17. Mesurement of temperature dependence of specific volume of coal using gas pycnometry

Abstract

Glass to rubber transitions in four different kinds of coals ranging from lignite to bituminous, were examined by using gas pycnometry in which helium was used as a probe molecule. The specific volumes of the coal samples were measured in the temperature range between 323 and 423K. The specific volumes of the samples were increased with temperature due to their thermal expansion. The clear discontinuous points were observed at around 380K in temperature-specific volumes plots for Beulah Zap lignite and Upper Freeport coals, Suggesting that these coals have glass to rubber transition at this temperature.