Synthesis of Scleroglucan-Smectite Composite Based on Porto Santo Bentonite

Abstract

In this thesis, a smectite rich bentonite ore deposit from Porto Santo Island (Portugal) was characterized and then applied to prepare clay-biopolymer nanocomposite material. Natural clay sample is mainly composed of Fe rich smectite, having also feldspar, calcite and magnetite-maghemite minerals. Both montmorillonite from the clay source repository (SWy-2) and the Porto Santo bentonite were used for the nanocomposite synthesis. An exocellular polysaccharide – scleroglucan was used as a biopolymer. The X-ray diffraction and transmission electron microscopy results show that smectite is well dispersed in the scleroglucan matrix with partial exfoliation. The study of various experimental parameters reveal that only the scleroglucan/clay mineral mass ratios determine the level of the clay sheets’ dispersion in the polymer matrix. Compared to SWy-2, the Porto Santo bentonite shows a smaller degree of dispersion within the polymer matrix, but nevertheless its potential outstanding mechanical properties could be of interest for further studies.