Rheological and Mechanical Properties of Alkoxy Type Silicone Sealant

摘要

Silicone sealants are composed of polymer, plasticizer, crosslinker, catalyst, and filler. Types and compositions of components are effected on sealant performance. Silicone sealants are distinguished according to the crosslinkers as acetoxy, oxime, or alkoxy types. Acetoxy type silicon sealant is one of the most widely used silicone sealant industry. However, it suffers from problems of corrosion on some metals and alkaline substrates. Also, acetic cure sealants have found disfavor owing to the odor of the acetic acid generated during cure. Oxime type silicon sealant has acceptable cure rates and is non-corrosive by acid/base reactions. However, the methylethylketoxime by-product can complex with some metals such as copper to generate unwanted colors, and if allowed to accumulate, the ketoxime vapor can induce crazing on certain plastics such as polycarbonate. This makes it unsuitable in certain applications. Thus, alkoxy types are readily available. It releases methanol as a by-product, which is non-corrosive to most substrates and is not particularly offensive in odor. But, it is much less reactive and requires specialized catalyst systems to achieve adequate cure rates. In this study, we investigated effects of component types and ratios on alkoxy type silicone sealant performance.