Gas loss of insulating glass units under load: internal pressure controlled permeation test

Abstract

The edge-seal is the most important part of an insulating glass unit regarding the loss of insulating gases from the inter-pane space. Its long-term behavior is mainly defined by climate loads. Here, increasing stresses on the polymer sealants lead to chain-orientation. This introduces anisotropic materials properties. The strain causes macroscopic deformation of the edge-seal. Both effects might enhance the permeation rate, yet are not considered by the established testing standards. Therefore, the standard test to measure the gas loss rate under climate conditions has to be refined and extended. In this work, a new test setup is introduced which correlates the stress-strain behavior within the edge-seal with the gas loss rate of insulating glass units. Three different concepts are evaluated by means of the stress-strain state within the edge-seal as well as the needed dimensions and the manufacturing complexity of the test stand. As a result, the internal pressure controlled permeation test method appears to be the most suited. Finally, the measurement setup is realized as a prototype and optimized.