Sealants

Abstract

Abstract Sealants are materials installed in gaps or joints to prevent water, wind, dirt, or other contaminants from passing through the joint or gap. They are commonly rated by their movement ability. High movement sealants such as silicones, urethanes, and polysulfides typically accommodate joint movement of 25% or higher. Acrylic sealants are commonly used in joints where movement is 5–15% and no higher than 25%. Butyl sealants are used in applications with movement of \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${<{\hskip-0.167em}{\hskip-0.167em}12.5{\%}}$\end{document} . Each sealant type's base polymer provides inherent properties that find use in specific applications. Silicones are resistant to weathering and are used in applications where longevity is a prime concern. Urethanes are tough, abrasion‐resistant, with good adhesion to many substrates, thus allowing many applications in weatherproofing, especially in high abuse areas. Polysulfides have superior chemical resistance and find wide use in aircraft applications. Latex acrylics have good weatherability, low cost, and are easy to use, making them popular with consumers in nondemanding applications. Polyisobutylene sealants have low moisture vapor permeability and high tack, which are necessary for automotive and insulating glass applications.