NASA’s Kennedy Space Center is seeking commercial partners for licensing or further development of a novel high-performance, flexible, low-melt polyimide film with self-healing properties. The self-healing properties of the film are provided by embedded microcapsules containing a solvent-soluble polyimide. When cut or otherwise damaged, these capsules release their contents, which dissolve and heal the damaged area.
Aerospace and ground vehicles often contain miles of high-performance electrical wire insulation that are prone to damage from abrasion and cuts during vehicle operation and maintenance. Large portions of this wire are often buried within the vehicle framework, making it very difficult and time-consuming to locate and repair damage. Incorporation of a self-healing capability in the insulation of this wire would provide self-repair of minor nicks, cuts, and abrasions without maintainer intervention, and help reduce the danger of electrical shorts that could lead to sparking and fires.
Polyimides such as Kapton are an integral part of high-performance electrical wire insulation. Traditional polyimides are very inert to solvents and do not melt. A new set of polyimides, developed for use as films for the manual repair of high-performance electrical wire insulation, have a low melting point and can be dissolved in special solvents. These properties can be taken advantage of in self-healing polyimide films. Micro capsules containing a solvent-soluble polyimide are prepared using industry-standard inter-facial or in situ polymerization techniques. These capsules are then incorporated into a low-melt polyimide film for use as either a primary electrical wire insulation, or as one of several layers of a composite wire insulation.
The low-melt polyimide film substrate has good solubility with the solvent used to make up the fluid inside the microcapsule. Such a capsule-filled insulation, when cut or otherwise damaged, will result in the release of the capsule contents into the cut or damage area. The solvent then dissolves a small amount of the surrounding polyimide insulation, but will also begin the process of evaporation. The combination of these two processes allows for excellent intermingling of the healant and the surrounding substrate, resulting in a repair with superior bonding and physical properties.
This technology has potential applications in aerospace for aircraft, helicopters, and rockets; defense for missiles, ground vehicles, ships, submarines, and UAVs; and automotive.