title: Study on Thermal Conductivities of Aromatic Polyimide Aerogels.
abstract: Polyimide aerogels for low density thermal insulation materials were produced by 4,4'-diaminodiphenyl ether and 3,3',4,4'-biphenyltetracarboxylic dianhydride, cross-linked with 1,3,5-triaminophenoxybenzene. The densities of obtained polyimide aerogels are between 0.081 and 0.141 g cm(-3), and the specific surface areas are between 288 and 322 m(2) g(-1). The thermal conductivities were measured by a Hot Disk thermal constant analyzer. The value of the measured thermal conductivity under carbon dioxide atmosphere is lower than that under nitrogen atmosphere. Under pressure of 5 Pa at -130 °C, the thermal conductivity is the lowest, which is 8.42 mW (m K)(-1). The polyimide aerogels have lower conductivity [30.80 mW (m K)(-1)], compared to the value for other organic foams (polyurethane foam, phenolic foam, and polystyrene foam) with similar apparent densities under ambient pressure at 25 °C. The results indicate that polyimide aerogel is an ideal insulation material for aerospace and other applications.
authors.affiliation: Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, National University of Defense Technology , 109 De Ya Road, Changsha, Hunan 410073, China.
authors.forename: Junzong
authors.initials: J
authors.lastname: Feng
authors.affiliation: Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, National University of Defense Technology , 109 De Ya Road, Changsha, Hunan 410073, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, National University of Defense Technology , 109 De Ya Road, Changsha, Hunan 410073, China.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, National University of Defense Technology , 109 De Ya Road, Changsha, Hunan 410073, China.
authors.forename: Dongxuan
authors.initials: D
authors.lastname: Du
authors.affiliation: Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, National University of Defense Technology , 109 De Ya Road, Changsha, Hunan 410073, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Feng
keywords: cross-link; low temperature; polyimide aerogels; supercritical drying; thermal conductivity