Effects of Mean pressure on the behavior of a filled elastomer

The rheological behavior of an elastomer composed of a polyurethane rubber filled with granular potassium chloride is studied on the basis of a series of compression tests with superimposed hydrostatic pressure. It is suggested that behavior may be approximated by a linear anelastic response for relatively small strains until a marked change in structure occurs, and that further deformation involves shear-dependent dilatation which is strongly influenced by mean pressure. Theories are suggested which describe the experimentally observed behavior.