Abstract
Most commercial epoxy resins have been produced using toxic bisphenol A. Lignin can be utilized as green substitute for bisphenol A to produce bio-epoxy resins. Methanol-soluble kraft lignin was extracted by methanol fractionation for lignin epoxidation, and epoxidized into lignin-derived epoxy resin via two-step epoxidation consisting of epichlorohydrin addition and epoxide ring restructuring. Epoxidized lignin was selectively separated from non- or less-reacted lignin based on their solubility differences in organic solvents. The existence of epoxide groups in the lignin-derived epoxy resin was confirmed using FT-IR, 1H-NMR, and TGA analyses. Epoxidized lignin was used as a reactive lignin macromonomer to prepare biopolyester. The characteristics of the synthesized biopolyester were analyzed using FT-IR, and the thermal properties were analyzed by TGA. The thermal decomposition temperature of 5% weight loss (Td5) was determined to be 257.1°C, which is comparable to epoxy resins that are used in electronic applications.
ACKNOWLEDGMENTS
The authors would like to acknowledge the support by the R&D Program of the Ministry of Trade, Industry & Energy (MOTIE)/Korea Evaluation Institute of Industrial Technology (KEIT) (Project # 10049675) and the C1 Gas Refinery Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2015M3D3A1A01064882).
SUPPLEMENTAL MATERIAL
Supplemental data for this article can be accessed on the publisher's website at https://doi.org/10.1080/02773813.2017.1310901.