Self-healing composite of thermoset polymer and programmed super contraction fibers
A composition comprising thermoset polymer, shape memory polymer to facilitate macro scale damage closure, and methods for molecular scale healing are provided. The composition can resolve structural defects by a bio-mimetic close-then heal process. In use, the shape memory polymer can provide molecular scale healing in a structural defect. The methods for molecular scale healing can include heating a composition including a thermoplastic such as fibers, particles or spheres to a level at or above the thermoplastic's melting point, then cooling of the composition below the melting temperature of the thermoplastic. The compositions have the ability to close macroscopic defects repeatedly even if another wound/damage occurs in a previously healed/repaired area.
1. A method for closing and healing a wound in a composite comprising a matrix of thermoset polymer, programmed shape memory polymer fiber that contracts at temperatures above its glass transition temperature, and thermoplastic polymer dispersed throughout said matrix, said method comprising steps of:
a. heating an area comprising a wound to a temperature above the glass transition temperature of the shape memory polymer fiber, whereby the shape memory polymer contracts and achieves some closure of the wound;
b. heating an area of the composite comprising the wound to a temperature above the melting temperature of the thermoplastic material whereby molten thermoplastic material flows into the wound; and,
c. cooling the matrix below the melting temperature of the thermoplastic, whereby the thermoplastic solidifies and heals the wound at a molecular scale.
2. The method of claim 1 wherein step a. and step b. take place concurrently.
3. The method of claim 1 wherein each of step a. and step b. take place below the decomposition temperature of the thermoset material.