The glass-transition temperature (Tg) and degree of crystallinity (Xc) are important properties of polymers. However, for some polymers, current techniques have some difficulties in measuring Tg and Xc, particularly for as-prepared films without damage. Here, we develop a new technique to simultaneously determine Tg and Xc by measuring the restitution of a ball on an intact polymer film or sheet as a function of temperature. Demonstrating with eight different types of polymers, we show that Tg is the onset of the decrease in restitution, and Xc is the minimum restitution for semi-crystalline polymers with Xc up to 50%. Our simple yet versatile technique could provide a useful tool to measure challenging Tg and Xc of films and sheets by the conventional methods.
Herein, a study on a new lower critical solution temperature (LCST) polymer in an organic solvent by an electrochemical technique has been reported. The phase-transition behavior of poly(arylene ether sulfone) (PAES) was examined on 1,2-dimethoxyethane (DME). At a temperature above the LCST point, polymer molecules aggregated to create polymer droplets. These droplets subsequently collided with an ultramicroelectrode (UME), resulting in a new form of staircase current decrease. The experimental collision frequency and collision signal were analyzed in relation to the concentration of the polymer. In addition, the degree of polymer aggregation associated with temperature change was also observed.
