Polymeric Base

The base of photographic film is a transparent polymeric material upon which several thin layers of photographic emulsion are coated. When a flat polymeric film is bent to some fixed curvature, held at this state for some time, and then released, its curvature is observed to drop instantaneously to some non-zero value and then gradually decrease with time. This phenomenon is generally referred to as bending recovery. Bending of polymer films and the associated recovery phenomena are critical in vaious packaging, forming and finishing operations. One of the considerations in choosing material for film base is to achieve desired bending recovery.