Volume 6, Issue 7 (July 2009)
Evaluation of the Durability Potential of Silyl Terminated Polyacrylate Based Construction Sealant
In this paper, we discuss the durability potential of silyl terminated polyacrylate based construction sealants. The durability and performance of a silyl terminated polyacrylate (STPA) based construction sealant have been evaluated in comparison to a typical silyl terminated polyether (STPE) and a silicone sealant in order to demonstrate the potential of the STPA sealant as a high durability, high performance construction sealant that is also suitable for glazing applications. The polyacrylate backbone of STPA polymer has higher durability, especially UV stability and heat resistance, than the polyether one of STPE polymer as shown by accelerated weathering tests using carbon-arc or superhigh irradiance xenon-light sources. Adhesion of the STPA sealant on glass was retained even after 10,000 h exposure to superhigh irradiance xenon-light [180 W/m2 (300–400 nm)]. The performance of the STPA based sealant has been compared to that of the STPE based sealant by testing according to several industrial International Organization for Standardization (ISO) and Japanese Industrial Standard (JIS) standards. The STPA based sealant conforms to a higher durability class specification than the STPE sealant, for example, the requirements of class 10030 are passed with the STPA sealant, while the STPE sealant passes only class 9030 as stipulated in JIS A 5758. Furthermore, a cyclic movement test of the STPA based sealant in a compression-extension machine shows no damage to the sealant even after 200,000 cycles of ±40 % movement at room temperature. This performance is much better than that of sealants based on other materials, such as STPE, polyurethane, polysulfide, and silicone. These evaluations suggest a high potential of STPA based sealant as durable elastomeric joint sealant, which can be used on a glass, including photocatalytic self-cleaning glass, which functions by decomposing organic materials and by providing a superhydrophilic surface.