The Study On Copolyesters Of Poly(ethylene Terephthalate)-block-poly(ethylene Furandicarboxylate)

Nowadays, expensive non-renewable resource is the lifeblood of the modern chemical industry, with oil resources drying up ahead. In the form of such a crisis situation, scientific workers put forward to replace the oil resources in biomass raw materials for reducing the pressure of the decreasing of the world’s oil resources[1]. Reasonable development and utilization of renewable biomass will become the research focus in polymer material field.It also has great significance to the development of the world in the future[2 ~ 20].Poly(ethylene 2,5-furandicarboxylate)(PEF) was synthesized via direct esterification method based on 2,5-furanicarboxylica acid and ethylene glycol. PET-b-PEF block copolymers were prepared by the melt transesterification method, and PET was partly replaced by the PEF polyester. The intrinsic viscosity numbers of PET-b-PEF block copolyesters were test at 25oC by Ubbelohde viscometer; the weight average molecular weight of PET-b-PEF block copolyesterpolyesters were measured by gel permeation chromatography(GPC). Nuclear Magnetic Resonance Spectormeter(NMR), Differential Scanning Calorimeter(DSC), Thermo Gravimetric Analysis(TGA) and X-Ray Diffraction(XRD) were used to characterize the structure, phase-transition temperature,thermostability and crystallinity of the copolyesters.All the Rockwell hardness test, Vicat test, tensile test were used to characterize the mechanical properties copolyesters.1H-NMR confirmed that PET-b-PEF was successfully prepared. DSC showed that the glasstransition temperature(Tg) of copolyesters was about 75.8 to 80.3oC. The Tg of the PET-b-PEF block copolyesters were first decreased and then increased; the crystallinity and the melting temperature were decreased with the increasing contents of PEF segments. TGA showed that the initial decomposition temperature of this series of copolyesters was about 392.2 to407.9oC. It demonstrated that PET-b-PEF block copolyesters had a excellent thermal properties and was similar to that of PET(403.3oC). In addition, the thermal stability of the copolyesters was better than the PET, when the chain segment contents of PEF in the coplyester was less than 15%, and it was close to theinitial decomposition temperature of PET. XRD showed that there was no crystalline diffraction peaks for the copolyesters at the chain segment content of PEF higher than 15%, and it was similar with the results of DSC.All in all, the results of vockwell hardness test, vicat test, and tensile test show that the series block polyester owns good mechanical properties.