Cured thermosetting epoxy resin can be dissolved when it is immersed in the solvent N, N dimethylformamide brought to a high temperature (90 ° c to 100 ° c) for several hours. I would like to know what it the chimical process that permet the solvent to dissolve the resin.
DMF is one of the high temperature solvent and can heat it safely to the temperature of your experiment. It is also a good solvent to swell materials like epoxy resin, especially at elevated temperatures. However, it is possible that the tertiary nitrogen group of the solvent is additionally acting as the catalyst for a mild alcoholysis/transesterification for bond rearrangement. Although you did not add alcohol in your solvent, there can be secondary alcohol in your cross linked epoxy especially if the epoxy was not polymerized at high temperature. Those secondary alcohol might act as the partner for this degradation at the temperature you used. For a more detailed mechanism, see the following paper.
https://pubs.rsc.org/en/content/articlepdf/2018/ra/c7ra12787a
DOI: 10.1039/c7ra12787a
Dear all, search for solvolysis and self-healing of epoxy you get complete understanding of bond breaking/reformation of thermosets. In the attached file and starting from page 26 you find major chemical reactions involved in these processes. My Regards
Following another interesting document. My Regards
10.3390/polym11020293
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