Improved utilization of crude glycerol from biodiesel industries: Synthesis and characterization of sustainable biobased polyesters

The present work describes the synthesis of biobased polyesters using glycerol of different purities and sources with the aim of understanding how glycerol composition can influence the resulting structure and properties of biobased polyesters. Glycerol and succinic acid based polyesters were synthesized using crude and technical grade glycerol obtained from biodiesel producing facilities. It was shown that the presence of impurities in crude glycerol can greatly decrease the yield of reaction and also lead to products with different chemical structure and composition than those derived from pure glycerol. In particular, the presence of fatty acids and soaps was shown to produce incorporation of fatty acid residues and formation of carboxylate residues in the polymer backbone respectively. The products synthesized from industrial technical grade glycerol with 95 wt% purity were similar to those formulated from pure glycerol, showing rubbery behavior at room conditions. The materials synthesized from crude glycerol showed different thermal and chemical properties due to incorporation of impurities from the glycerol source to the polymer backbone. It was concluded that technical glycerol could be used as an alternative to pure glycerol on the synthesis of polyesters without inducing major changes on the synthesis products.