Heat Resistant Aerogel Materials
The present disclosure provides an aerogel composition which is durable and easy to handle, which has favorable performance in aqueous environments, and which also has favorable combustion and self-heating properties. Also provided is a method of preparing an aerogel composition which is durable and easy to handle, which has favorable performance in aqueous environments, and which has favorable combustion and self-heating properties. Further provided is a method of improving the hydrophobicity, the liquid water uptake, the heat of combustion, or the onset of thermal decomposition temperature of an aerogel composition.
1 . A reinforced aerogel composition comprising:
a reinforcement material comprising fibers or foam;
an inorganic aerogel comprising siloxy polymers, the inorganic aerogel incorporated with the reinforcement material;
one or more alkyl hydrophobic groups covalently bonded to at least some silicon of the siloxy polymers of the inorganic aerogel; and
wherein:
the reinforced aerogel composition is hydrophobic, having a liquid water uptake of 40 wt. % or less as measured according to ASTM C1511 or ASTM C1763; and
the one or more alkyl hydrophobic groups covalently bonded to at least some of the silicon of the siloxy polymers have an onset of thermal decomposition of no less than 525° C.
2 . The reinforced aerogel composition of claim 1 , wherein at least some of the one or more alkyl hydrophobic groups comprise a methyl group.
3 . The reinforced aerogel composition of claim 1 , wherein at least some of the one or more alkyl hydrophobic groups covalently bonded to at least some of the silicon of the siloxy polymers comprise methylsilyl groups.
4 . The reinforced aerogel composition of claim 1 , wherein the silicon covalently bonded to the one or more alkyl hydrophobic groups is trifunctional silicon or quadfunctional silicon.
5 . The reinforced aerogel composition of claim 4 , wherein:
the trifunctional silicon comprises T 1 species, T 2 species, and T 3 species in a relative proportion of T 1-2 :T 3 species of from 0.2 to 0.4; and
the quadfunctional silicon comprises Q 2 species, Q 3 species, and Q 4 species in a relative proportion of Q 2-3 :Q 4 species of from 0.8 to less than 1.5.
6 . The reinforced aerogel composition of claim 1 , wherein:
a weight proportion of the one or more alkyl hydrophobic groups relative to a weight of the reinforced aerogel composition is a hydrophobic organic content; and
the hydrophobic organic content of the reinforced aerogel composition is from 1 wt. % to 15 wt. %.
7 . The reinforced aerogel composition of claim 6 , wherein the hydrophobic organic content is from 1 wt. % to 5 wt. % of the reinforced aerogel composition.
8 . The reinforced aerogel composition of claim 6 , wherein the hydrophobic organic content is from 2 wt. % to 10 wt. % of the reinforced aerogel composition.
9 . The reinforced aerogel composition of claim 6 , wherein the onset of thermal decomposition of the one or more alkyl hydrophobic groups covalently bonded to at least some of the silicon bonded to the one or more alkyl hydrophobic groups is no less than 550° C.
10 . The reinforced aerogel composition of claim 1 , wherein the liquid water uptake is 20% or less.
11 . The reinforced aerogel composition of claim 1 , further comprising an additive comprising silicon carbide.
12 . The reinforced aerogel composition of claim 1 , wherein the reinforcement material comprises polymer fibers.
13 . The reinforced aerogel composition of claim 12 , wherein the polymer fibers comprise polyacrylonitrile fibers, oxidized polyacrylonitrile fibers, or combinations thereof.
14 . The reinforced aerogel composition of claim 1 comprising a sheet that is 3 millimeter (mm) or less in thickness.
15 . The reinforced aerogel composition of claim 1 comprising a sheet that is from 1 mm to 3 mm in thickness.
16 . The reinforced aerogel composition of claim 1 comprising a sheet that is less than 1 mm in thickness.
17 . The reinforced aerogel composition of claim 1 , further comprising an opacifier additive.
18 . The reinforced aerogel composition of claim 1 , further characterized by a resilience of from 25% to 50% according to ASTM C1101.
19 . The reinforced aerogel composition of claim 1 , further characterized by a flexibility of from 5° to 65° according to ASTM C1101.