A time-dependent expression for thixotropic areas. Application to Aerosil 200 hydrogels

Experimental determination of the areas enclosed under the up curve, sigma = sigma((gamma) over dot), corresponding to time zero, and the down curve, which would be obtained following complete rheodestruction of the system st ructure, is not an easy matter. In the present study a semi-empirical proce dure for calculating the hypothetical values of these parameters is propose d. With these parameters it is possible to obtain a time-dependent expressi on for the thixotropic areas, S-T. This procedure has been applied to the s tudy of the thixotropic behavior of Aerosil 200 hydrogels at different conc entrations. The comparative analysis of these systems has been realized by studying the relative thixotropic areas and relative thixotropic rates that are obtained from S-T. (C) 2000 Wiley-Liss, Inc.