| PET is widely used in many fields due to its excellent mechanical strength,thermostability,radiation resistance,optical clarity,barrier properties,and competitive performance-to-cost ratio.With the improvement of people's lives,the demand for PET is increasing day by day.Because PET is difficult to be degraded by microorganisms,PET waste products are accumulated year by year.In order to reduce the burden on the environment,in response to the call for recycling economy,this paper will recycle waste PET to make high value-added waterborne polyurethanes(WPU).PET was depolymerized by diethanolamine(DEA)in the presence of sodium aluminate as a catalyst.The effects of temperature,time,diethanolamine dosage,and sodium aluminate dosage on the glycolysis reaction were examined.The paper explored the effects of degradation time,temperature,the amount of diethanolamine and catalyst on the degradation yield of PET.The results show that the mass ratio of PET to diethanolamine is 1:4,and the catalyst NaAlO2 accounts for 1.6%of the total mass of PET.The reaction was carried out at 190? for 2 h.The degradation rate was 99.0%.The obtained liquid degradation mixture was separated and purified,and treated with acid and acetone respectively,and two degradation products TPA and BHAET were mainly obtained.TPA is a white solid powder that precipitates under acidic conditions and BHAET is a colorless,transparent crystal that recrystallizes in acetone.The yields of TPA and BHAET were 77.7%and 12.0%,respectively,and the total yield of the two products was 89.7%.The two products were characterized and analyzed by 1H NMR,13C NMR,XRD,FTIR,TG/DSC,and mass spectrometry.It was found that TPA is mainly terephthalic acid and BHAET is mainly bis(2-((2-hydroxyethyl)amino)ethyl)terephthalate.TPA and BHAET products were found to sublime through thermal analysis.The sublimation temperature of TPA was 374?,BHAET sublimed at 183?,and thermal decomposition occurred at 383?.Among them,TPA is an important raw material for organic synthesis,and BHAET is used for further modification to obtain other organic polymer materials.In this thesis,the study on the synthesis of waterborne polyurethanes using the degradation product BHAET was carried out.BHAET reacted with citric acid for 30 minutes at 140? and 100?,respectively.The structure of the reaction product was analyzed by using infrared analysis technology.Citric acid was esterified with BHAET to obtain CAB.CAB and butylenediamine and isophorone diisocyanate(IPDI)were used to synthesize waterborne polyurethane(WPU)in a two-step process.The effect of the ratio of BHAET and citric acid on the thermal stability of the reaction product WPU was analyzed.The best thermal performance was obtained when the molar ratio of BHAET to citric acid was 1:1.3.This article explored the performance differences of waterborne polyurethanes synthesized from different CAB.With the increase of citric acid content in CAB,the contact angle of WPU thus prepared decreases,viscosity increases,water absorption increases,solvent resistance increases,surface drying time becomes longer,particle size decreases,and particle size distribution range narrows.All synthetic waterborne polyurethanes have a storage stability of six months and good calcium ion stability. |
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