Synthesis and characterization of polyester polyols
Polyester polyols were prepared through esterification and polycondensation reactions using azelaic acid,adipic acid,and 1,4-butanediol as raw materials to investigate the effects of different dibasic acids on the properties of polyester polyols.The structures of the synthesized products were characterized by infrared spectroscopy,hydrogen NMR spectroscopy,gel chromatography,thermogravimetric analysis,and rotational rheology.The effects of the mole ratio of alcohol to acid and synthesis process on the acid and hydroxyl values of the synthesized product were studied.The acid and hydroxyl values of polyester polyols prepared under different reaction conditions were determined to obtain the optimal process conditions by adjusting parameters including reaction temperature and duration.The performance of the final products was tested after dealcoholization under reduced pressure.The results showed that the acid values of azelaic acid polyester polyols and adipic acid polyester polyols were 0.520 mg KOH/g and 0.830 mg KOH/g respectively.Their respective hydroxyl values were 39.0 mg KOH/g and 46.6 mg KOH/g;molecular weights were 19,421 and 19,219;and the temperatures for complete decomposition were 514 ℃ and 438 ℃.These findings suggest that azelaic acid polyester polyols have lower acid and hydroxyl values,better thermal stability,and lower viscosity than adipic acid polyester polyols.Therefore,azelaic acid is more suitable for the synthesis of polyester polyols than adipic acid.
polyester polyolesterification and polycondensationazelaic acidadipic acidsynthesis technology
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