Departmental Bulletin Paper Synthesis and Thermal Properties of Epoxy Resins Cured with Lignin-related Biphenols Having Syringyl Structure

Hirose, Shigeo  ,  Sakamoto, Yusuke  ,  Sugamori, Yoshihiko

4,4’-Dihydroxy3,3’,5,5’-teramethoxybiphenyl(DHTMB) was synthesized from syringol, which can be obtained by thermal and hydration degradation of lignin. As the model reaction for curing, octaethylene glycol diglycidyl ether was cured with DHTMB and also with4,4’-dihydroxybiphenyl (DHB) in the presence of 2-ethyl-4-methylimidazole (2E4MI).Curing reaction was studied by differential scanning calorimetry (DSC). The calculated activation energies (E’s) were almost the same values for both curing systems. The mixture of epoxy compounds consisting of trimethylopropane triglycidyl ether and diethylene glycol diglycidyl ether was cured with DHTMB in the presence of 2E4MI. The above mixture of epoxy compounds was also cured with DHB. Thermal properties of cured epoxy resins were investigated by DSC. Glass transition temperature determined by DSC was 46.6℃ for that cured with DHTMB and 38.8℃ for that with DHB, suggesting that the existence of bulky methoxyl groups in syringyl structure restricts the main chain motion of cured epoxy resin.

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