Glass transition cooperativity from heat capacity spectroscopy — temperature dependence and experimental uncertainties

The influence of experimental uncertainties of calorimetric parameters from heat capacity spectroscopy on the temperature-dependent glass transition cooperativity Nα from the fluctuation approach is studied. Glass transition parameters from 3ω method and temperature modulated DSC are compared. The influence of the stationary temperature field on the output of the 3ω method is studied. Special advantages and disadvantages of 3ω method and temperature modulated DSC for the determination of glass transition cooperativity are discussed. It is confirmed that the temperature-dependent cooperativity indicates, independent from experimental uncertainties, a cooperativity onset in the crossover region. The extrapolated onset temperature Ton from calorimetry is shown to be comparable with other, independently obtained crossover temperatures for polystyrene and styrene butadiene rubber (SBR 1500).