Effect of chemical structure on the water sorption of amine-cured epoxy resins

In this investigation, water sorption behaviour of six epoxy systems with different chemical structure of amines and epoxies were monitored at five temperatures ranging from 35 to 75 °C. The sorption process was analyzed by gravimetric measurements, positron annihilation lifetime spectroscopy (PALS), and attenuated total reflection Fourier transform infrared spectroscopy (ATR-IR). PALS measurements showed that the free volume fraction is not a decisive factor in governing the equilibrium water content, while the polarity of the system is the essential factor. ATR-IR curve fitting were consistent with the theoretical calculated results, and correlated to the diffusion coefficients from gravimetric measurements.