SIMULATION AND SANS STUDIES OF GELATION UNDER SHEAR

Computer simulations of a two-dimensional Lennard-Jones fluid undergoing spinodal decomposition are reported for the system subjected to planar Couette Bow. Key results are the images of the atomic structure and plots of the corresponding pair correlation functions. A companion small-angle neutron scattering (SANS) study of shear-influenced gelation in colloidal silica suspensions at volume fractions phi = 0.1, 0.12, 0.18, and 0.24 is discussed. It is found that the scattered intensity-wave vector curves from the unsheared gels obey a power law for phi < 0.24. At higher volume fractions, the power law does not seem to be followed, Shear, however, induces an apparent fractal structure in the gel at phi = 0.24. Results from the computer and the SANS experiments indicate that the spinodal decomposition process and the gelation mechanism have features in common.