Tg displacements: Indicator of plasticization and antiplasticization effects on poly (ethylene terephtalate)

Abstract

In this work, the glass transition temperature, T g, is measured on a semi-crystalline polymer (poly(ethylene terephthalate) on which the moisture, r h, or the initial crystallinity, X c, change. It is observed that T g decreases when r h increases (increasing the plasticizer amount), while T g remains a constant when X c increases (increasing the antiplasticizer amount). Moreover, it is shown that the variations of T g with the heating rate follow an Arrhenius law. The activation energy, ( ΔE), depends on r h and on X c. The plasticization effect of water is revealed by a decrease of ΔE with the increase of r h while the crystallinity effect shows the opposite behaviour up to a crystallinity rate of 15%; above this value, the apparent activation energy remains constant.