T-ZnOw/TLCP抗静电复合材料的制备与性能研究

以热致液晶高分子(TLCP)为基体,四针状氧化锌晶须(T-ZnOw)为导电填料,用单螺杆挤出机制备抗静电性T-ZnOw/TLCP复合材料,分别探讨了偶联剂对T-ZnOw的影响;T-ZnOw用量对T-ZnOw/TLCP复合材料表面电阻率、热变形温度、力学性能的影响。结果表明,T-ZnOw经过偶联剂改性后,随着其用量的增加,复合材料表面电阻率显著下降,热变形温度、拉伸强度、冲击强度均呈现先增大后减小的趋势。     

PA66/TLCP/HNTs纳米管复合材料的制备与性能

采用熔融共混方法制备了尼龙(PA)66/热致液晶聚合物(TLCP)/埃洛石纳米管(HNTs)复合材料,研究了其热性能、微观形态及力学性能.结果表明,当TLCP的质量分数为4%、HNTs的质量分数为15%时,复合材料的综合性能最佳.其拉伸强度、拉伸弹性模量、弯曲强度及弯曲弹性模量相比纯PA66分别提高了30.4%、76.9%、34.4%、91.7%.熔体的加工流动性得到改善,PA66/TLCP/HNTs复合材料的吸水性能明显降低.少量的TLCP有利于提高PA66/TLCP复合材料的结晶性能和熔融温度;HNTs的加入能提高复合材料的结晶温度,与基体有较好的界面结合;TLCP及HNTs能在基体中均匀地分散,TLCP在PA66/TLCP/HNTs复合材料中形成微纤结构,且沿纤维轴方向取向.     

PA6原位成纤改善PPR的挤出流变性能

采用原位成纤复合法制备了无规共聚聚丙烯(PPR)/尼龙6(PA6)复合样品,研究了PA6的原位微纤化对PPR熔体挤出流变性能的影响。结果表明,采用的"挤出-热拉伸-淬冷"工艺可实现PA6在PPR基体中的原位微纤化;少量PA6对PPR的挤出螺纹畸变有改善效果;添加相容剂PP-g-MAH(马来酸酐接枝聚丙烯)有利于改善PPR和PA6两相的界面相容性,并明显改善PPR的挤出螺纹畸变。当PA6质量分数为5%时,加入PP-g-MAH后挤出物外观质量较好,出现螺纹畸变的"临界"表观剪切速率从246s-1增大到719s-1。     

聚苯硫醚／热致液晶高分子共混体系的结构与性能研究

本文研究了聚苯硫醚(PPS)与两种热致型液晶聚合物(TLCP)共混体系的热性能、力学性能及形态。结果表明,TLCP的加入对于PPS的结晶性及热稳定性都有一定影响。当半芳聚酯类液晶用量少于5份时,共混体系的力学性能优于纯PPS。形态表明,共混物中的TLCP多以取向度较小的椭球体形式存在。     

TLCP/GF混杂增强聚醚砜酮复合材料的研究

用热致性液晶聚合物(TLCP)和玻璃纤维(GF)对二氮杂萘酮联苯结构聚醚砜酮(PPESK)进行混杂增强改性,用双螺杆挤出机通过熔融共混的方式制备了改性PPESK复合材料。研究了PPESK/TLCP、PPESK/TLCP/GF复合材料的加工性能和力学性能,并对复合材料的拉伸断面形貌进行观察。结果表明,随着TLCP用量的增加,熔体的粘度逐渐降低,加工流动性得到改善;TLCP/GF的混杂增强使PPESK复合材料的拉伸强度得到一定提高,冲击强度有所降低;TLCP用量小于10份时,TLCP以球状粒子或棒状形式存在,当TLCP用量为20份时,TLCP在材料中形成直径为亚微米数量级的高长径比微纤。     

抗静电热致液晶高分子的制备与性能研究

将碳纤维与热致液晶高分子(TLCP)经成型加工制得样条,24 h后测试样条的表面电阻率、熔点、结晶度,并考察碳纤维的加入对液晶高分子力学性能的影响。结果表明:TLCP表面电阻率随碳纤维含量的增加而下降,当碳纤维含量达到20%时,材料的表面电阻率最低,抗静电效果最佳;碳纤维的加入使结晶度稍有提高,拉伸强度提高明显,但是TLCP的冲击强度有所降低。     

复合纤维及异形纤维

975232 在复合纤维纺丝时结构—性能的发展 Robertson C.G.…;Annu.Teeh.Conf.一Soe. plast.Eng.,1996,SAth(Vol.2),p.1558一1562(英) 两种新方法用非重叠的加工温度由Protax6823间 规聚丙烯(PP)和热致液晶聚合物(TLCP)Vectra B950(一种无规聚醋/聚酞脂)制备拉伸复合纤维。 一种方法为了获得具有皮/芯结构的纤维,在熔纺之 前单一的TLCP熔体流被PP皮包围。另一种方法 包括连续的TLCP熔体流在分别塑化的PP熔体内 分布以形成复合熔体,该熔体被拉伸产生由VB原 纤增强的PP母体组成的母体/原纤纤维。仅管有明 显不同的加工温度,VB…     

PA66／TLCP原位复合材料的热性能、形貌及力学性能研究

通过挤出和注射成型制备了聚酰胺66／热致液晶聚酰胺（PA66／FLCP）原位复合材料，研究了其热性能、形貌及力学性能。DSC分析表明，PA66和TLCP相容性较好，随着TLCP含量的增加，PA66的结晶度、结晶速率下降；SEM分析表明，TLCP在PA66基体中分散均匀，两相相容性较好，当加入10％（质量分数，下同）的TLCP时，TLCP形成长径比比较大的纤维；拉伸试验结果表明，当加入TLCP后，PA66的力学性能有明显的改善。当加入10％的TLCP时，共混物的力学性能增幅最大，拉伸强度增加79．6％，拉伸模量增加120．4％，断裂伸长率明显下降。     

