Abstract
On the purpose of obtaining fundamental data necessary for application of water glass as alkali silicate soluble in water for inorganic adhesives and surface coating materials, hardening processes of films of various types of water glass (MO2 · nSiO2 ; M = Na, K, Li) coated on steel plates, asbesto scement boards and cardboards were examined under controlled constant condition (20 °C, 60 % R. H.) by reflection-absorption type infrared spectroscopy. Water resistance of various types of films hardened at high temperatures were examined by the change with time of the weight loss under immersion in 50 °C hot water and the change with time of the concentration of Na + ions solved in hot water by flame photospectroscopy. It was found that hardened films of water glass are assinged as the most fundamental inorganic polymers having siloxane molecular structures, and that they deteriorate in water by depolymeriazation process. The weight loss of fims in immersion in 50 °C obeys the parabolic law concerning time involving a constant term, which shows a certain induction period before the weight loss occurs. Based upon consideration and comprehension of these experimental results, theoretical dynamic analysis are carried out on the deterioration mechanisms, and the parabolic law concerning time involving a constant term is derived.
