Water Vapor Sorption of Package Sealants

A unique system, designed for simultaneously measuring mass change and residual gases of samples loaded from a controlled environment, was used in conducting outgassing and water vapor adsorption-desorption experiments on sealing glasses. Owens-Illinois XS-1175, a vitreous sealing glass, was glazed in vacuum, air, nitrogen and oxygen and Owens-Illinois CV-ll, a devitrifying sealing glass, was glazed in vacuum. The outgassing products for both glasses during glazing were primarily water vapor and carbon dioxide. After glazing, the glasses were exposed to 1.33 kPa (13,150 ppmv) of water vapor for 1 h at 25°C to measure the amount of water sorbed. The mass gains due to water uptake of XS-1175 glazed in vacuum, air and nitrogen were similar, ranging from 0.0044 to 0.0058% by sample weight. On the other hand, the mass gain due to water sorption of the sample glazed in oxygen was significantly less, 0.0005%. Scanning electron micrographs of the vacuum and oxygen glazed samples showed that the glass glazed in vacuum was very porous, appearing sponge-like in nature, while the oxygen glazed glass had a much less porous surface. In addition, during a water vapor exposure the mass gain of CV-ll, a devitrifying glass, was about 5 times greater compared with XS-1175, a vitreous glass glazed under similar conditions. Commercially glazed XS-1175 and KC-1 black ceramic lids were heated to 4300C to measure mass changes and outgassing products during sealing. Initially, water vapor and carbon dioxide were the major volatile components outgassed.