Crystallization properties of polyethylene terephthalate-2,5-furandicarboxylic acid copolyesters
A series of polyethylene terephthalate-2,5-furandicarboxylic acid copolymers(PEFT)with different DMF contents were prepared by ester-exchange-melt-condensation method using dimethyl 2,5-furandicarboxylic acid(DMF),ethylene glycol terephthalate(DMT)and ethylene glycol(EG)as the raw materials and antimony ethyl-ene glycol as the catalyst.The melting points and crystallinity of the PEFT copolymers,and PEF pre-crystallized at temperatures between 150 and 180℃for 10 to 40 min were analyzed by differential scanning calorimetry(DSC)and X-ray diffraction(XRD).The results showed that PEFT and PEF were best pre-crystallized at 170℃without adhe-sion while maintaining a fast crystallization rate.When the DMF copolymerization ratio is lower than 15%or higher than 95%,the PEFT copolymers has certain crystalline properties.When the copolymerization ratio is between 15%～95%,the PEFT copolymers belongs to the amorphous structure and is difficult to crystallize.When the DMF copoly-merization ratio is lower than 15%,the PEFT co-polyester maintains the same crystal structure as PET.When the DMF copolymerization unit ratio is higher than 95%,PEFT and PEF to maintain the same crystal structure,and the small amount of copolymerization monomers introduced won't change the crystalline structure of polyester.
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