Published: Jan 2004
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The use of extruded and molded silicone rubber attached with a one-part silicone sealant is becoming a popular method of curtainwall and general building renovation. The use of extrusions provides an aesthetically pleasing restoration method for sealing out water from the outside of the building. The extrusions and molded parts have become popular for restoration because of the ease and speed of installation. An economical fix for leaking walls coupled with the aesthetics has provided building owners a good solution.
As with any restoration solution, the question of durability and speed of adhesion has been asked. This paper presents data on the cure and adhesion rate of the one-part silicone sealants used in the attachment of the extruded and molded parts by reporting data on the strength and modulus with time using a modified ASTM C1135 test method. Also data is presented on the durability of these bonds using this test method and exposing the samples to 2700 hours of QUV accelerated weathering. Test results are reported for samples that are comprised of glass and fluorocarbon painted aluminum substrates. Silicone rubber extrusions with Shore A durometer hardness of 30 and 56 are evaluated. These samples are evaluated at several different cure times (4 hours, 14 hours, 24 hours, 7 days, 3 weeks) and also subjected to various thermal and atmospheric conditions (heat, cold, QUV exposure, and water immersion).
Conclusions are that the silicone adhesive can provide adequate cure and strength in less than 24 hours to withstand typical stresses incurred during the first day's movement. The accelerated weathering shows no effect on the bonds of the silicone adhesive sealant to the extrusions used in this study. Hence, the method of restoration currently used with these parts is expected to perform as a long-term weatherproofing solution similar to the use of silicone sealants as structural glazing and weathersealing applications.
silicone rubber extrusions, silicone rubber molded parts, remedial weathersealing, adhesion rate, durability
Associate Industry Scientist, Dow Corning Corporation, Midland, MI
Application Sales Engineer, Dow Corning Corporation, New Milford, CT