Precision differential calorimetry and the heat of fusion of polyethylene

Abstract A procedure is described for the analysis by computer of the output from a differential scanning calorimeter. Enthalpy calibration with a variety of materials confirms that alumina is excellent for this purpose. Both the crystallinity, x T , and the heat of fusion of polyethylene, ΔH T , vary with temperature and it is important that both are measured. The use of a room‐temperature crystallinity with a high‐temperature heat of fusion can be very misleading. Interfacial effects are shown to be negligible in most cases and the heat of fusion of perfectly crystalline polyethylene is given by ΔH T /x T . It is 309 Jg −1 at the melting point.