Thermal resistivity and conductivity
Thermal resistance is the ability of a material to resist flow of heat. Thermal resistivity is the reciprocal of thermal conductivity and can be expressed as
r = 1 / k (1)
r = thermal resistivity (moC/W, hr ft2 oF/(Btu in))
k = thermal conductivity (W/(moC), Btu in/(hr ft2 oF))
Thermal conductivity - k - is the property of a material indicating its ability to conduct heat.