THERMAL-CONDUCTIVITY OF THE NEMATIC LIQUID-CRYSTAL 4-N-PENTYL-4'-CYANOBIPHENYL

We report experimental results for the thermal conductivities of 4-n-p entyl-4'-cyanobiphenyl (5CB) for 19 degrees C<T <48 degrees C. For T<T -NI=35.17 degrees C this substance is a nematic liquid crystal, where T-NI is the nematic-isotropic transition temperature. The conductiviti es were determined by measuring the temperature difference across a ho rizontal layer of the fluid heated from below in magnetic fields eithe r parallel or perpendicular to the heat current. The field magnitude w as much larger than the Freedericksz field. For T<T-NI, this yielded m onodomain samples with the director oriented parallel to the field, an d thus the conductivities lambda(parallel to) and lambda(perpendicular to) with the director parallel and perpendicular to the heat current, respectively.