Compositions incorporating silica fibers
Embodiments of the invention include articles incorporating fibrous fragments of mats of silica fibers and methods for producing such articles. The fiber mats may be formed via electrospinning of a sol gel produced with a silicon alkoxide reagent, such as tetraethyl ortho silicate, alcohol solvent, and an acid catalyst.
1. A method of making a composition, the method comprising:
electrospinning a sol-gel to form a non-woven mat of silica fibers;
fragmenting the mat to form a plurality of fibrous fragments each comprising an intertwined collection of silica fibers; and
mixing the fibrous fragments into a liquid composition to form a modified composition.
2. The method of claim 1 , wherein the liquid composition comprises a paint, an epoxy, a urethane, or an adhesive.
3. The method of claim 1 , wherein the sol-gel is prepared with tetraethylorthosilicate (TEOS).
4. The method of claim 1 , further comprising, prior to electrospinning the sol-gel, producing the sol-gel from an initial sol comprising 70% to 90% TEOS by weight, 8% to 25% ethanol by weight, an acid catalyst, and water.
5. The method of claim 4 , wherein producing the sol-gel comprises ripening the initial sol for at least 2 days at a humidity of 40% to 80% and a temperature of 50° F. to 90° F.
6. The method of claim 5 , wherein the initial sol is ripened for at least 3 days.
7. The method of claim 5 , wherein the sol-gel is electrospun when the weight of the sol-gel ranges from 10% to 60% of a starting weight of the initial sol prior to ripening.
8. The method of claim 5 , wherein the sol-gel is electrospun when production of ethylene vapor therefrom ranges from 10% to 40% relative to the initial sol prior to ripening.
9. The method of claim 4 , wherein the initial sol is not exposed to a temperature of over 150° F. before or during production of the sol-gel.
10. The method of claim 4 , wherein the initial sol is not exposed to a temperature of over 100° F. before or during production of the sol-gel.
11. The method of claim 1 , wherein the fibrous fragments have an average size between approximately 20 μm and approximately 200 μm.
12. The method of claim 1 , wherein the fibers within the fibrous fragments have diameters ranging from approximately 50 nm to approximately 5 μm.
13. The method of claim 1 , wherein the fibers within the fibrous fragments have diameters ranging from approximately 200 nm to approximately 1000 nm.
14. The method of claim 1 , further comprising applying the modified composition as a coating to a solid object.
15. The method of claim 14 , further comprising applying heat to the coated solid object.
16. The method of claim 1 , further comprising molding the modified composition into a solid object.
17. The method of claim 1 , wherein the mat is fragmented by milling or grinding.
18. The method of claim 1 , wherein fragmenting the mat comprises rubbing the mat through one or more screens or sieves.
19. The method of claim 1 , wherein fragmenting the mat comprises rubbing the mat through a plurality of screens or sieves each having a different mesh size.
20. The method of claim 1 , wherein, prior to electrospinning, the sol-gel is not exposed to a temperature of over 150° F.
21. The method of claim 1 , wherein, prior to electrospinning, the sol-gel is not exposed to a temperature of over 100° F.
22. The method of claim 1 , wherein a thermal resistance per unit area of the modified composition is greater than a thermal resistance per unit area of the liquid composition.
23. The method of claim 1 , wherein the liquid composition is a paint, the paint comprising a binder, one or more diluents, and one or more pigments or dyes.
24. A method of making a composition, the method comprising:
ripening an initial sol to produce a sol-gel, wherein the initial sol (a) comprises 70% to 90% TEOS by weight, 8% to 25% ethanol by weight, an acid catalyst, and water, and (b) is ripened within an enclosure, the enclosure comprising, for controlling an atmosphere within the enclosure during ripening of the initial sol, (i) a humidity sensor and a humidifier configured to control the humidity to a level of 40% to 80%, and (ii) a vent and a fan configured to draw gases away from the initial sol;
electrospinning the sol-gel to form a non-woven mat of silica fibers;
fragmenting the mat to form a plurality of fibrous fragments each comprising an intertwined collection of silica fibers; and
mixing the fibrous fragments into a liquid composition to form a modified composition.