Thermal-oxidation of epoxy/amine followed by glass transition temperature changes

Esteve Ernault (1) , Emmanuel Richaud (1) , Bruno Fayolle (1)

1 PIMM - Laboratoire Procédés et Ingénierie en Mécanique et Matériaux

Thermal oxidation of three epoxy resins differing by the nature of prepolymer (bisphenol A diglycidyl ether and 1,4-butanediol diglycidyl ether) and hardener (isophorone diamine and 4,7,10-Trioxa-1,13-tridecanediamine) was studied by monitoring changes in glass transition temperature using DSC. Results were discussed using the DiMarzio's approach in which parameters are estimated from an additive group contribution. This theory allowed a fair assessment of Tg values for unaged networks. During oxidation, epoxy networks were shown to undergo chain scissions occurring in great part in hydroxypropyl ether and isophorone groups. However, the exploitation of Tg changes showed the coexistence and even the predominance of crosslinking in materials having linear aliphatic segments. The DiMarzio's approach was used to discuss the possibility of intramolecular cyclization or intermolecular crosslinks which were shown to predominate. Crosslinks were tentatively justified from a mechanistic point of view and quantified depending on experimental conditions.

Mots clés: Epoxy/diamine; Glass transition; Chain scission; Crosslinking

Domaines: Polymères; Matériaux; Mécanique [physics.med-ph]

Esteve Ernault, Emmanuel Richaud, Bruno Fayolle. Thermal-oxidation of epoxy/amine followed by glass transition temperature changes. Polymer Degradation and Stability, 2017, 138, pp.82-90. ⟨10.1016/j.polymdegradstab.2017.02.013⟩. ⟨hal-01493877⟩