Study of the Hydrolytic Resistance of Glass Bottles under a High Fluctuated Weather Condition

Abstract

The occurrence of corrosion on glass surfaces results from the reaction between sodium in glass surfaces and water in the atmosphere under a certain condition. This reaction is promoted at high difference of humidity and temperature between a daytime and a nighttime especially in a rainy season. Glass surface treatments, for example by solutions, can improve the hydrolytic resistance. In the previous study, it was found that using 5wt% of alum gave the best effect to increase this property. The aim of this study was to examine the effect of closed and unclosed glass bottles during storage in a warehouse to the hydrolytic resistance. After treatment by 5wt% of alum, the amount of Na leached from the inner surfaces of glass bottles under simulated condition was determined. The weathering chamber was used to simulate the condition of a rainy season in Thailand with conditions set up and run in cycle. At first, the condition under the relative humidity (RH) value of 60 at 32°C was run for 12 hours, and then followed by RH of 80 at 25°C for 12 hours. The cycle was continued in the period of 8, 14, 21, 28, 53 days. After that the quantity of leached Na which is the conversion of hydrolytic property was analyzed by Flame-Atomic Absorption Spectrometry (FAAS). The results showed that the amount of Na leached from the untreated bottles was higher than the treated bottles around 5 times. It was also found that the quantity of leached Na from the untreated and closed bottles was raised with increasing time after 30 days while the untreated and opened bottles gave a rather constant result.