Provided is a flame retardant and heat insulating material having high flame retardancy and a high heat insulating property. Also provided is a flame retardant heat insulator including such flame retardant and heat insulating material having high flame retardancy and a high heat insulating property. A flame retardant and heat insulating material according to one embodiment is formed from a resin composition (A), wherein the resin composition (A) contains: a binder resin; a low-melting point inorganic substance; a high-melting point inorganic substance; and voids. A flame retardant and heat insulating material according to one embodiment is formed from a resin composition (B), wherein the resin composition (B) contains: a binder resin that produces a high-melting point inorganic substance when heated; a low-melting point inorganic substance; and voids and/or a void-forming agent.

Polysulfide compositions having a polyether synergist are disclosed. Polysulfide compositions that contain polyether synergists exhibit a rapid onset of cure and have acceptable final properties. The polysulfide compositions can be used as sealants.

Polysulfide compositions having a polyether synergist are disclosed. Polysulfide compositions that contain polyether synergists exhibit a rapid onset of cure and have acceptable final properties. The polysulfide compositions can be used as sealants.

A two-component polyurethane compositions including (i) a polyol component A comprising a tri- or higher functional polyol P1 having an OH equivalent weight of from 60 g/mol to 250 g/mol and a di- or tri-functional polyether or polyester polyol P2 which is different from the polyol P1; and (ii) an isocyanate component B comprising at least one polyisocyanate I. Polyurethane compositions have surprisingly been found to be suitable for 3D printing processing, where they provide printed 3D objects with reduced tackiness even shortly after the printing. In addition, the invention provides processes for the production of three dimension objects form such compositions as well as three dimensional objects prepared accordingly and the use of corresponding compositions in 3D printing processes.

A two-component polyurethane compositions including (i) a polyol component A comprising a tri- or higher functional polyol P1 having an OH equivalent weight of from 60 g/mol to 250 g/mol and a di- or tri-functional polyether or polyester polyol P2 which is different from the polyol P1; and (ii) an isocyanate component B comprising at least one polyisocyanate I. Polyurethane compositions have surprisingly been found to be suitable for 3D printing processing, where they provide printed 3D objects with reduced tackiness even shortly after the printing. In addition, the invention provides processes for the production of three dimension objects form such compositions as well as three dimensional objects prepared accordingly and the use of corresponding compositions in 3D printing processes.

Aerogels comprising a hydrophobic polyimide moiety, including hydrophobic polyimide aerogels, as well as methods of manufacture and applications thereof, are generally described.

##STR00001##

Aerogels comprising a hydrophobic polyimide moiety, including hydrophobic polyimide aerogels, as well as methods of manufacture and applications thereof, are generally described.

##STR00001##

Provided is a hollow particle, including silica, having a D.sub.SL of primary particles that satisfies the following expression (1), and having a breaking strength of 10 MPa or more: 1≤D.sub.SL≤1.5 . . . (1) where D.sub.SL=D.sub.75L/D.sub.25L, and D.sub.25L and D.sub.75L represent a 25th value and a 75th value, respectively, when long diameters of 100 randomly selected primary particles are measured in observation with a scanning electron microscope and sorted in order of increasing size.

Provided is a hollow particle, including silica, having a D.sub.SL of primary particles that satisfies the following expression (1), and having a breaking strength of 10 MPa or more: 1≤D.sub.SL≤1.5 . . . (1) where D.sub.SL=D.sub.75L/D.sub.25L, and D.sub.25L and D.sub.75L represent a 25th value and a 75th value, respectively, when long diameters of 100 randomly selected primary particles are measured in observation with a scanning electron microscope and sorted in order of increasing size.

Provided is a hollow particle, including silica, having a D.sub.SL of primary particles that satisfies the following expression (1), and having a breaking strength of 10 MPa or more: 1≤D.sub.SL≤1.5 . . . (1) where D.sub.SL=D.sub.75L/D.sub.25L, and D.sub.25L and D.sub.75L represent a 25th value and a 75th value, respectively, when long diameters of 100 randomly selected primary particles are measured in observation with a scanning electron microscope and sorted in order of increasing size.