A new rapid screening method for silicones by size exclusion chromatography

A method is described of characterizing silicone extracts which provide the entire viscosity distribution of the extract instead of only a single average value. This distinction is very important, since it is the very low viscosity components of the silicone extract that are most likely to creep, thus causing relay contact failures and these components are not detected by methods that provide average viscosity values. In addition, since the lowest viscosity fractions are also the most volatile, this method also addresses the problem of gas-phase transport. The method described requires only standard chromatographic equipment and results can be obtained in a matter of minutes. The development of this method, including the principles underlying the determination of the viscosity distribution, is briefly described, followed by examples of its application and comparisons to other silicone-extract characterization methods.<>