Abstract
A study of elastic behaviour under shear stress below the yield value has been made on seven different gels covering a wide range of chemical constitution. The static rigidity of a gelatine gel was found to increase with temperature in accordance with the kinetic theory of elasticity for long-chain polymers, and a similar variation was found in the case of a bentonite gel. This suggests that even when the material dispersed in a gel consists of discrete particles a loose chain structure is formed which is mechanically similar to that existing in a polymer gel. The theory of elastic loss for solid cross-linked polymers developed by Kirkwood would thus appear to be applicable to these gels. This has been tested by a series of measurements on the dynamic rigidity and dynamic viscosity of all seven gels together with observations of their creep and static rigidity. In four cases the results are consistent with this theory, but in the others it appears that the spectrum of retardation times is broader than the theoretical spectrum.