Sythesis And Properties Of Multiple Co-polyether Esters

Thermoplastic polyether ester elastomer(TPEE)is a multi-block linear copolymer,of which TPEE with polybutylene terephthalate(PBT)as the hard segment and polytetrahydrofuran(PTMG)as the soft segment has excellent elasticity,thermal stability and high strength and high toughness.With the expansion of TPEE application fields,the demand for its material and product performance is getting higher and higher.Therefore,there is an urgent need to optimize the synthesis process of TPEE,as well as to deepen the research on the structure and properties of TPEE,and to develop special and multifunctional polyether ester elastomer materials by regulating the ratio of soft and hard segments and modification research,in order to overcome the different properties required for them in different fields,so as to improve the market competitiveness of TPEE.To this end,two main areas of work are carried out in this paper.The first part is the synthesis of polybutylene terephthalate(PBT)-b-polytetrahydrofuran(PTMG)polyether ester block copolymers(TPEE)by introducing macromolecular polyethers(PTMG)into the PBT macromolecular chain.In the second part,isophthalic acid(IPA)and adipic acid(AA)were introduced into the hard segment of TPEE,respectively,and the corresponding P(BT-co-BI)-b-PTMG and P(BT-co-BA)-b-PTMG polyco-polyether esters were synthesized and named as TPEEI and TPEEA,respectively.The main work and results of the structural characterization and performance testing of the produced products are as follows:(1)A series of TPEEs with different soft and hard segment contents were synthesized by using direct esterification instead of the conventional ester exchange method,with terephthalic acid(PTA)and 1,4-butanediol(1,4-BDO)as raw materials,polytetrahydrofuran(PTMG)of different molecular weights as copolymer monomers,and n-tetrabutyl titanate(TBT)as catalyst,to explore the effects of different soft and hard segment mass ratios and soft segment molecular weights on the material The effects of different soft and hard segment mass ratios and soft segment molecular weight on the sequence structure and molecular weight,thermal and mechanical properties of the materials were investigated.The experimental results showed that:infrared spectroscopy(FT-IR)and nuclear magnetic resonance hydrogen spectroscopy(~1H-NMR)analysis showed that PTMG had been involved in the polycondensation reaction,but thermal degradation of PTMG occurred during the synthesis process,and the degree of thermal degradation was related to the molecular weight of PTMG;the characteristic viscosity tests showed that the characteristic viscosity of TPEE was higher than that of PBT,and decreased with the increase of the mass fraction of the hard segment or the molecular weight of the soft segment;differential Scanning calorimetry(DSC)tests showed that the melting point of TPEE decreased with the increase of the molar content of the soft segment,and the results of dynamic thermomechanical analysis(DMA)confirmed the microphase separation structure in TPEE.The thermal weight loss(TG)test shows that TPEE has good thermal stability;tensile and impact resistance tests show that TPEE has good mechanical properties and shows high strength and high toughness.(2)In order to regulate the crystalline properties of TPEE,on the basis of maintaining the same content of soft and hard segments,PTA,BDO and PTMG1000were used as raw materials and TBT was used as catalyst,and IPA and AA were introduced as copolymer monomers during the melt polymerization process to synthesize a series of TPEEI and TPEEA multi-polyether esters with different copolymerization ratios,mainly to investigate their chemical structures and different compositions.The chemical structures,thermal properties and crystallization behaviors of the copolyether esters with different compositions were investigated.The experimental results showed that:~1H-NMR confirmed that the products were TPEEI and TPEEA,and their actual compositions were basically the same as the feed ratios,and the thermal degradation of PTMG was more serious during the polymerization of TPEEA series samples;DSC tests showed that the melting points of both copolyether esters tended to decrease with the increase of the copolymerization ratio and the decrease was basically the same,but the thermal crystallization temperature of TPEEA was significantly lower under the same copolymerization ratio.The thermal crystallization temperature of TPEEA is significantly higher than that of TPEEI at the same copolymerization ratio,and the difference can be 17℃when the copolymerization ratio is 20%.Optical microscopy(PLM)tests showed that the addition of copolymer monomer destroyed the crystallization properties of TPEE,and the crystalline morphology changed from large size and clear cross extinction to small size and fuzzy bright spots with the increase of copolymerization ratio;melt index tests showed that the melt fluidity of TPEEA at 230℃was higher than that of TPEEI with the same copolymerization ratio,and the difference increased with the increase of copolymerization ratio.