A low resolution pulsed NMR and ultrasound study to monitor the cure of an epoxy resin adhesive

Autor: D.J. Dare, R.P. Cocker, R.E. Challis, D.L. Chadwick
Rok vydání: 1998
Předmět:
Zdroj: International Journal of Adhesion and Adhesives. 18:319-331
ISSN: 0143-7496
DOI: 10.1016/s0143-7496(98)00013-x
Popis: The cure of an epichlorohydrin-bisphenol A resin and hardener containing a primary diamine and an amido-polyamine has been studied using two complementary non-invasive techniques. Low resolution pulsed nuclear magnetic resonance has been used to track the change from viscous liquid to crosslinked solid as the resin cured by following the free induction decay of magnetically active hydrogen nuclei. The Carr–Purcell–Meiboom–Gill technique resolved two changing components in the liquid phase. It is suggested that the two phases are initially the resin and hardener which subsequentially change into an intermediate alcoholic hydroxyl and secondary amine and finally the crosslinked solid. Pulsed broad bandwidth ultrasound propagation velocity and absorption changes during cure have been related to the change in physical state of the curing resin as it evolves from a viscous liquid to an elastic solid. The two techniques independently give a similar picture of the cure process, predicting cure events at the same times. Results suggest the cure follows distinct phases: an initial liquid stage where short polymer chains are formed followed by a second stage where longer molecules develop, a third stage where crosslinking between chains occurs and the adhesive begins to solidify, and a final stage when solidification completes.
Databáze: OpenAIRE
načítá se...