Edge-Seal Effects on Service-Life and Utility Value of Dual-Sealed Insulating Glass Units

Andreas T. Wolf

The service life of a sealed insulating glass unit (IGU) critically depends on the perfect functioning of the edge-seal under all environmental and service loads. The water vapour permeability of the secondary insulating glass sealant plays only a subordinate role in the life expectancy of a dual-sealed IGU, since the resistance of the edge-seal to water vapour diffusion is determined almost exclusively by the polyisobutylene primary seal. However, great importance must be attached to the viscoelastic properties of the secondary insulating glass sealants, particularly to their tensile stress behaviour and their elastic recovery under service conditions, as these properties affect the ability of the primary seal to function.

The resistance of the edge-seal to gas diffusion is influenced by the permeabilities of both primary and
secondary seals. IGUs with very low gas loss rates, meeting the stringent requirements of the German and new European standards, can be produced by proper selection and design of the edge-seal components, particularly by either minimising or properly accommodating the movements occurring in the edge-seal as a result of the thermal stresses.

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The Authors

	Dr. Andreas Wolf Scientist, New Business Development Dow Corning GmbH Dr. Andreas Wolf is a Scientist and New Opportunity Development Specialist for the Global Construction Industry at Dow Corning, Wiesbaden, Germany. He has lectured intensively in Europe, North Amer... Read more
	Dr. Andreas Wolf Dr. Dow Corning S.A. Read more