Water absorption in polyaminosiloxane-epoxy thermosetting polymers

Water absorption is a common problem in epoxy-based composites, especially in interfacial regions. In contrast to epoxy resins, silicones are hydrophobic materials. Modification of epoxy thermosets with silicones should improve physical properties because of decrease in water diffusion. Bisphenol-A diglycidyl ether (DGEBA) was cured with a synthesised aminopropyl perfunctionalised siloxane. Water absorption was analysed by different techniques, including near infrared (FTIR) water absorbance at 5200 cm−1 and gravimetry. Fick’s law diffusion coefficients were calculated. Swelling equilibrium of the resin was also analysed. Absorbed water catalyses the curing reaction strongly, allowing to reach high conversions.