Les effets thermiques associés à la transition vetreuse de films de poly(téearéphatalate d'éthylène)

Differential scanning calorimetry and thermomechanical analysis are used for examining the thermal behaviour of amorphous poly(ethylene terephthalate) films in the glass‐transition range. By variation of the heating rate between 0,2 and 100 K. · min−1, it is possible to obtain either an exotherm associated with a shrinkage, or an endotherm, or both of these phenomena. It is found that very low heating rates not only give rise to a retardation mechanism but also to a molecular rearrangement.