The lattice thermal conductivity of a semicrystalline polymer was studied at low temperatures by calculating the total lattice
thermal conductivities of four samples of polyethylene with different degrees of crystallinity between 0.43 and 0.81 and temperatures
between 0.4 and 20 K. The contributions of the crystalline and noncrystalline natures and their percentage contributions were
taken into account. The predicted lattice thermal conductivity of polyethylene was in fairly good quantitative agreement with
the experimental value, and showed a strong crystallinity dependence, with a distinctive cross-over point at about 2 K.