Structure and mobility in highly viscous silicate solutions
This thesis is concerned with the investigation of highly condensed, highly viscous silicate systems by means of NMR methods (mainly 29si-NMR investigations). The work focused on silicate solutions containing colloidal particles in sol and gel form with the interest of the work centred on the systems near the sol/gel-transition. Quantitative information about the behaviour of silicate species in these silicate systems is presented and some information about die role of protons and sodium cations in the silicate solutions is provided The structure of the colloidal material existing in these highly condensed silicate systems is investigated along with the behaviour of colloidal particles in several situations such as decreasing alkalinity or changing Si02-concentration. Additionally an idea of the range of particle sizes in the colloidal material in highly-condensed silicate solutions has been obtained. The dynamics of the silicate systems were studied in terms of rotational mobility as well as diffusive motion. Exchange processes between silicate species were monitored using ID-exchange spectroscopy. An investigation of the influence of additives, in particular surfactants, on highly condensed silicate systems was carried out by adding representative surfactants of the categories cationic, anionic and non-ionic.