. The internal morphology of resins cured at 100, 150, and 200°C are characterized using Peakforce tapping mode atomic force microscopy, whilst the cure progression at each temperature is analyzed using in‐situ transmission mode infrared spectroscopy. Distinct nodular morphologies are found to form at high cure temperatures (150 and 200°C), where spectroscopic analysis demonstrates that excess epoxy consumption occurs prior to the gel point, as a result of intra‐cluster cross‐linking and reduced reaction selectivity. Surprisingly, the establishment of an internal nanostructure is, however, found to have negligible effect on the extent and kinetics of moisture sorption.

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Examining the early stages of thermal oxidative degradation in epoxy-amine resins

Cited by 40 publications

References 55 publications

Estimating the mechanical residual strength from IR spectra using machine learning for degraded adhesives

Estimating the mechanical residual strength from IR spectra using machine learning for degraded adhesives

Fluorine‐Free Superhydrophobic Coatings: Rapid Fabrication and Highly Efficient Oil/Water Separation

Internal topology and water transport in tetrafunctional epoxy resins

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