Compatibility, mechanical and thermal properties of GAP/P(EO-co-THF) blends obtained upon a urethane-curing reaction

A series of cross-linked glycidyl azide polymer with poly(ethylene oxide-co-tetrahydrofuran) (GAP/P(EO-co-THF)) blends were prepared by varying the relative weight ratios of GAP to P(EO-co-THF) using poly-isocyanate mixed curing system (N100/TDI), and by varying the [NCO]/[OH] ratios to find the effects of curing agents on mechanical properties. The compatibility, thermal features and morphological studies of GAP/P(EO-co-THF) polymer networks were described by equilibrium phase diagram, differential scanning calorimeters (DSC) together with thermogravimetric analysis (TGA), scanning electron microscopy (SEM), respectively. The equilibrium phase figure of the partial miscibility system for GAP/P(EO-co-THF) shows that the system has a lower critical solution temperature (LCST). In addition, the DSC and TGA results indicate that the content of two components is gradually approaching, and the glass transition temperatures of GAP/P(EO-co-THF) blends are less than those of the pure GAP and P(EO-co-THF) polymers, and the initial decomposition temperature and the maximum decomposition rate temperature have greatly increased. Furthermore, the thermal decomposition behavior indicates that the thermal stabilities are improved and the physical entangled networks are strengthened. Moreover, the scanning electron microscopy (SEM) images show the GAP/P(EO-co-THF) blends form a certain polymer alloy structure, which is the reason for the improved thermal stabilities and the strengthened networks.