Enzyme-catalyzed Preparation Of Dimeric Acid Polyester Polyol From Biodiesel And Its Further Synthesis Of Polyurethane

Biodiesel, one of the renewable and green energy sources, has gained more and moreattention. However, the high cost of biodiesel production and the only product——biodiesel, which is not a high-valued commodity, can not satisfy the purpose of corporateearnings. In order to improve the economic benefit and change the present situation of thesingle product structure in biodiesel industry, this study takes advantage of the structurecharacteristics of biodiesel to extend biodiesel industry chain by using it as a platformchemical. Based on the previous exploration in our laboratory, the thesis aims to study thetechnical feasibility and economic rationality of the biodiesel further processes——thesynthesis of dimeric acid polyester polyol (DAPP) and polyurethane. The main results aredescribed as follows:(1) Purification of dimeric acid methyl ester (DAME) by molecular distillation.Crude DAME was synthesized from Chinese tallow kernel oil biodiesel according toprevious studies of our laboratory. The crude DAME was then purified via moleculardistillation. The conditions for separation were optimized as: preheating temperature45°C,evaporating temperature110°C for primary distillation and160°C for secondarydistillation, agitating rate100r/min, vacuum degree2.010-2mbar, and feeding rate2mL/min. Under the optimal conditions, the final yield of DAME was48.8%. The finalproduct was further confirmed by Fourier transform infrared spectroscopy (FTIR) andNuclear magnetic resonance (NMR).(2) Enzymatic synthesis of DAPP. The synthetic process of DAPP was conductedthrough polymerization between DAME and ethylene glycol (EG) using Novozym435ascatalyst. Single factorial experiments and Response Surface Methodology (RSM) wererespectively conducted to examine the effects of different parameters on thepolymerization reaction. The best result was achieved under the optimal conditions:Novozym435loading2.9%(w/w), reaction temperature70°C, molar ratio of EG/DAME2.2:1.0, and reaction time9.7h. The final product was analyzed via FTIR and NMR. Thehydroxyl value of the obtained DAPP was87.47. In addition, the molecular weight and the acid value were2,000g/mol and0.56mg KOH/g, respectively.(3) Synthesis of polyurethane from DAPP. The TGA analysis of the syntheticpolyurethane showed good thermal stability. At the initial heating stage, no volatileconstituents escaped from the polyurethane. With the increase of temperature, thermaldecomposition of polyurethane was divided into two stages: the first stage,240–370°Cand the second,370–480°C. When temperature reached480°C, polyurethane wascompletely decomposed with no residue. DSC analysis showed good low temperatureperformance. Polyurethane gave low glass transition temperature, Tg=-52°C, and therewas only one peak in the result, which suggests the polyurethane is suitable for coatingindustry.(4) Finally, the economic benefits of biodiesel-based DAPP and polyurethane werepreliminarily analyzed. Taking a company producing50,000tons of biodiesel as anexample, the production process from the biodiesel to DAPP and polyurethane wereanalyzed in economic assessment. Results showed that polyurethane based on biodieselfurther process can greatly improve the biodiesel companies’ profit and the preparation ofpolyurethane was economic rationality.