GEL-POINT STUDIES IN REACTING SYSTEMS BY SHEAR-WAVE DISPERSION MEASUREMENTS

A study of shear wave dispersion in a gelling system shows that marked changes in dispersion occur due to the viscoelastic liquid to viscoel astic solid transition. A theoretical study suggests that an immediate pre-gel combination of liquid-like and solid-like properties might be detected by shear wave dispersion measurements. Experimental work on a system which exhibits critical gel behaviour gives a high frequency wave dispersion in good agreement with theoretical predictions. The wo rk illustrates the interdependence of the development of the relaxatio n spectrum at low frequencies and the high frequency wave dispersion, and suggests that measurements of the latter might be used to determin e the gel-point in some systems. (C) 1997 Elsevier Science B.V.