Multiscale Network Structure Analysis by Time Domain ¹H DQ NMR and DMA of Resorcinol Diglycidyl Ether‐Jeffamine Matrices

Abstract

Epoxy-amine networks have found their way in everyday and technical applications for the past several years. Special attention on biosourced monomers has increased for sustainable development applications. This work investigates the influence of the chemical structure on the thermomechanical behavior of biosourced epoxy-based matrices through a multiscale approach. Resorcinol Diglycidyl Ether (RE) was hardened with Jeffamines (molecular weights M W � 230, 500, 800, and 2000 g mol À 1). Bisphenol A Diglycidyl Ether (DGEBA) was also studied for comparison. By combining Dynamic Mechanical Analysis (DMA) and Time Domain Nuclear Magnetic Resonance (NMR), it was proven that the difference in the chemical structure of Jeffamines yielded matrices with distinct network morphologies, influencing the behavior of the matrices. A linear relationship between the crosslink densities probed by DMA and Time NMR was observed, demonstrating a direct influence of the network structure at the molecular level with the obtained macroscopic properties. It was demonstrated that physical entanglements in these matrices act as mechanical reinforcements. This work shows a novel and robust multiscale experimental approach allowing to understand key structureproperty relationships for epoxy-amine thermosets.

One-Pot Terpolymerization Synthesis of High Carbon Biocontent Recyclable Epoxy Thermosets and Their Composites with Flax Woven Fibers

“…By using a combination of solid state Multiple Quanta 1 H NMR corroborated with DMA analysis Rios de Anda et.al. − demonstrated for highly cross-linked polymers that the truly elastic domain ensuring the same state of molecular mobility occurs at T = T g + 90 °C. Therefore, the cross-link densities calculated in accord with this theory, show the highest values ∼0.97 mmol·cm –3 in the systems with ELO/MA/0.5DPG, illustrating that these networks have the optimal properties in terms of glass transition, storage moduli, and thermal stabilities.…”

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

“…1 H TD-DQ NMR has been proven as a powerful technique to investigate the intrinsic morphology of cross-linked polymers. It has been successfully used to characterize elastomeric-like materials such as natural and synthetic rubbers, poly­(dimethylsiloxane) (PDMS), and other elastomers, as well as the influence of chemical modifications, variation of cross-link density, and chemical and thermal aging on such materials. − Recent works have addressed the characterization of highly constrained poly­(trimethylene carbonate) (PTMC) , and eugenol-based networks, as well as epoxy-amine-based matrices , with this technique. Such investigations successfully yielded a good agreement between the materials’ network structure and their macroscopic static instantaneous mechanical properties.…”