(A) study on the fabrication and properties of epoxy/layered silicate nanocomposites

Abstract

In this dissertation, we prepared the organoclays which can form chain-extended organifiers and introduced the organoclays in epoxy/layered silicate nanocomposites. The epoxy/layered silicate nanocomposites were synthesized by in-situ polymerization. The effect of the chemical structure of the organifiers on the properties of the organoclays such as d-spacing, ion-exchanged fraction was investigated. The effects of the organoclays on the properties of the nanocomposites such as the morphology, glass transition temperature, thermal stability, tensile properties and fracture toughnessof the nanocomposites were also investigated. In chapter 2, we synthesized three kinds of the polymeric surfactant organifiers which have urethane group in the backbone based on MDEA(N-methyl dietanol amine) and relatively high molecular weight to enlarge d-spacing; one(P2K) has hydroxyl end-group to react with epoxy groups during polymerization and the others(J400, J230) have amine end-group to react with epoxy groups during polymerization. That is, because the polymeric surfactants were synthesized to have amine end-group, they can react with epoxy groups during the polymerization of epoxy. Three kinds of Organoclays(OC P2K, OC J400 and OC J230) were prepared by cation exchange reaction between the pristine montmorillonite and excess organifier. And clay-amine mixture organoclay(OC HMDA14) was also prepared using a brabender mixer, Cloisite20A and 14wt% of HMDA contents were mixed. The effect of the chemical structure of the organifiers on the properties of organoclays was investigated. The d-spacing of pristine montmorillonite was increased by introducing the organifier from 1.18nm to 1.98nm for OC P2K, 1.74nm for OC J400, and 1.37nm for OC J230 and 1.33~4.14nm for OC HMDA14, respectively. The ion-exchanged fraction(IEF) of OC P2K was 0.448, that of OC J400 was 0.332, and that of OC J230 was 0.288, respectively. These values meant that for the case of OC P2K, 44.8% of Na cati...