The Mechanical Properties of Polyimide Films after Exposure to High pH

Wiring failures linked to insulation damage have drawn much attention in the aerospace industry and concerns have developed regarding the stability and safety of polyimide insulated electrical wire. Several polyimides were selected for evaluation for resistance to degradation by various aqueous alkaline solutions. The polyimides included commercially available films such as KAPTON®, APICAL®, LaRC™-TPI(Thermoplastic Polyimide) and UPI- LEX®R and S, as well as a number of experimental films prepared at NASA Langley Research Center, including LaRC™-ITPI(Isomeric Thermoplastic Polyimide) and LaRC™-CPI(Crystalline Polyimide). Thermally imidized films were studied for their retention of mechanical properties after exposure to high pH solutions under stressed conditions.