| Abstract: | Mechanisms for low-temperature relaxations of three spiro-ring-type epoxide resin systems with and without methoxy branches were investigated by comparison with those of a bisphenol A-type resin system. In the spiro-ring-type epoxide resin systems, two well-defined relaxation peaks, denoted as the β and β′ relaxations, and a shoulder peak were observed at about ?70, +60, and 0°C, respectively. The magnitude of the β relaxation was decreased by the introduction of methoxy branches on the phenylene group. This phenomenon could be interpreted as a result of the formation of hydrogen bonds between the hydroxy-ether group and methoxy branch. Moreover, it was concluded that the β′ relaxation and the shoulder peak are due to the motion of the p-phenylene group adjacent to the spiro-ring and of the hydroxy-ether group blocked by the hydrogen bond, respectively. |
