Freezing and Melting Temperature Hysteresis of Water in Porous Materials: Application to the Study of Pore Form

Summary A theory is developed for the influence of pore form on the equilibrium freezing and melting temperatures of water in porous materials. This is supported by calorimetry and uses the hysteresis between freezing and melting temperatures for two clays and undried synthetic organic textile fibres in which the pore geometry is that of intersecting cylinders. For most water‐saturated clay systems, analysis of the low temperature endotherms gives a better appreciation of the pore size distribution than analysis of the exothermic data, unless the width of rectangular pores is known.