Multiscale Characterization of Creep and Fatigue Crack Propagation Resistance of Fully Bio-Based Epoxy-Amine Resins

• Published in: ACS applied polymer materials Vol. 3; no. 10; pp. 5134 - 5144
• Main Authors: Mattar, Nour, Hübner, Fabian, Demleitner, Martin, Brückner, Alexander, Langlois, Valérie, Renard, Estelle, Ruckdäschel, Holger, Rios de Anda, Agustín
• Format: Journal Article
• Language: English
• Published: American Chemical Society 08.10.2021
• Subjects: bio-based thermosets; creep; fatigue crack propagation; lifetime resistance; mechanical aging
• ISSN: 2637-6105; 2637-6105
• DOI: 10.1021/acsapm.1c00894

In this study, accelerated creep and dynamic fatigue crack propagation (FCP) measurements were carried out on fully bio-based epoxy-amine thermoset resins. Formulations based on resorcinol diglycidyl ether (RE) were cured with an aliphatic (hexamethylenediamineHMDA), a cycloaliphatic (diamine-limoneneDA-LIM), or an aromatic (diamine-allyl eugenolDA-AE) structure. Diglycidyl ether of bisphenol A (DGEBA) cured with HMDA served as a petrosourced benchmark. By considering a multiscale experimental approach combining these experiments with time-domain NMR, it was found that for DGEBA/HMDA, RE/DA-LIM, and RE/DA-AE, their aging properties depend on the resin network structure characterized by the chemical and physical cross-link density. It was demonstrated that the three considered fully bio-based matrices showed better aging resistance compared to DGEBA/HMDA. For RE/HMDA, which possesses a lower experimental cross-link density than expected, physical entanglements probed by NMR act as semihard cross-links conferring a more ductile behavior. This leads to RE/HMDA showing comparable aging properties to those of RE/DA-LIM and RE/DA-AE. This work shows that the studied fully bio-based epoxy-amine resins possess remarkable fatigue crack resistance properties and can be considered as potential candidates for functional applications. Finally, the proposed multiscale approach combining macroscopic mechanical studies with molecular time-domain NMR allowed us to soundly deepen the understanding of the structure–property relationship for such functional materials.