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Sealants and Adhesives

1.0 INTRODUCTION

Most sealants are used in exterior applications, hence, they must be
deformable, have good recovery properties, and should have good overall
elastic properties. Many sealants used in the construction industry are
required to maintain functional performance characteristics over many
years. While in service, sealants are exposed to environmental factors such
as UV radiation, water, oxygen, and thermal cycling. Depending on which
face of the building sealants are placed, type of substrate, and geographic
region, they may be exposed to extreme environmental conditions, stress,
and strain gradients. Hence, sealants are susceptible to weather-induced
degradation. In general, degradation involves both chemical and physi-
cal processes with the chemical reactions usually preceding the physical
process. [1]
Weathering of construction sealants is an issue of importance not
only to sealant formulators, manufacturers, and specifiers, but also to
contractors and users. Sealants can fail due to weather exposure and aging.
This type of failure is often characterized by discoloration and crazing
and/or stiffness of the sealant surface and is a result of the individual or

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