Abstract
The glass transition behavior of poly(diethylene glycol-co-succinic acid) (DEGSA) and its complexes obtained in the reaction with MgO have been investigated. The number average molar mass (\(\bar M_N \)) of the DEG-SA samples prior to complexation was determined by titration of the terminal COOH groups. The glass transition temperature (Tg) was measured as a function of molar mass and Mg2+ ion content. The dependence of Tg on\(\bar M_N \) obeyed the Fox-Flory relationship. Addition of increasing amounts of MgO to DEG-SA led to a gradual increase in Tg, and a decrease in the heat capacity change (Δcp). This behavior is associated with complex formation between COO-and Mg2+. The decrease in Δcp is a result of ion-ion and to a lesser extent ion-dipole interactions which lower chain mobility. The common limiting Tg value for the three DEG-SA samples at an Mg2+/COO- ratio of ca. 0.5 approaches Tg,∞, which is the corresponding Tg of a polymer of infinite molar mass.
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