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Efficient processing of bioglycerol to a novel biobased polyunsaturated monomer

Gómez, Claudia L, Echeverri, David A, Inciarte, Helen C, Rios, Luis A
Journal of chemical technology and biotechnology 2019 v.94 no.2 pp. 634-640
acid value, alkyd resins, biodiesel, chemical bonding, esterification, fuel production, glycerol, hardness, modulus of rupture, polyesters, potassium hydroxide, solvents, temperature
BACKGROUND: Commercial synthesis of polyunsaturated monomers, like polyester resins, involves an energy‐demanding esterification process, which is usually carried out at 150–220 °C and long reaction times (>12 h). In addition, most of these monomers come from petrochemical sources and, therefore, are not renewable. In this research, a new polyunsaturated monomer was synthesized using crude glycerol from biodiesel production (bioglycerol), through an alternative and efficient process. RESULTS: Bioglycerol was transformed to a polyunsaturated resin through maleinization and methacrylation reactions, under mild conditions (<100 °C and 2 h). The effects of temperature and molar ratio of reactants on these reactions were evaluated through a factorial design. The so‐obtained monomer was highly functionalized (5.05 double bonds per molecule) and negligible acid value (<2 mg KOH g⁻¹). To assess its reactivity, the monomer was copolymerized with methyl methacrylate (MMA), affording a rigid material with excellent mechanical properties. In general, the properties were better than those obtained for commercial unsaturated polyester thermosets (flexural modulus, 3783.4 MPa; flexural strength, 161.5 MPa; surface hardness, 76 (Shore D) and Tg, 100.9 °C). This new monomer could also be suitable for the production of other polymers such as alkyd resins. CONCLUSION: A new route to polyunsaturated monomers was developed from bioglycerol at relatively low temperatures, without solvents and with minimum intermediate purification stages. The monomer was suitable for reacting with MMA, affording a material with mechanical properties resembling those of a commercial unsaturated polyester thermoset. © 2018 Society of Chemical Industry