MECHANICAL AND DIELECTRIC RELAXATIONS OF EPOXIDE-RESINS CONTAINING THE SPIRO-RING STRUCTURE .2. EFFECT OF THE INTRODUCTION OF METHOXY BRANCHES ON LOW-TEMPERATURE RELAXATIONS OF EPOXIDE-RESINS

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 beta and beta prime relaxations, and a shoulder peak were observed at about minus 70, plus 60, and 0 degree C, respectively. The magnitude of the beta relaxation was decreased by the introduction of methoxy branches of hydrogen bonds between the hydroxy-ether group and methoxy branch. Moreover, it was concluded that the beta prime 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.