Curing of epoxy systems at sub-glass transition temperature

• Published in: Journal of applied polymer science 2006-03, Vol.99 (6), p.3669-3676
• Main Authors: Kroutilová, Irena, Matějka, Libor, Sikora, Antonín, Souček, Kamil, Staš, Lubomír
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical properties; chemorheology; epoxy network; Exact sciences and technology; gelation; glass transition temperature; Polymer industry, paints, wood; Properties and testing; Technology of polymers; vitrification
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.22548

Three epoxy‐amine thermoset systems were cured at a low ambient temperature. Evolution of the reaction kinetics and molecular structure during cure at the sub‐glass transition temperature was followed by DSC and chemorheology experiments. The effect of vitrification and the reaction exotherm on curing and final mechanical properties of the epoxy thermosets was determined. Thermomechanical properties of the low‐temperature cured systems depend on the reaction kinetics and volume of the reaction mixture. Curing of the fast‐reacting system in a large volume (12‐mm thick layer) resulted in the material with Tg exceeding the cure temperature by 70–80°C because of an exothermal temperature rise. However, the reaction in a too large volume (50‐mm layer) led to thermal degradation of the network. In contrast, thin layers (1.5 mm) were severely undercured. Well‐cured epoxy thermosets could be prepared at sub‐Tg temperatures by optimizing reaction conditions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3669–3676, 2006