W0193

Structure of Colloidal Silica Gels; Application of a Shear. H.J.M. Hanley, Physical and Chemical Properties Division, National Institutes of Standards and Technology, Boulder, Colorado, USA

From a scientific point of view gels are fascinating; even the question of what a gel is is not clear cut; elucidating its microstructure (the order and distribution of its constituent particles) is very much a current topic. Furthermore, from the practical point of view, the potential of a gel technology to fabricate advanced materials is enormous but a problem is to relate the properties of the final gel to its microstructure which can, in principle, be altered at each step of the gelation process. This talk will discuss how a shear, applied to a gelling system influences the gelation mechanism and the structure of the final gel. The results were possible because we have constructed an apparatus to measure simultaneously the structure by small angle neutron scattering and the viscometric properties of the gelling system.