Key Laboratory of High Performance Fibers & Products, Ministry of Education, College of Materials Science and Engineering, Donghua University;College of Physics, Donghua University;
The thermotropic liquid crystal polyester(TLCP) fiber is an increasingly important strategic high-performance fiber. In this paper, the TLCP was prepared by two-step melt polymerization using 4-hydroxybenzoic acid(HBA) and 6-hydroxy-2-naphthoic acid(HNA) as comonomers at a molar ratio of 7∶3. The structure of TLCP was confirmed by the Fourier transform infrared(FTIR) spectrometer and nuclear magnetic resonance(NMR) spectrometer. The thermal and rheological properties of TLCP before and after heat treatment were analyzed systematically by the differential scanning calorimeter(DSC), dynamic mechanical analyzer(DMA) and high-temperature rotational rheometer. The results revealed that the melting temperature, glass transition temperature and melt viscosity of the TLCP increased significantly after heat treatment. It indicates that the crystallization of the TLCP is perfect, and solid-phase condensation occurs during heat treatment, which increases its molecular mass. In conclusion, heat treatment at a temperature below but close to the melting temperature can effectively regulate the structure and properties of the TLCP, and the results of this study can provide a reference for the high strengthening of TLCP fibers.
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[1] LYU X L,XIAO A Q,SHI D,et al.Liquid crystalline polymers:discovery,development,and the future[J].Polymer,2020,202:122740.
[2] SCHALLER R,PEIJS T,TERVOORT T A.High-performance liquid-crystalline polymer films for monolithic “composites”[J].Composites Part A:Applied Science and Manufacturing,2016,81:296-304.
[3] KOMATSU S,WETZEL B,FRIEDRICH K.Novel liquid crystal polymers with tailored chemical structure for high barrier,mechanical and tribological performance[M].Cham:Springer,2015:15-39.
[4] RAMATHAL H,LAWAL A.Barrier properties of a thermotropic liquid-crystalline polymer[J].Journal of Applied Polymer Science,2003,89(9):2457-2463.
[5] WEINKAUF D H,PAUL D R.Gas transport properties of thermotropic liquid-crystalline copolyesters.I.The effects of orientation and annealing[J].Journal of Polymer Science Part B:Polymer Physics,1992,30(8):817-835.
[6] WEI P,LI L L,WANG L,et al.Synthesis and properties of high performance biobased liquid crystal copolyesters toward load-bearing bone repair application[J].European Polymer Journal,2022,173:111278.
[7] WANG S Y,MA S N,LI N,et al.Branched thermotropic liquid crystal polymer with favourable processability and dielectric properties[J].European Polymer Journal,2023,196:112302.
[8] THOMPSON D C,TANTOT O,JALLAGEAS H,et al.Characterization of liquid crystal polymer (LCP) material and transmission lines on LCP substrates from 30 to 110 GHz[J].IEEE Transactions on Microwave Theory and Techniques,2004,52(4):1343-1352.
[9] GUAN Q B,LU X,CHEN Y Y,et al.High-performance liquid crystalline polymer for intrinsic fire-resistant and flexible triboelectric nanogenerators[J].Advanced Materials,2022,34(34):e2204543.
[10] PARK G T,CHANG J H,LIM A R.Thermotropic liquid crystalline polymers with various alkoxy side groups:thermal properties and molecular dynamics[J].Polymers,2019,11(6):992.
[11] CHOI E J,LEE S J,JEONG Y G.Effects of mesogenic cycloaliphatic units on the microstructure and properties of thermotropic liquid crystalline polyesters[J].ChemistrySelect,2023,8(1):e202203131.
[12] SONG B S,LEE J Y,JANG S H,et al.Fiber formation and structural development of HBA/HNA thermotropic liquid crystalline polymer in high-speed melt spinning[J].Polymers,2021,13(7):1134.
[13] DONG D W,JIANG S C,NI Y S,et al.Syntheses and properties of thermotropic copolyesters of p-hydroxybenzoic acid[J].European Polymer Journal,2001,37(3):611-617.
[14] LI X G,ZHOU Z L,WU X G,et al.Structure and properties of liquid crystalline naphthalenediol copolyesters[J].Journal of Applied Polymer Science,1994,51(11):1913-1921.
[15] KRIGBAUM W R,HAKEMI H,KOTEK R.Nematogenic polymers having rigid chains.1.Substituted poly(p-phenylene terephthalates)[J].Macromolecules,1985,18(5):965-973.
[16] WEI P,CAKMAK M,CHEN Y W,et al.Aromatic liquid crystalline copolyesters with low Tm and high Tg:synthesis,characterization,and properties[J].Journal of Applied Polymer Science,2014,131(13):40487.
[17] WEI P,CAKMAK M,CHEN Y W,et al.The influence of bisphenol AF unit on thermal behavior of thermotropic liquid crystal copolyesters[J].Thermochimica Acta,2014,586:45-51.
[18] LENZ R W.Synthesis and properties of thermotropic liquid crystal polymers with main chain mesogenic units[J].Polymer Journal,1985,17(1):105-115.
