(726c) Controlled Radical Polymerization of Lignin-Derived Bio-Oil for Melt-Spinnable Thermoplastic

Wangda Qu¹, Yuerui Huang², Eric Cochran², Xianglan Bai¹

¹ Department of Mechanical Engineering

² Department of Chemical and Biological Engineering

Lignin based polymers can be low-cost, green alternatives of petroleum-based polymers. In the present study, red oak lignin-derived bio-oil was used as the starting material to synthesize melt-spinnable thermoplastics. The lignin bio-oil was obtained by fast pyrolyzing red oak at 500 °C followed by water washing the crude bio-oil. The average Mw of the lignin bio-oil was 566 g/mol, and it consists of various phenolic monomers and oligomers. The NMR analysis indicated that there were three OH groups per unit in average. During the first-step of synthesis, the OH groups in the bio-oil was fully or partially methyacrylated. For the partly methyacrylated bio-oil, the remaining OH groups were either acetylated or left as is. In the following step, reversible addition fragmentation chain-transfer (RAFT) method was applied to polymerize the methyacrylated bio-oil. As a result, gelation was only observed with the fully methyacrylated bio-oil for thermosetting. Two other partially methyacrylated bio-oil with and without acetylation were successfully converted into thermoplastics. The Mw and polydispersity index of the polymer generated from the partially methylated bio-oil followed by acetylation were 16k g/mol and 1.53, respectively. The polymer also had a T_g of 130 ºC and T_d of 250 ºC, and the viscosity only increased from 376 and 878 Pa. s during isothermal rheology test at 210 ºC up to 10 min. The melt-spun fiber of this polymer was homogeneous in appearance and had a reduced brittleness compared to conventional lignin-based fibers. The yield of solid residue was 28% upon pyrolyzing to1000 ºC, implying that the fiber could be further developed into carbon fiber.