Da. Donatti et Dr. Vollet, EFFECTS OF HCL ON THE ULTRASOUND CATALYZED TEOS HYDROLYSIS AS DETERMINED BY A CALORIMETRIC STUDY, Journal of non-crystalline solids, 208(1-2), 1996, pp. 99-104
The acid catalyzed and ultrasound stimulated hydrolysis of solventless
tetraethoxysilane-water mixtures was studied at 39 degrees C as a fun
ction of HCl added to the mixtures (log[HCl](-1) ranged from 0.8 to 2.
0). The reaction was carried out in a specially designed device, in wh
ich a steady state heat flow is maintained, while sonication is taking
place, if no reaction is expected to occur. The exothermal hydrolysis
reaction causes an increasing temperature (Delta T-t) as a function o
f the reaction time, t. The isothermal hydrolysis rate constant, k, ha
s been evaluated from the experimental Delta T-t versus t data, after
corrections for the increasing temperature effects, by using a method
resulting from our theoretical modeling based on a dissolution and rea
ction mechanism. The hydrolysis rate constant fits closely a k proport
ional to [H+] law as expected for this kind of hydrogen-ion catalyzed
reaction.