An adhesive sealant composition of at least one moisture-crosslinkable prepolymer and an anti-sagging agent of 5% to 30% by weight of a thixotropic composition of 10% to 40% by weight of a bisurea a) obtained by reaction of a primary aliphatic amine a1) with a diisocyanate a2) having a molar mass of less than 500 g/mol, and 60% to 90% by weight of an ester b) of formula (I): ##STR00001##
in which R.sup.1, R.sup.2 and R.sup.3 are an oxycarbonylalkyl radical having from 4 to 20 carbon atoms, R.sup.4 is hydrogen, methyl or ethyl or —CH.sub.2—R.sup.5 in which R.sup.5 is oxycarbonylalkyl having from 4 to 20 carbon atoms, in the form of a suspension of solid particles of bisurea a) in a continuous phase formed by ester b).

Disclosed herein is a method of preparing a silica aerogel. The silica aerogel is prepared by adding a first water glass solution and an acid catalyst to a reactor to form a first silica wet gel. The method further includes adding a second water glass solution and an acid catalyst to the first silica wet gel. The method further includes adding a surface modifier solution to the first silica wet gel to form a second silica wet gel. The method further includes drying a silica wet gel including the first silica wet gel and the second silica wet gel. The prepared silica aerogel has a tap density of 0.032 to 0.070 g/mL and a carbon content of 11.2 to 12.1 wt %.

A thermothickening fluid is provided which comprises a liquid phase; a first polymer comprising functional groups and having a room temperature solubility in the liquid phase; and a second, different polymer comprising functional groups and having a room temperature solubility in the liquid phase, wherein functional groups on the first polymer are capable of associating with functional groups on the second polymer to form complexes, and the room temperature solubility of the first polymer is greater than the room temperature solubility of the second polymer. The fluid is a colloid at room temperature, a solution at an elevated temperature, and exhibits a thermothickening/thinning transition viscosity value at a thermo-thickening/thinning transition temperature between room temperature and the elevated temperature.

An improved design for an athletic helmet incorporating non-Newtonian fluid shock absorbing structures.

1) Thixotropic composition comprising: from 10% to 40% by weight of a bisurea a) obtained by reaction of a primary aliphatic amine a1) with a diisocyanate a2) having a molar mass of less than 500 g/mol, and from 60% to 90% by weight of an ester b) of formula (I):

##STR00001##

in which: R.sup.1, R.sup.2 and R.sup.3 represent an oxycarbonylalkyl radical having from 4 to 20 carbon atoms; R.sup.4 represents a hydrogen atom, a methyl or ethyl radical or else a radical: —CH.sub.2—R.sup.5 in which R.sup.5 represents an oxycarbonylalkyl radical having from 4 to 20 carbon atoms;

said composition being in the form of a suspension of solid particles of bisurea a) in a continuous phase formed by the ester b).

2) Adhesive sealant composition comprising at least one moisture-crosslinkable prepolymer and, as anti-sagging agent, from 5% to 30% by weight of said thixotropic composition.

A method for manufacturing an aerogel sheet according to the present invention includes: a step (a) of preparing a blanket having a plate shape; a step (b) of mixing silica sol with gelling catalyst to prepare a silica sol precursor; and a step (c) of injecting the silica sol precursor prepared in the step (b) to a surface of the blanket prepared in the step (a) through an injection device to gelate the silica sol precursor, wherein, in the step (c), the injection device injects the silica sol precursor while moving from one side to the other side of the surface of the blanket.

Provided is a silica aerogel with enhanced physical properties. The silica aerogel can have a tap density of 0.030 to 0.070 g/mL, and a carbon content of 11.2 to 12.1 wt %.

The present invention relates to a method for producing a silica aerogel and a silica aerogel produced thereby. More specifically, a first water glass solution is used to form a first silica wet gel, and then a second water glass solution is additionally added to form a second silica wet gel organically bonded to the first silica wet gel which serves as a basic skeleton, so that a silica aerogel with enhanced physical properties is formed to increase the resistance to shrinkage in ambient drying. Thus, a low-density silica aerogel may be formed, and the concentrations of the first and second water glass solutions may be adjusted to control the physical properties of the silica aerogel.

The present invention relates to a method for producing a silica aerogel and a silica aerogel produced thereby. More specifically, a first water glass solution is used to form a first silica wet gel, and then a second water glass solution is additionally added to form a second silica wet gel organically bonded to the first silica wet gel which serves as a basic skeleton, so that a silica aerogel with enhanced physical properties is formed to increase the resistance to shrinkage in ambient drying, and the concentration of silicon dioxide in each of the first and second water glass solutions is controlled, thereby providing a method for producing a silica aerogel by which a silica aerogel having a specific tap density and controllable density can be produced, and also providing a silicon aerogel produced by the method.

The present invention relates to a method for producing a silica aerogel and a silica aerogel produced thereby. More specifically, a first water glass solution is used to form a first silica wet gel, and then a second water glass solution is additionally added to form a second silica wet gel organically bonded to the first silica wet gel which serves as a basic skeleton, so that a silica aerogel with enhanced physical properties is formed to increase the resistance to shrinkage in ambient drying, and the concentration of silicon dioxide in each of the first and second water glass solutions is controlled, thereby providing a method for producing a silica aerogel by which a silica aerogel having a specific tap density and controllable density can be produced, and also providing a silicon aerogel produced by the method.