Preparation And Characterization Of Bio-based Poly(Dihydric Alcohol 2,5-Furandicarboxylate) And Fibers

The polyester industry is an important industry that is related to the national economy and people's livelihood,polyester products are broadly utilized in every sector of industries,consisting in man-made fiber,electronics fabrication,construction and light industry.Among many compounds,polyethylene terephthalate(PET)is most familiar polyester product to every profession,which is principally choose the monomers derived from petroleum.With the people's thorough awareness of sustainable development and the enforcement of"carbon peak and neutrality"strategic objectives put forth by China's government,all sorts of fields have to reduce the usage of petroleum.Fortunately,recently,bio-based polyester has attracted widespread attention for its advantages in raw material sources,environmental benefits,and energy consumption,and some industries are considering replacing petroleum-based products with bio-based merchandises.2,5-furandicarboxylic acid(FDCA)is the promising monomer material collected form the natural resources,whose chemical structure is way too similar to that of petroleum-borne terephthalic acid(PTA),that can be applied as the perfect alternative to PTA.With the maturity of FDCA synthesis and purification technology,furan-based polyester has drawn wide attention in various fields and become a mainstream of bio-based polymer materials,concentrating on the homogeneous and conjugated polymers based on furans.As an efficient and economical polymerization method,melt polycondensation has been widely used in producing polyester.At present,in the packaging materials field,some poly(ethylene 2,5-furandicarboxylate)(PEF)has replaced the petroleum-based PET,though the researches of full bio-based poly(propylene 2,5-furandicarboxylate)(PTF)are still less,there are only a few reports about PEF and PTF application in the fiber field,mainly because the easy oxidation and degradation of furan ring structure in furan-based polyester at high temperature,which leads to the molecular weight difficult to improve and the serious yellowing phenomenon of the products.Therefore,the study and preparation of high molecular weight furan-based polyester and its fibers have scientific and practical significance.In this paper,PEF and PTF with high molecular weight are synthesized,the fundamental properties of bio-based polyester are investigated,then different catalysts'effects,polymerization processes on PEF,PTF structure,and performance are studied,and the fiber properties are researched.The detailed results are concluded as follows:In the study of PEF synthesis,PEF was synthesized by different catalysts and polymerization processes,PEF suitable for spinning was prepared by using a zinc acetate-tetrabutyl titanate combined catalyst.The produced PEF's mean molecular weight(M_n)is nearly 30,000 and polymer dispersity index(PDI)is less than 3.FTIR and ~1H-NMR analysis are adopted to characterize the structure;DSC and TGA tests are conducted to characterize the polyester's thermal properties.The test outcomes reveal that fabricated polyester samples possess a T_g ranging from 90 to 92°C,melting point T_m about 210-212°C and initial thermal decomposition temperature exceedingly over 370°C,that suggests the fiber has good thermal stability.The crystallization behavior of PEF is also studied,the isothermal crystal dynamics test implies that PEF's crystallization rate is regularly slower than that of PET.In the study of PTF synthetic,full bio-based PTF was prepared by using the interesterification melt polycondensation method and the combination catalyst of zinc acetate-titanium tetrabutylate.with a mean molecular weight of more than 35,000.Still,FTIR and ~1H-NMR analysis were adopted to characterize chemical structure;DSC and TGA tests are conducted to characterize polyester's thermal properties.Final consequences reveal that produced polyester possess a T_granging from 60 to 62°C,melting point(T_m)about 170°C,and initial thermal decomposition temperature exceedingly over 370°C,which implies PTF has good thermal stability.Besides,the PEF and PTF fibers were through the two-step method(UDY-DT)and research the effect of various drawing ratios on the mechanical strength of fabricated fibers.Tests outcomes indicate that the maximum fracture strength of PEF fiber could reach up to 2.17c N/dtex,basically meeting its application in the textile field while the maximum fracture strength of PTF fibers is only 0.48 c N/dtex,making it difficult to be applied in the textile industry.