Jason F. Patrick, Nancy R. Sottos (PI), Scott R. White (co-PI)Email: jpatric2@illinois.edu, n-sottos@illinois.edu, swhite@illinois.edu

Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign

A microvascular-based approach isadopted to autonomously repair blastdamage in structural sandwich panels.Self-healing materials are inspired byliving systems, in which minor damage(e.g., a bump or bruise) triggers anautonomic healing response. Wesuccessfully introduce vasculature intoboth the foam core and the wovenfiber reinforced composite face sheets.Preliminary experiments demonstratethe potential for full recovery (100%)of fracture properties in the foamcore. Work is in progress to achievehealing in the composite face sheets.

While external armor is designed toabsorb the primary energy from a blast,significant damage also occurs deepwithin a structure. This secondarydamage can impair function and lead tofailure even if the structure survives theinitial explosion. Autonomic healing ofthis secondary damage can significantlyimprove reliability and safety byproviding recovery of structuralintegrity. We are pursuing abioinspired microvascular strategy[4]

that offers the advantages of a virtuallyunlimited supply of healing agents inaddition to the capability of recoveryfrom multiple injury events. Ourapproach is transferable and consists ofmodifying components of a commercialcomposite sandwich panel shown toexhibit superior performance in recentshock tube experiments.[2] Energy isabsorbed through anticipated failuremechanisms and recovered forsubsequent loading cycles.

This material is based upon work supported by the U.S. Department of Homeland Security under Award Number 2008-ST-061-ED0001. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied of the U.S. Department of Homeland Security.

We have developed materials and techniques[1] forthe fabrication of 3D microvascular fiber-reinforcedcomposites, providing a conduit for self-healingapplications. Microvascular healing was successfullydemonstrated in a rigid, structural foam using anexpansive polyurethane (PUR) chemistry, ideallysuited for large damage volumes.

We intend to demonstrate the self-healingfunctionality of 3D microvascular fiber-reinforcedcomposites. Once the distinct, self-healingcapabilities of the foam core and composite facesheet components are established, a fully integratedstructural sandwich panel will be fabricated andevaluated through shock tube testing at theUniversity of Rhode Island.

[1] Esser-Kahn, et al. Three-Dimensional MicrovascularFiber-Reinforced Composites , Submitted, (2011).

[2] Tekalur, et al. Shock loading response of sandwich panelswith 3-D woven E-glass composite skins and stitched foamcore , Composites Science and Technology, 69, 736-753,(2009).

[3] White, et al. Autonomic healing of polymer composites,Nature, 409, 794-797, (2001).

[4] Toohey, et al. Self-healing materials with microvascularnetworks, Nature Materials, 6, 581-585, (2007).

Self-Healing Materials for Mitigation of Blast Damage

Technical ApproachAbstract

Relevance

Accomplishments Through Current Year

Future Work Other References

Publications Acknowledging DHS SupportOpportunities for Transition to

Customer

Patent Submissions

Our self-healing systems have beendesigned around pre-existing sandwichtechnology and thus, are easily amendableto commercialization. An industrial partner,3TEX, Inc., was responsible for weaving the3D fiber preforms in both the existing[2] andnewly developed microvascular[1] compositeface sheets. The PIR foam core material isthe same product found in the existingsandwich panel. The PUR healing agentsare a commercially available 2-part system.

“Micro-Vascular Network Materials and Composites for Forming the Materials,”

University of Illinois Invention Disclosure(2011)

Composite Sandwich Panel[2]

for Blast Protection

3D Woven CompositeFace Sheets

Polyisocyanurate (PIR)Foam Core

BioinspiredMicrovascular Healing[3,4]

1. Catalyst treated polylactide (PLA) monofilament woven into 3D glass fiber preform

2. Composite fabrication using Vacuum Assisted Resin Transfer Molding (VARTM)

4. First 3D microvascular fiber-reinforced composite capable of fluid transport for self-healing

3. PLA evacuation by heating high Tg composite at 210 C for 48 hrs under vacuum

Dual-Channel 3pt. Single EdgeNotched Bend (SENB) Specimen

diameter : 1 mm

spacing : 5 mm

A

B

Part A - (MDI) Part B - (Polyol) + catalysts, surfactants, blowing agents

Polyurethane (PUR) foam

Healed Fracture Plane

Virgin Material

Can achieve 100% recovery in fracture

properties!

Self-Healing Polymer Foam

0

1

2

3

4

5

6

7

0 500 1000 1500 2000 2500 3000

Lo

ad

(N

)

Displacement (µm)

Virgin I

Healed I (20 µL)

Virgin II

Healed II (20 µL)