Glass transition temperatures as a function of composition in binary systems: Poly(ethylene oxide) + epoxy system

The glass transition temperatures (T$_{g})$ of PEO + epoxy resin blends in the full concentration range were analyzed. They were obtained by differential scanning calorimetry (DSC) and thermally stimulated current (TSC) depolarization. We have focused on the deviation from a linear relationship defined as $\Delta $T$_{g }$= T$_{g }$-X$_{A}$T$_{g,A}$ -X$_{B}$T$_{g,B }$, where T$_{g}$ is the glass transition temperature of the blend, X$_{i}$ is the weight fraction of $i$ component in the blend, while T$_{g, i}$ is the glass transition temperature of the $i$ component. A new equation for the Tg as a function of concentration was developed, based on an analysis of $\Delta $T$_{g}$. The results predicted with the new equation are better than those from the earlier T$_{g}$ equations, such as the Kwei equation, the Gordon-Taylor equation, and the Fox equation.