The density fluctuation model is used to analyze the lattice thermal conductivity data of two samples of polycarbonate between
0.04 and 1K. The study is carried out by calculating the latice thermal conductivity of a noncrystalline polymer as the sum
of two contributions asK=KBM+KEm, whereKBE is attributed to phonons which interact with the crystal boundaries,KEM is due to phonons which interact with the empty spaces. The relative importance of each contribution has also been examined
by estimating their percentage contributions to the lattice thermal conductivity. An excellent fit to the experimental data
was obtained over the whole temperature range.