[19] WEI P,LOU H J,YAN J F,et al.Synthesis and properties of high performance aromatic thermotropic liquid crystal copolyesters based on naphthalene ring structure[J].Polymer,2022,240:124472.
[20] BALLAUFF M,SCHMIDT G F.Rigid rod polymers with flexible side chains.2.Observation of a novel type of layered mesophase[J].Die Makromolekulare Chemie,Rapid Communications,1987,8(2):93-97.
[21] PAN Z Y,GAO S X,ZHAO Y F,et al.Processability-enhanced aromatic thermotropic liquid crystalline copolyesters via the introduction of the unsymmetrical units[J].Journal of Applied Polymer Science,2023,140(13):e53659.
[22] WEI P,WANG L,WANG X H,et al.Nonisothermal and isothermal oxidative degradation behavior of thermotropic liquid crystal polyesters containing kinked bisphenol AF and bisphenol A units[J].High Performance Polymers,2014,26(8):935-945.
[23] JACKSON W J Jr.Liquid crystalline polymers.5.Liquid crystalline polyesters containing naphthalene rings[J].Macromolecules,1983,16(7):1027-1033.
[24] LANGELAAN H C,DE BOER A P.Crystallization of thermotropic liquid crystalline HBA/HNA copolymers[J].Polymer,1996,37(25):5667-5680.
[25] PARK S,NA Y J,KIM A Y,et al.Annealing effect of thermotropic liquid crystalline copolyester fibers on thermo-mechanical properties and morphology[J].Scientific Reports,2022,12:13100.
[26] SARLIN J,T?RM?L? P.Heat treatment studies of a TLCP fiber[J].Journal of Applied Polymer Science,1993,50(7):1225-1231.
[27] SARLIN J,T?RM?L? P.Isothermal heat treatment of a thermotropic LCP fiber[J].Journal of Polymer Science Part B:Polymer Physics,1991,29(4):395-405.
[28] KIM Y C,ECONOMY J.The mechanical properties of thermally treated 73/27 HBA/HNA copolyester[J].Polymers for Advanced Technologies,1999,10(8):493-500.
[29] LEE W J,KWAC L K,KIM H G,et al.Thermotropic liquid crystalline copolyester fibers according to various heat treatment conditions[J].Scientific Reports,2021,11:11654.
[30] REYES-MAYER A,ROMO-URIBE A,JAFFE M.Structure evolution of thermotropic polymers by thermal annealing.A light and X-ray scattering study[J].MRS Online Proceedings Library,2015,1765(1):65-70.
[31] SCHNEGGENBURGER L A,OSENAR P,ECONOMY J.Direct evidence for sequence ordering of random semicrystalline copolyesters during high-temperature annealing[J].Macromolecules,1997,30(13):3754-3758.
[32] KAITO A,KYOTANI M,NAKAYAMA K.Effects of draw-down ratio and annealing treatment on structure formation in extruded strands of a thermotropic liquid crystalline copolyester[J].Journal of Macromolecular Science,Part B,1995,34(1/2):105-118.
[33] ROMO-URIBE A,REYES-MAYER A,SARMIENTO-BUSTOS E,et al.Synchrotron scattering and nanoindentation of heat treated high performance thermotropic polymer [J].MRS Advances,2018,3(62):3709-3714.
[34] KIM Y C,ECONOMY J.The degradation process observed during step annealing of 73/27 HBA/HNA copolyester[J].Macromolecules,1999,32(9):2855-2860.
[35] ROMO-URIBE A,REYES-MAYER A,CALIXTO RODRIGUEZ M,et al.On the influence of thermal annealing on molecular relaxations and structure in thermotropic liquid crystalline polymer[J].Polymer,2022,240:124506.
[36] REYES-MAYER A,ALVARADO-TENORIO B,ROMO-URIBE A,et al.SALS,WAXS and mechanical properties of heat-treated thermotropic polymers[J].Polymers for Advanced Technologies,2013,24(12):1029-1039.
[37] ROMO-URIBE A,WINDLE A H.Melt viscosity of main-chain thermotropic liquid crystalline polymers without flexible spacers[J].Macromolecules,1995,28(21):7085-7087.
[38] HEBERER D P,ODELL J A,PERCEC V.Rheology and flow-induced liquid crystal phase transitions in thermotropic polyethers[J].Journal of Materials Science,1994,29(13):3477-3483.
[39] KAITO A,KYOTANI M,NAKAYAMA K.Effects of annealing on the structure formation in a thermotropic liquid crystalline copolyester[J].Macromolecules,1990,23(4):1035-1040.
[40] WARNER S B,LEE J.Towards understanding the increase in strength of thermotropic polyesters with heat treatment[J].Journal of Polymer Science Part B:Polymer Physics,1994,32(10):1759-1769.
Basic Information:
DOI：10.19884/j.1672-5220.202405016
China Classification Code:TQ342.724
Citation Information:
[1]董世航,陈宇锋,万海等.热处理工艺对热致液晶聚芳酯分子量及热性能的影响（英文）[J].Journal of Donghua University(English Edition),2025,42(02):124-135.DOI:10.19884/j.1672-5220.202405016.
Fund Information:
National Key Research and Development Program of China (No. 2021YFB3700105)