The dependence on the thermal history of the dynamical and structural properties of a polymer liquid crystal has been evidenced by differential scanning calorimetry, infrared dichroism and non-linear electron spin resonance (ESR) spectroscopy in a wide range of temperatures. The behaviour of the microscopic viscosity as a function of both the isothermal annealing and the temperature is studied and its salient features are interpreted in terms of cooperativity. The multiexponential decay of the orientation correlation functions, relevant in the relaxation processes of linear and non-linear ESR spectroscopies, occurs in the supercooled and glassy phases, whereas the single exponential decay recovers above the isotropization temperature.
MICROSCOPIC TRANSPORT-PROPERTIES IN LIQUID-CRYSTALLINE POLYMERIC MATRICES - DEPENDENCE ON THE THERMAL HISTORY
ANDREOZZI, LAURA;GIORDANO, MARCO;LEPORINI, DINO;
1994-01-01
Abstract
The dependence on the thermal history of the dynamical and structural properties of a polymer liquid crystal has been evidenced by differential scanning calorimetry, infrared dichroism and non-linear electron spin resonance (ESR) spectroscopy in a wide range of temperatures. The behaviour of the microscopic viscosity as a function of both the isothermal annealing and the temperature is studied and its salient features are interpreted in terms of cooperativity. The multiexponential decay of the orientation correlation functions, relevant in the relaxation processes of linear and non-linear ESR spectroscopies, occurs in the supercooled and glassy phases, whereas the single exponential decay recovers above the isotropization temperature.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
