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 a thermoplastic polymer for molecular scale healing is disclosed; the composition has the ability to resolve structural defects by a bio-mimetic close-then heal process. In use, the shape memory polymer serves to bring surfaces of a structural defect into approximation, whereafter use of the thermoplastic polymer for molecular scale healing allowed for movement of the thermoplastic polymer into the defect and thus obtain molecular scale healing. The thermoplastic can be fibers, particles or spheres which are used by heating to a level at or above the thermoplastic's melting point, then cooling of the composition below the melting temperature of the thermoplastic. Compositions of the invention have the ability to not only close macroscopic defects, but also to do so repeatedly even if another wound/damage occurs in a previously healed/repaired area.
1. A composition comprising:
a matrix of thermoset polymer;
programmed fibrous shape memory polymer which comprises the ability to contract when heated to above its shape recovery temperature; and,
means for healing at a molecular scale dispersed throughout said matrix.
2. The composite of claim 1 , wherein the shape memory polymer is a polyurethane shape memory polymer.
3. The composition of claim 1 wherein the fibrous shape memory polymer fiber is coated by a fixing agent.
4. The composition of claim 3 wherein the fixing agent comprises an epoxy supportive coating, and a protective coating applied prior to the epoxy coating which protects the shape memory polymer from chemicals used for the epoxy coating.
5. The composite of claim 1 wherein the fibrous shape memory polymer is in segments of at least the critical fiber length.
6. The composite of claim 1 wherein the fibrous shape memory polymer is woven or is formed as a cable.
7. The composition of claim 1 wherein the means for healing at a molecular scale is thermoplastic polymer.
8. The composition of claim 7 wherein the thermoplastic polymer is 40% or less of the volume of the composition.