聚2,5-呋喃二甲酸乙二醇酯的合成与表征

以2,5-呋喃二甲酸和乙二醇为原料,草酸亚锡为催化剂,通过直接酯化法合成了线性高分子量聚2,5-呋喃二甲酸乙二醇酯(PEF).运用红外光谱(FTIR)和核磁共振氢谱(1H-NMR)表征了该聚酯的结构;由乌氏黏度计法和凝胶渗透色谱(GPC)建立了该聚酯在一种混合溶剂体系中特性黏数和重均分子量的关系:η]=2.82×10-6Mw0.99dL/g,25℃,苯酚-四氯乙烷(1∶1,W/W);示差扫描量热法(DSC)和热失重分析(TGA)测定了该聚酯的热转变性能,结果表明该聚酯玻璃化转变温度为84℃,熔点为211℃,起始热分解温度高于370℃,具有良好的热稳定性;运用旋转流变仪研究了PEF的流变性能,结果表明,PEF熔体属于假塑性流体,随相对分子量的减小和温度升高,其非牛顿指数增大,在高于PEF熔点20～40℃,剪切速率为2.17×10-2～1.14×102s-1时,PEF的非牛顿指数为0.85左右.

SYNTHESIS AND CHARACTERATION OF POLY(ETHYLENE 2,5-FURANDICARBOXYLATE)

Poly(ethylene 2,5-furandicarboxylate)(PEF) was synthesized via direct esterification method based on 2,5-furanicarboxylica acid and ethylene glycol.Stannous oxalate was used as catalyst.The results showed that the direct esterification method was a straightforward and convenient effective way for preparing PEF.The results of Fourier transform infrared spectroscopy(FTIR) and nuclear magnetic resonance spectroscopy(1H-NMR) confirmed the expected PEF structure.The results of Ubbelohde viscosity method and gel permeation chromatography(GPC) declared the relationship between intrinsic viscosities and weight-average molecular weight was η]=2.82×10-6 Mw0.99 dL/g,25℃,phenol-tetrachloroethane(1∶1,W/W)];The results of differential scanning calorimeter(DSC) displayed that the glass transition(Tg) of PEF was 84℃ which was 16 K higher than that of poly(ethylene terephthalate)(PET) and the melting temperature(Tm) of PEF was 211℃ which was 43 K lower than that of PET.The results of thermogravimetric analysis(TGA) showed that the PEF was thermally stable up to 373℃.PEF had good thermal properties and was similar to that of PET.The results of coaxial cylinder viscometer showed that the PEF melt was a pseudoplastic Newtonian fluid and its Non-Newtonian index increased with decreasing of relative molecular weight and increasing of temperature.Non-Newtonian index was about 0.85(melting temperature=230~250℃,rate of shear=2.17×10-2~1.14×102 s-1).