| 초록 |
The glass-transition temperature (Tg) and degree of crystallinity (Xc) are important properties of polymers. However, for some newly synthesized polymers and expensive biopolymers, due to their limited quantity, 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. |
