Material Characterization of Silicone Sealants

Silicone sealants were analyzed using dynamic shear rheometry (DSR) and numerical analysis to determine if a method could be developed that would provide the basis for a performance-based specification. The research used a three-phase approach including DSR analysis of aged and unaged sealants, numerical model development using the DSR data as input, and laboratory tension experiments for model verification. Results of the investigation indicated that the average material properties determined through DSR and laboratory tensile testing appeared to be representative of the “true” material properties for elongations of up to 25 percent. The results were less accurate for 50 percent elongation but still acceptable. The DSR testing could be related to field performance; however, conducting several tests on multiple samples to develop a discrete stress-relaxation spectrum for numerical analysis would not be feasible for most users. Instead, two test temperatures should be selected for DSR testing based upon the maximum and minimum in-use temperature the sealant would be exposed to for a given application.