Some Remarks on the Degree of Crystallinity Measured on DSCOA

A modified mathematical model based on the melting and recrystallization of an initial distribution of melting temperatures predicts the melting behavior of polymer in differential scanning calorimetry ( DSC ), taking into account of changes in heat of fusion with melting temperature of crystal and average heat capacity of sample. It has been used to analytically prove that the crystallinity measured on a DSC diagram could not be equal to the weight percentage of crystalline state in the initial specimen. The deviation of the measured crystallinity, as observed relevant to the melting and recrystallization processes, is caused by the changes of the heat of fusion with the melting temperature of crystals, as well as the difference of heat capacities of liquld and solid state polymer. Furthermore, upper and lower limits of the deviation have been discussed.