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CPP: Chemische Physik und Polymerphysik

CPP 19: Poster: New Methods, Thin Polymer Films, Monolayers

CPP 19.6: Poster

Donnerstag, 5. April 2001, 12:30–15:00, AT1

Thermal conductivity measurements by DSC — •Mikhail Merzliakov and Christoph Schick — Universitaet Rostock, Universitaetsplatz 3, 18051 Rostock

We present a method to determine simultaneously thermal conductivity and heat capacity of low thermal conducting materials like polymers. No additional measurements, no thermal conducting calibrants, no modifications of the commercially available DSC are necessary. The method is based on temperature waves propagation through the sample. At low frequencies of perturbation temperature waves go through whole sample without damping, all sample is modulated and therefore large effective heat capacity is measured. At higher frequencies temperature waves are damped and sample is modulated only partly. Thus measured effective heat capacity is smaller. The damping is stronger for poor thermal conducting materials. Marcus and Blaine [1] calculate thermal conductivity by temperature modulated DSC assuming that No-dqthe face of the specimen at the heat source follows the applied temperature modulationNo-dq. This is a serious and not always valid simplification which finally can yield high uncertainties for the obtained thermal conductivity data. We consider the whole thermal path from the heater to the sample surface. For measurements one can use periodic multi frequency perturbations as well as non-periodic step functions. The results of thermal conductivity for four polymers are compared with accepted values. [1] S. M. Marcus and R. L. Blaine, Thermochim. Acta 243 (1994) 231.