ABSTRACT
Elastomeric based sealants, used to seal moving joints on the exterior of buildings, undergo diurnal cycles of movement superimposed on a yearly seasonal cycle. Hence, they are subject to movements that repeatedly extend and compress the sealant, and this cyclic movement may eventually cause the rupture of the seal due to fatigue of the elastomer. The fatigue resistance of elastomers has been related to that of their tearing resistance and cut growth characteristics. In this study, the dynamic cut growth characteristics of silicone-based elastomers were evaluated to gain an understanding of the phenomena of cyclic fatigue in these types of products and its relation to the durability of sealed joints. Two sets of sealants were cast, each having thin film specimens into which cuts has been intruded at one edge of the film. The first set was used to establish the relationship between the rate of deformation movement and the strain energy density within the specimen. The second set was subjected to cyclic testing from which the intrinsic dynamic cut growth parameters were obtained. Analysis of the cut growth characteristics was undertaken using strain-fatigue life plots from which the durability of the elastomers could be ascertained. Results indicate that the methods can potentially be used to assess the service life of sealant materials and provide a basis for developing an accelerated fatigue test for sealants.
