| Compared to conventional monomeric plasticizers, polyester plasticizer has a highmolecular weight, which offers low volatility combined with outstanding resistance toextraction by oils and solvents, and displays excellent compatibility with polymer materials.Polyester plasticizer is one of the development tendencies of plasticizers.In this paper, poly(tetraethylene glycol adipate) was synthesized from adipic acid andtetraethylene glycol by esterification and polycondensation reaction. The effects of types andamounts of catalysts, temperature and time on the synthesis were investigated. The optimalreaction conditions were as follows: molar ratio of tetraethylene glycol to adipic acid is1:1,amount of catalyst is0.15%(based on the mass of acid and glycol), reaction time undernormal atmosphere is7h (temperature: from150℃to195℃), and reaction time undervaccum (-0.095MPa) is2.5h (temperature:195℃). Under these conditions, pale yellowpoly(tetraethylene glycol adipate) with appropriate viscosity could be obtained. The structureand properties of polyester was characterized by titration of acid value and hydroxyl value, FTIR,1H NMR, GPC and rheological properties.1H NMR measurements showed that theintegral area of relative hydrogen was different when the reaction degree and the molar ratioof tetraethylene glycol to adipic acid were different. GPC measurements displayed that thepolyester with high molecular weight and narrow distribution could be obtained by increasingreaction temperature and vaccum. Rheological measurements showed that the polyester waspure viscous material and its viscosity did not change with the frequency. The plasticization ofthe polyester produced was evaluated by adding the polyester into poly(lactic acid) and PVAcemulsion. The blend film was prepared by evaporating the CHCl3solution of poly(lactic acid)(PLA)and the polyester. The structure and properties of the film were measured by FT IR,mechanical properties, DSC, DMA, water absorption and extraction, ect. Mechanicalmeasurement results showed that the tensile decreased, and breaking elongation obviouslyincreased with increasing the content of the polyester in the film. DSC results displayed thatthe glass transition temperature, the melting point and cold crystallization temperature of PLAdecreased, while crystallinity slightly increased with the increase of polyester. DMAmeasurements showed that the film displayed an unimodal peak of Tg, the storage modulivalue decreased and tanδ shift to low temperature when the content of polyester increased inthe film. The introduction of the polyester could improve the hydrophiphility of the film, butthe resistance to extraction by solvents was excellent.Finally, PVAc blend emulsion with high solid content was prepared by adding thepolyester into PVAc emulsion. The storage stability at low temperature (5℃) and hightemperature (50℃) were observed. The results showed that the blend emulsion displayedexcellent low and high temperature storage stability, except that the polyester was separatedfrom the blend emulsion at50℃. Both PVAc emulsion and the blend emulsion displayed thethin-shearing behaviors, the viscosity of the blend emulsion increased at the same shearingrate when the polyester added increased. Dynamic temperature scanning results showed thatthe gelation temperature (Tgel) and the minimum of film forming temperature (MFT) of theblend emulsion decreased when the polyester was introduced into the PVAc emulsion.Structure and properties of the blend film was characterized by FT IR, DSC and TGA-DTG.The glass transition temperature of PVAc film deceased with the increase of polyester content,while the decomposition temperature and the amount of residual carbon increased. |
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