Gas-Sensing Composite Materials Based on Graphite and Polymers

A series of composite materials (CMs) based on polymers (polyethylene, polytetrafluorethylene, polyvinylchloride) and non-modified thermally expanded graphite (EG) and SiO2-modified EG have been prepared. Graphite contents in the CM vary from 0 to 100 wt% and modifier contents from 0 to 50%. The structural, electrical, and gas-sensing properties of CM have been studied. An influence of polymer nature, EG modifications by SiO2 on percolation processes, percolation threshold values (ΘC), and resistivity of obtained systems have been investigated. An influence of gaseous species (acetone, toluene, ethanol, ammonium, diethyl ester, propane, ozone) on the electric resistance of such CM has been analyzed. It is shown that by varying the type of polymer, the composition of the composites, and modification of the EG surface by SiO2, studying the effect of these on the shape of adsorption curves, velocity of adsorption–desorption process, selectivity of the CM to an influence of various substances, and other properties is possible. Uses of obtained materials as sensitive elements of sensors for determination of some gaseous compounds have been proposed.