ABSTRACT
Understanding the effects of environmental and chemical composition factors on the long term degradation of silicone sealants allows for better design and use of these materials. The work described herein examines the effects of water, water vapour, UV, heat and ambient ageing conditions on some commercial and lab prepared sealant properties. In addition, designed experiments were conducted to identify the effects of composition factors such as filler, catalyst or adhesion promoter levels on the ageing of oxime silicone sealants. The effects of exposure were evaluated through measurement of changes in strength, modulus, extensibility, hardness and apparent crosslink density. Changes in both sealant composition and environmental factors show effects on ageing rates and behaviours. The results hint at the existence of complex multiple mechanisms of change, sometime occurring with opposing effects.
