화학공학소재연구정보센터
Journal of Polymer Science Part B: Polymer Physics, Vol.37, No.7, 715-723, 1999
Thermal behavior of ferroelectric Polyamide 11 in relation to pyroelectric properties
The pyroelectric properties of oriented thin films of ferroelectric Polyamide 11 have been studied in the temperature range of -100 degrees C up to +140 degrees C. The temperature dependence of the experimental pyroelectric coefficient has been analyzed. Three changes of slope of the pyroelectric coefficient are observed at -20, +50, and +100 degrees C. The origin of the lower temperature event has not yet been defined. The upper transition is attributed to chain movements in crystalline regions, and more precisely, to a crystalline phase transition. The intermediate event is close to the glass transition temperature T-g observed by DSC. It is attributed to the manifestation of the glass transition. Below T-g, the variations of the pyroelectric coefficient are very small. For higher temperatures, it increases rapidly, attesting to a major contribution of secondary pyroelectricity and dimensional effects above T-g. The breaking of hydrogen bonds occurring at the glass transition temperature observed on DSC thermograms does not affect pyroelectric properties. Pyroelectric properties are mildly reduced after annealing at temperatures up to +140 degrees C. A comparative study of oriented ferroelectric films prepared by quenching from the melt and nonoriented slowly cooled samples has been carried out by means of DSC.