Tuning the mechanical properties of MgO filled epichlorohydrin elastomer composites through in-situ alteration of filler structure using water as stimulus

Abstract

Water responsive elastomer composites were developed via in-situ chemical modification of the filler in the elastomer matrix where water molecules triggered a tunability of mechanical properties in elastomer composites. In this case, the in-situ transition of the active filler magnesium oxide (MgO) into magnesium hydroxide (Mg(OH)2) in water-swellable elastomeric blend consisting of epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (GECO) and ethylene oxide-propylene oxide-allyl glycidyl ether (GEPO) was studied. SEM and XRD validated the chemical and morphological transition of MgO to Mg(OH)2 in the hydrated elastomer composite. Additionally, on hydration, the treated elastomer's thermal stability is enhanced by 30 °C compared to the untreated elastomer composite. Stress-strain and DMA analysis results showed that the active filler's in-situ chemical transition in the matrix tuned the elastomer composite's mechanical properties. Tunability in Young's modulus by 221 %, M200 (Modulus at 200 % strain) by 80 %, and dynamic modulus at room temperature by 900 % are observed for 48 h water treated elastomer composite compared to untreated composite. Conceptually, this water responsive elastomer could find application in swell packers, marine sealants, adaptive medical implants and automobile industries.