Mechanical and dielectric relaxations of epoxide resins containing the spiro‐ring structure. II. Effect of the introduction of methoxy branches on low‐temperature relaxations of epoxide resins

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AbstractMechanisms 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.