Capacitive scanning dilatometry and frequency-dependent thermal expansion of polymer films

The dilatometric properties of polymer films near and above their glass-tra nsition temperatures were explored using capacitive high-frequency detectio n in temperature ramping as well as in harmonic temperature cycling experim ents. The broad applicability of capacitive scanning dilatometry is demonst rated by the investigation of macromolecular systems of vastly different po larity such as polystyrene, polybutadiene, and polyvinylacetate. From tempe rature cycling experiments the real and imaginary parts of the frequency-de pendent thermal-expansion coefficient are determined in the sub-Hz regime.