PREPARATION AND PROPERTIES OF POTASSIUM-VERMICULITE FILMS

Flexible films of vermiculite have been prepared from aqueous suspensi ons after swelling by cation exchange and mechanical delamination. Two different swelling cations, lithium and butylammonium, have been inve stigated. The degree of swelling and delamination during the suspensio n preparation was characterized by the percentage of water reabsorbed by dried clays and the adsorption of methylene blue. The vermiculite s aturated with lithium ions is more easily delaminated but contains mor e water than those saturated with butylammonium. Good quality coherent flexible films could be prepared from both the lithium and butylammon ium exchanged vermiculites but the high percentage of water found in t he films has a detrimental effect on their dielectric properties. To r educe the amount of water in the exchanged vermiculites a second ion e xchange with potassium, a less hydratable cation, was investigated. Fi lms prepared after exchange with potassium showed significant improvem ents in their dielectric properties, with a dielectric constant epsilo n around 10 and a dissipation factor tan delta around 0.06 at 25 degre es C and a frequency of 1 kHz.