DIRECT EXPERIMENTAL-OBSERVATION OF THE CROSSOVER FROM CAPILLARY TO ELASTIC SURFACE-WAVES ON SOFT GELS

By using electrically excited surface waves we have studied the propag ation of hydrodynamic modes on the surface of agarose gels in the freq uency range 10(1)-10(3) Hz. Bulk rheological behavior has been also de termined in the frequency range 10(-2)-10(2) Hz by conventional rheome try. The propagation of two surface modes, capillary and elastic, is o bserved at low frequencies. Above a well defined crossover frequency, regular capillary behavior is observed. The experimental data are in e xcellent agreement with the theoretical predictions and the measured b ulk viscoelastic behavior. [S0031-9007(98)07302-5].