AbstractExtrapolation from data on low molecular weight n‐alkanes indicates that the surface tension of polyethylene at 150°C is 26 dynes/cm. The total surface energy, γ — Tdγ/dT, is 51 dynes/cm and is much less dependent on chain length. The surface tension of polyethylene extrapolated to 20°C is 34 dynes/cm, consistent with the critical surface tension below which liquids will wet the polymer. The total surface energy is in reasonable accord with the incremental energy of vaporization, 1.029 kcal/mole of CH2groups. The surface entropy is less than that of low molecular substances. This is attributed to a reduction in the opportunities for rotational isomerism at the