Low-dielectric and low-thermalconductivity aerogel composites and preparation method thereof

A method for preparing a low-dielectric and low-thermal conductivity aerogel/fiber composites, comprising:

• a mixed hydrolysis step:
• respectively mixing a siloxane compound, a methylsiloxane compound or a combination thereof with a large amount of an aqueous solution containing a trace amount of alcohols to form a mixed solution, and adding a catalyst containing a trace amount of acid under stirring to make the mixed solution undergo a hydrolysis reaction;
• a suspension dispersion condensation solution step:
• respectively adding a large amount of a dispersion aqueous solution containing alcohols and a trace amount of alkali catalyst aqueous solution in the mixed solution, and using a stirring device comprising an emulsifier or a homogenizer to rapidly suspend and disperse the mixed solution into a suspension and dispersion hydrolyzed siloxane/methylsiloxane compounds droplet in water system and perform a condensation reaction in the hydrolyzed siloxane/methylsiloxane compounds droplet to make the siloxane compound and the methylsiloxane compound condense to form a suspension dispersion condensation solution when the hydrolysis of the mixed solution of the hydrolyzed siloxane compound and the methylsiloxane compound is completed;
• a composite molding step:
• performing a pressure suction impregnation technology for the suspension dispersion condensation solution under vacuum conditions so as to promote the suspension dispersion condensation solution rapidly sucked into a fibrous substrate so that the condensation and aggregation of the hydrolyzed siloxane compounds and hydrophobic siloxane molecules are carried out in the fibrous substrate to form nano- sized to sub-micron-sized aerogel wet gel aggregates, which are then aggregated with each other in the fibrous substrate to form a three-dimensional network gel microstructure so as to form a wet aerogel/fiber composite material;
• and
• a drying and solvent recovery step:
• placing the wet aerogel/fiber composite material in a drying equipment with temperature range from 70° C. to 115° C. so that a large amount of the aqueous solution containing alcohols in the wet aerogel system is azeotropically evaporated so as to make the aqueous solution containing alcohols be quickly distilled out and recycled in a high temperature environment, and then placing the aerogel/fiber composite material in the higher temperature range from 120° C. to 150° C. so as to form a dried aerogel/fiber composites by rapid evaporation.