GC056 Polyimide Coating

Fused silica has high tensile strength and typical wall thickness is around 25 µm. This makes columns flexible and easy to handle. Nevertheless, this material is subject to rapid corrosion and breakage, even at normal laboratory conditions. Therefore, a thin polyimide protective coating is applied outside the tubing as it emerges from the drawing oven. This polyimide covering, protects the fused silica from moisture and corrosion. This material, in fact, determines the maximum operating temperatures for columns, which is around 360ºC, and around 380ºC for short term operations. This coating darkens with age. Higher operation temperatures require the use of stainless steel-clad fused silica.

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