This document specifies a method for the determination of the thermal conductivity and thermal
diffusivity, and hence the specific heat capacity per unit volume of plastics. The experimental
arrangement can be designed to match different specimen sizes. Measurements can be made in gaseous
and vacuum environments at a range of temperatures and pressures.
This method gives guidelines for testing homogeneous and isotropic materials, as well as anisotropic
materials with a uniaxial structure. The homogeneity of the material extends throughout the specimen
and no thermal barriers (except those next to the probe) are present within a range defined by the
probing depth(s) (see 3.1).
The method is suitable for materials having values of thermal conductivity, λ, in the approximate
range 0,010 W∙m−1∙K−1 < λ < 500 W∙m−1∙K−1, values of thermal diffusivity, α, in the range
5 × 10−8 m2∙s−1 < α < 10−4 m2∙s−1, and for temperatures, T, in the approximate range 50 K < T < 1 000 K.
NOTE 1 The specific heat capacity per unit volume, C, C = ρ ∙ cp, where ρ is the density and cp is the specific heat
per unit mass and at constant pressure, can be obtained by dividing the thermal conductivity, λ, by the thermal
diffusivity, α, i.e. C = λ/α, and is in the approximate range 0,005 MJ∙m−3∙K−1 < C < 5 MJ∙m−3∙K−1. It is also referred to
as the volumetric heat capacity.
NOTE 2 If the intention is to determine the thermal resistance or the apparent thermal conductivity in the
through-thickness direction of an inhomogeneous product (for instance a fabricated panel) or an inhomogeneous
slab of a material, reference is made to ISO 8301, ISO 8302 and ISO 472.
The thermal-transport properties of liquids can also be determined, provided care is taken to minimize
thermal convection.