Comparison of head‐to‐head and head‐to‐tail polystyrenes by thermally stimulated discharge

Thermally stimulated depolarization (TSD) experiments were carried out on several polystyrene samples. They included normal head‐to‐tail polystyrene (atactic) obtained by anionic polymerization of styrene, amorphous and substantially crystalline isotactic polystyrene, and the newly available head‐to‐head polystyrene. By TSD, six maxima of current intensity occurred at specific temperatures. Their features are compared for the various samples. Only three peaks could be identified with transitions which had been found by other techniques. Peak 5, located near Tg, is the primary relaxation. Maximum 6 could be the transition found above the Tg by torsional braid analysis and called T11 for polystyrene samples. Maximum 1 seems to correspond to what is sometimes referred to as the γ transition.