Crosslinking of loose insulating powders
Described herein are materials and methods useful in the field of insulation, including building materials, refrigeration, cryogenics, and shipping, amongst others. Advantageously, the provided materials and method provide low thermal conductivities and increased mechanical strength, allowing for efficient insulating in a diverse range of applications. The provided materials and methods include individual particles connected by a polymer network that links individual particles and may include hollow or evacuated capsules and various strengthening agents.
1. An insulating material comprising:
a plurality of insulating particles;
a polymer crosslinking the plurality of insulating particles, wherein the polymer comprises an adhesive;
wherein the plurality of insulating particles have a packing density greater than or equal to 50%;
wherein the boron-containing strengthening agent comprises triisopropyl borate, boron trichloride, trimethyl borate or a combination thereof.
2. The insulating material of claim 1 , wherein the insulating material has a thermal conductivity less than or equal to 9 mW/m-K.
3. The insulating material of claim 1 , wherein the insulating material has a maximum compressive stress greater than or equal to 0.10 MPa.
4. The insulating material of claim 1 , wherein the insulating material has a maximum compressive strength greater than or equal to 0.48 MPa at 10% deformation.
5. The insulating material of claim 1 , wherein the insulating material has a shear strength greater than or equal to 0.05 MPa.
6. The insulating material of claim 1 , wherein the insulating material has a tensile strength greater than or equal to 0.05 MPa.
7. The insulating material of claim 1 , wherein the polymer is deposited on an outer surface of the plurality of insulating particles at a thickness selected from the range of 5 to 10 monolayers.
8. The insulating material of claim 1 , wherein the adhesive comprises a cyanoacrylate.
9. The insulating material of claim 8 , wherein the cyanoacrylate comprises methyl cyanoacrylate, ethyl cyanoacrylate, butyl cyanoacrylate, octyl cyanoacrylate or a combination thereof.
10. The insulating material of claim 1 further comprising a plurality of reinforcing fibers.
11. The insulating material of claim 10 , wherein the reinforcing fibers comprises cellulose, a plant material, a second polymer, glass or a combination thereof.
12. The insulating material of claim 1 , wherein the plurality of insulating particles comprise a plurality of hollow capsules.
13. The insulating material of claim 12 wherein the plurality of hollow capsules comprise:
a plurality of small hollow capsules having a diameter selected from the range of 0.01 mm to 0.03 mm; and
a plurality of large hollow capsules having a diameter selected from the range of 0.1 mm to 1 mm.
14. The insulating material of claim 12 , wherein the hollow capsules have an internal pressure less than or equal to 0.001 atm.