Self-Healing Wire Insulation
electrical and electronics
Self-Healing Wire Insulation (KSC-TOPS-51)
Microcapsules release healant that repairs minor cuts, nicks, and abrasions
Overview
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 which 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.
The Technology
Insulation is necessary on electrical wires in order to protect electrical systems from shorting. In high voltage systems such shorting can lead to sparking and fires. Many lives have been lost due to electrical wire insulation failure. Many man hours are also expended in the repair and inspection of electrical wiring in order to attempt to prevent wire failure. Wire insulation with a built in "self-healing" capability would greatly improve the safety of systems containing electrical wiring. Such insulation would require far less inspection and repair time over the lifetime of the system.
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. Microcapsules 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 in which the microcapsules are incorporated has good solubility with the solvent used to dissolve the polyimide which makes 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.
Benefits
- Reduced Maintenance - Self-healing of minor cuts, nicks, and abrasions on wire insulation can substantially reduce the need to perform inspection, troubleshooting, repair, and/or replacement of damaged wiring.
- Reduced Cost - Installation of wire with self-healing insulation can greatly reduce the cost of materials and labor required for the repair or replacement of damaged wiring.
- Improved Safety - Self-healing capability in wire insulation helps prevent shorts which can lead to sparking and conditions conducive to fires.
Applications
- Aerospace (Aircraft, Helicopters, Rockets, etc.)
- Defense (Missiles, Ground Vehicles, Ships, Submarines, Unmanned Aerial Vehicles, etc.)
- Automotive
Technology Details
electrical and electronics
KSC-TOPS-51
KSC-12539-2
KSC-13366
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Similar Results
Self-Healing Low-Melt Polyimides
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Polyimide Wire Insulation Repair System
A major limitation of current aerospace wire insulation is that it tends to crack and fray as it ages and is easily damaged. Generally, it is more cost-effective to repair wire insulation than to replace a section of the wire (or bundle) itself. Current repair methods include a tape wrap repair and a heat shrink repair. These methods have a number of drawbacks: susceptibility to vibration, fluid intrusion, and other mechanical stresses. The repair patch/material can loosen or separate, exposing the bare metal conductor or opening the polyimide insulation to more damage at the interface.
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Multi-layered Self-healing Material System for Impact Mitigation
This innovation utilizes a tri-layered structure, comprised of solid plastic front and back layers sandwiching a viscous, reactive liquid middle layer. Combined, this system provides rapid self-healing following high velocity ballistic penetrations. Self-healing in the front and back layers occurs when the puncture event creates a melt state in the polymer materials and the materials melt elasticity snaps back and closes the hole. The viscous middle layer augments the self-healing properties of the other layers by flowing into the gap created by a ballistic puncture and concurrently solidifying due to the presence of oxygen. Thus, this innovation has two tiers of self-healing: a puncture-healing mechanism triggered by the projectile and a second mechanism triggered by the presence of oxygen.
High-Performance Polyimide Powder Coatings
Powder coatings are used throughout industry to coat a myriad of metallic objects. This method of coating has gained popularity because it conserves materials and eliminates volatile organic compounds. Resins traditionally chosen for powder coatings have low melting points that enable them to melt and flow into a smooth coating before being cured to a durable surface. High-performance resins, such as Teflon, nylon, and polyimide, have not been found suitable for use in powder coatings because of their high melting points.
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Puncture-healing Engineered Polymer Blends
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