科研之友
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摘要
Silica sols are produced with sodium silicate and sulfuric acid by their neutralization. We have previously reported that both the onset time of the gelling and the sol-gel transition are strongly affected by the preparation conditions of acid silica sols. In this study, we evaluated the effect of the temperature and pH on the rheological properties of silica gels by both the dynamic viscoelastic measurement and the creep test in order to probe the structure of gels during aging. The results indicate that the heating plays a role in the fast-forwarding of the gelling time. In contrast, increasing in pH affect not only the gelling time but also the elastic modulus of the four-component model adopted for the silica gel. The mechanism of the particle bonding might be related to pH, and the predicted bonding images are presented.
