Detection of polymer transitions by measurement of thermal properties



Thermal diffusivity, thermal conductivity, and specific heat per unit volume were measured for the following polymers: poly(ethylene terephthalate), polytetrafluoroethylene, polycarbonate, polypropylene, and three poly(vinyl chloride) samples plasticized to different levels. First- and second-order transitions can be identified and located by the following features in the thermal property-temperature curves: discontinuities, sharp inflections, broad inflections, sharp maxima, broad maxima, and change in linear slope. The results for poly(vinyl chloride) indicate the possibility of the use of plasticizer to control the thermal insulation properties of polymers, both for steady-state and unsteady-state conduction.