Optical Characterization of Tungstic Acid around Gelation Time

Optical characterization of tungstic acid during gelation process was performed by observing the evolution of the angular dependence of the scattered light intensity and the penetration length of the light beam. In the light scattering experiments, the anisotropic increase or decrease in the scattered-light intensity was observed after the gelation time (tg). In the observation of the penetration length of the light beam, the drastic change in the decreasing rate of the penetration length was found also around tg. The light intensity scattered from the positions adjacent to the incident light beam increased remarkably after tg. Judging from these characteristic features around tg, the light scattering properties seem to be closely correlated with the formation of the network in the later stage of the gelation process.