An epoxidized lignophenol (ELP) was synthesized by a two-step reaction from a lignophenol (LP) as the starting material. The reaction of LP with epichlorohydrin was carried out in the presence of a phase transfer catalyst, tetrabutylammonium bromide, at 90°C without alkaline reagent, followed by...
An epoxidized lignophenol (ELP) was synthesized by a two-step reaction from a lignophenol (LP) as the starting material. The reaction of LP with epichlorohydrin was carried out in the presence of a phase transfer catalyst, tetrabutylammonium bromide, at 90°C without alkaline reagent, followed by epoxidation with aq. NaOH solution. Epoxy groups in ELP were found to react with phenolic OH groups of coniferyl alcohol as a model compound of LP, which was used as a curing agent in this study. Direct curing of ELP with LP resulted in heterogeneous cured resins, and therefore, petrochemical epoxy resins of bisphenol A diglycidyl ether (DGEBA) and 3,4-epoxycyclohexylmethyl 3′,4′-epoxycyclohexanecarboxylate (ECEC) were used with ELP in order to improve the fluidity of the systems. Epoxy resins that mixed ELP with DGEBA or ECEC were cured with LP by heating up to 180°C in the presence of imidazole derivative (2E4MZ-CN); these afforded ELBL and ELCL as novel thermosetting resins. The ELBL and ELCL showed well-balanced thermal and mechanical properties. Especially, the glass transition temperature (Tg) of the ELCL(70) , which included 30 wt% of ECEC as the epoxy resin where the total amount of LP element was 82 wt%, was 219°C. This value was 85°C higher than that of the conventional phenol novolac-cured DGEBA. These results demonstrated that LP was a promising biomass material for thermosetting resins.
An epoxidized lignophenol (ELP) was synthesized by a two-step reaction from a lignophenol (LP) as the starting material. The reaction of LP with epichlorohydrin was carried out in the presence of a phase transfer catalyst, tetrabutylammonium bromide, at 90°C without alkaline reagent, followed by epoxidation with aq. NaOH solution. Epoxy groups in ELP were found to react with phenolic OH groups of coniferyl alcohol as a model compound of LP, which was used as a curing agent in this study. Direct curing of ELP with LP resulted in heterogeneous cured resins, and therefore, petrochemical epoxy resins of bisphenol A diglycidyl ether (DGEBA) and 3,4-epoxycyclohexylmethyl 3′,4′-epoxycyclohexanecarboxylate (ECEC) were used with ELP in order to improve the fluidity of the systems. Epoxy resins that mixed ELP with DGEBA or ECEC were cured with LP by heating up to 180°C in the presence of imidazole derivative (2E4MZ-CN); these afforded ELBL and ELCL as novel thermosetting resins. The ELBL and ELCL showed well-balanced thermal and mechanical properties. Especially, the glass transition temperature (Tg) of the ELCL(70) , which included 30 wt% of ECEC as the epoxy resin where the total amount of LP element was 82 wt%, was 219°C. This value was 85°C higher than that of the conventional phenol novolac-cured DGEBA. These results demonstrated that LP was a promising biomass material for thermosetting resins.
Asada, Chikako, Nakamura, Yoshitoshi, Kobayashi, Fumihisa.
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Sun, Gang, Sun, Hongguang, Liu, Yu, Zhao, Binyuan, Zhu, Na, Hu, Keao.
Comparative study on the curing kinetics and mechanism of a lignin-based-epoxy/anhydride resin system.
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