Aging behavior of polyimide/acrylate coated optical fibers in harsh environments

Typically a polyimide coating thickness of 12 to 15 micrometers is applied to different optical fibers mainly for various high- temperature applications. Because this coating is so thin, handleability is an issue from the point of view of mechanical damage. To protect the polyimide coating from handling-related damage, a composite coating of polyimide and acrylate is typically applied to the optical fiber. We expose such coated fiber to deionized liquid water at 85 degree(s)C and to steam for durations of 100 d in water and 26 d in steam. When the strength of the fiber is measured after aging in water, there is a slight drop in strength; but, surprisingly, there is no change in strength after aging the composite-coated fibers in steam.