ADHESION INDUCED DEFORMATIONS OF A HIGHLY COMPLIANT ELASTOMERIC SUBSTRATE IN CONTACT WITH RIGID PARTICLES

Glass particles having radii between approximately 4.0 and 100 mu m we re deposited onto a highly compliant polyurethane substrate (Young's m odulus approximately 4.5 x 10(4) Pa). The resulting adhesion induced c ontact radii and heights of the menisci were measured using scanning e lectron microscopy. It was found that the contact radius varied as the particle radius to the 3/4 power. This is inconsistent with the 2/3 p ower law dependence predicted by adhesion theories which assume elasti c deformations, such as that proposed in the JKR model (Johnson, K. L. ; Kendall, K.; Roberts, A. D. Proc. R. Sec. London, A 1971, 324, 301) or the 1/2 power law dependence predicted by plastic deformation theor ies such as that advanced by Maugis and Pollock (Maugis D.; Pollock, H . M. Acta Metall. 1984, 32, 1323). These results are consistent with p revious contact radius measurements made using smaller particles on a more rigid elastomeric substrate (Rimai, D. S.; DeMejo, L. P.; Bowen, R. C. J. Appl. Phys. 1989, 66, 3574. DeMejo, L. P.; Rimai, D. S.; Bowe n, R. C. J. Adhesion Sci. Technol. 1991, 5, 959). The thermodynamic wo rk of adhesion between the glass particles and polyurethane substrate was estimated to be 0.044 J/m(2) and the experimentally determined hei ghts of the menisci are consistent with the predictions of the JKR mod el.