Epoxy Cure Observed by Ultrasound, NMR and WAXS

Challis, R.E.; Freemantle, R. J.; Fuller, W.; Martin, C.; Mahendrasingham, A.; Chadwick, D. L.; Cocker, R.P.

doi:10.1007/978-1-4615-4791-4_280

Cited by 1 publication

(3 citation statements)

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“…Distances associated with C–C are the average carbon–carbon distances in the material. Finally, a new structure (H–H) has been attributed previously to either the ordering of the bisphenol epoxy monomers or the ordering of hardeners from curing. , …”

Section: Resultsmentioning

confidence: 95%

“…Finally, a new structure (H−H) has been attributed previously to either the ordering of the bisphenol epoxy monomers or the ordering of hardeners from curing. 22,23 Curing was performed online during WAXS acquisition to validate that H−H was a result of the curing process and not from some other structural feature in the prepolymer formation. At room temperature before significant curing occurred, the uncured BPA-H formulation resembled the pure BPA resin (see Figure 3).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…X-ray diffraction-based techniques are powerful tools for the direct elucidation of material structures. Wide-angle X-ray scattering (WAXS), in particular, is used routinely for investigating polymers. − A number of studies have used WAXS for investigating the structural transformation of liquid crystal polymers integrated in polymer thermosets. − However, limited work uses WAXS to study the structural transitions of the epoxy polymer networks, which are generally considered amorphous. − Even though WAXS is most powerful when studying crystalline materials, structural information is also contained in the WAXS pattern of amorphousand even liquidmaterials . Understanding the WAXS pattern and the corresponding structural features of the amorphous epoxy thermoset could illuminate subtle changes in the polymer network from thermal perturbations, which may affect the material performance.…”

Section: Introductionmentioning

confidence: 99%

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Thermally Induced Structural Transitions in Epoxy Thermoset Polymer Networks and Their Spectroscopic Responses

Dwyer

Isbill

Brubaker

et al. 2023

ACS Appl. Polym. Mater.

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The polymer network structure of epoxy thermosets plays a significant role in its final material properties. However, the effects of mild thermal exposure on these network structures are poorly studied. In this work, wide-angle X-ray scattering was used to investigate the polymer network structure of two epoxy thermosets: homopolymerized bisphenol A (BPA) epoxy resin and BPA epoxy resin cured with a polyether amine hardener (BPA/T-403). Using density functional theory and wide-angle X-ray scattering, insights into the polymer network structure were obtained. Diffraction features were determined to originate from hardener-to-hardener molecular distance, perpendicular π–π stacking of aromatic p-phenylene rings, and the average carbon–carbon distance in the polymer. Thermal exposure was found to permanently alter these structural features for both thermosets, with an increase in the π–π stacking distance. Homopolymerized BPA had an additional decrease in the hardener-to-hardener distance. These structural alterations were found to be detectable using Fourier transform infrared spectroscopy and Raman spectroscopy, with changes in the hardener-to-hardener distance having the largest variations in the resulting spectra specifically at the aromatic and ether frequencies.

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Section: Resultsmentioning

confidence: 95%

Section: ■ Results and Discussionmentioning

confidence: 99%