Recently a statistically based model has been created to predict the change in modulus for a sealant exposed to outdoor weathering. The underlying high precision data supporting this model was obtained using the NIST SPHERE (Simulated Photo degradation by High Energy Radiant Exposure). The NIST SPHERE can independently precisely control each of the four primary weathering conditions: Temperature, Humidity, Ultraviolet Radiation and Mechanical Loading. The time-dependent modulus of the sealant samples were characterized using ASTM C1735-11 before and after each exposure. The resulting statically based model produces two major results: a statistical determination of the importance of each of the weathering conditions and the ability to generate a prediction of modulus change for any location, if a historical weather file is available. These two sealant models have shown that all four weathering factors, listed above, are significant contributors to modulus change in sealant. Additionally, the geographical predictions allow for independent verification of these models.
Citation: Natural and Artificial Ageing of Polymers
Pub Type: Journals
Outdoor exposure, polymer degradation, sealant, NIST SPHERE, modulus