Thermal conductivities of cellulose diacetate based aerogels

Cellulose diacetate (CDA) based aerogels for thermal insulation were prepared by CDA cross-linked with 2, 4-toluene diisocyanate (TDI) in acetone solvent. The relationship between structure and thermal conductivity of CDA-based aerogels with various reactant ratios (CDA/TDI) was studied. The obtained results show that the increase of reactants causes higher bulk density and smaller porosity of as-prepared aerogels, while its specific surface area decreases with CDA content increasing. Thermal conductivity increases with CDA content increasing, and the minimal value is 0.0313 W m(-1) K-1 comparably to that of polyimide aerogel at the same environmental conditions. Meanwhile, the radiant thermal conductivities of CDA-based aerogels were calculated in the range of 0.0021-0.0054 W m(-1) K-1 superior to other cellulose aerogels using wafer method. Moreover, the analyses for thermal conductivity distributions of above aerogels suggest that the solid thermal conductivity proportion increases with reactant content increasing, the gaseous one falls down, and the radiant one changes hardly.