On preparation, structure and performance of high porosity bulk cellulose aerogel

A novel approach has been applied in preparing cellulose aerogel foams by combining NaOH/thiourea/H2O solvent system and the freeze drying technology. The improvement involved adding 60 degrees C ethanol during the formation process of cellulose hydrogel. The effects of the solvent system on the structure and heat insulation performance of aerogel were studied. The gelation time reduced 63% and the mechanical strength of hydrogel reinforced 2.3% with 60 degrees C ethanol. The optimal ratio of the solvent system for cellulose was NaOH 9.5 wt-%, thiourea 4.5 wt-%. Under this condition, the obtained cellulose aerogel have a density range between 0.2 to 0.4 g cm(-3), and the porosity up to 84.88%. Cellulose aerogel had good heat insulation performance with the lowest thermal conductivity only 0.029 W m K-1. This work provided an effective preparation method for high porosity bulk cellulose aerogel, and showed the application potential of cellulose aerogel as insulation materials in the medium low thermal insulation field.