| The effects of a number of inorganic and organic acids (HCI, HN03,
HCI04, CH3COOH, CI3CCOOH) on the peptization of aluminium
monohydroxide derived from aluminium secondary butoxide were
examined. The efficiency of peptization, given inversely by the
optical density of the sols, varied in the series HCI04 > HNOa > HCI
for inorganic acids and CH3COOH > CI3CCOOH for organic
acids. A similar series was also valid for the shrinkage pattern of the
sols during sol-gel transformation, pointing towards a proportionality
between colloidal particle size and the degree of flocculation. The
rate of escape of the volatiles, i.e. gelling time as a function of gel
volume, could be expressed by a linear regression equation with a
correlation coefficient r = -0.9658, indicating a strong relationship,
when gelation under the action of low concentrations of the acid was
ignored. |
