Thermal conductivity of linear and network polyesters

We report a range of nearly one order of magnitude, 0.09 ± 0.01 to 0.71 ± 0.1 W/(m K), of thermal conductivities that can be obtained by varying the molecular structure and morphology of polyesters formed from condensation reactions. We characterized the samples by X-ray scattering, scanning calorimetry, and vibrational spectroscopy, measured the thermal conductivities by time-domain thermoreflectance (TDTR) and displacement thermo-optic phase spectroscopy (D-TOPS). Polyesters with aromatic diol components, e.g., linear 2,6-dihydroxynaphthalene (L-dhn), exhibit enhanced thermal conductivity, approximately 2 times greater, and network polyesters with cyclic aliphatic components, such as 4,8-bis (hydroxymethyl)tricyclo [5.2.1.02,6]decane (N-tcddm), show low thermal conductivity, 2 times smaller than the thermal conductivity of polyethylene terephthalate (PET). We also report the anisotropy of the thermal conductivity of biaxially oriented PET and polyethylene naphthalate (PEN) films in the in-plane directions compared to the cross-plane direction. The overall trend in the thermal conductivity ( Λ ) as a function of mass density ( ρ ) is remarkably steep: Λ ∝ ρ 6 .