TLCP/PA66复合材料的熔融和结晶行为

双螺杆挤出制备热致液晶/尼龙 66(TLCP/PA66)复合材料,示差量热扫描(DSC)和X射线衍射(XRD)对复合材料的熔融和结晶等行为进行分析.结果表明:低含量的TLCP存在成核剂的作用使复合材料具有较高的结晶温度、结晶度以及完美的结晶形态;受到TLCP刚性分子链的影响,高含量TLCP使复合材料的熔点、结晶温度和结晶度等参数下降.XRD分析结果表明:TLCP促进复合材料晶体沿(010)和(110)面生长.     

热致性液晶聚芳酯纤维的制备与结构研究

介绍了利用低分子质量和高分子质量热致性液晶聚芳酯(TLCP),通过熔融纺丝制备TLCP初生纤维的加工工艺及后处理方法,分析了纺丝过程中TLCP熔体在喷丝板下方的形变过程,并通过扫描电镜、广角X-射线衍射仪、纤维强度仪对TLCP纤维的结构和性能进行表征,为热致性TLCP纤维的工业化提供了可靠的工艺参数.     

Structure and property relationship of thermotropic liquid crystal polymer and polyester composite fibers

Poly(ethylene 2,6‐naphthalate) (PEN) and poly(ethylene terephthalate) (PET) composite fibers reinforced with a thermotropic liquid crystal polymer (TLCP) were prepared by the melt blending and spinning process to achieve high performance fibers with improved processability. Polymer composite fibers consisting of cheap polyester and small quantity of expensive TLCP are of interest from an economic point of view and from an industrial perspective. The increase in the birefringence and density of the TLCP/PEN/PET composite fibers with the spinning speed was attributable to the enhancement of the molecular orientation and effective packing between chains in the TLCP/PEN/PET composite fibers. Annealing process resulted in the formation of more ordered and perfect crystalline structure and higher crystallinity, improving the mechanical properties of the TLCP/PEN/PET composite fibers. The increase in the crystallite size and the degree of chain extension with increasing spinning speed resulted in the gradual increment of the long period for the TLCP/PEN/PET composite fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006.     

Structure and properties of thermotropic liquid crystal polymer and poly(ethylene 2,6‐naphthalate) blend fibers

BACKGROUND: The melt blending of thermotropic liquid crystal polymers (TLCPs) using conventional thermoplastics has attracted much attention due to the improved strength and tensile modulus of the resulting polymer composites. Moreover, because of their low melt viscosity, the addition of small amounts of TLCPs can reduce the melt viscosity of polymer blends, thereby enhancing the processability. RESULTS: In this study, TLCP/poly(ethylene 2,6‐naphthalate) (PEN) blend fibers were prepared by melt blending and melt spinning to improve fiber performance and processability. The relation between the structure and the mechanical properties of TLCP/PEN blend fibers and the effect of annealing on these properties were also investigated. The mechanical properties of the blend fibers were improved by increasing the spinning speed and by adding TLCP. These properties of the blend fibers were also improved by annealing. The tensile strength of TLCP5/PEN spun at a spinning speed of 2.0 km h^?1 and annealed at 235 °C for 2 h was about three times higher than that of TLCP5/PEN spun at a spinning speed of 0.5 km h^?1. The double melting behavior observed in the annealed fibers depended on the annealing temperature and time. CONCLUSION: The improvement of the mechanical properties of the blend fibers with spinning speed, by adding TLCP and by annealing was attributed to an increase in crystallite size, an increase in the degree of crystallinity and an improvement in crystal perfection. The double melting behavior was influenced by the distribution in lamella thickness that occurred because of a melt‐reorganization process during differential scanning calorimetry scans. Copyright © 2007 Society of Chemical Industry     

Compatibilizers for thermotropic liquid crystalline polymer/polyolefin blends prepared by reactive mixing: The effect of processing conditions

The effect of processing conditions on the melt formation of a graft‐copolymer compatibilizer for blends of a thermotropic liquid crystalline polymer (TLCP) and polyolefins was investigated. The compatibilizer was formed by a melt acidolysis reaction of a 50/50 (w/w) blend of TLCP and the sodium salt of a poly(ethylene‐coacrylic acid) ionomer. The effects of various processing conditions in a batch mixer and a single‐screw extruder on the extent of reaction were assessed. The extent of graft‐copolymer formation and the efficacy of the product as a compatibilizer for TLCP/polyethylene blends were affected by the processing temperature and the screw (or rotor) speed.     

PPS/TLCP共混体系结构与流变研究

采用热致液晶聚合物（TLCP）与聚苯硫醚（PPS）熔融共混的方式制备了PPS／TLCP复合材料,研究了PPS／TLCP共混体系的形貌、流变性能以及加工参数对微纤形成的影响。结果表明：TLCP可明显改善体系的加工特性,并能原位生成微纤化复合材料,TLCP对体系黏度有较大影响,在低剪切速率区黏度下降幅度较大,在高剪切速率区,黏度降低幅度小。PPS／TLCP复合材料存在皮芯结构,工艺参数对TLCP微纤的形成起着重要作用,通过提高注塑速度,对TLCP微纤的形成特别有利。     

TLCP含量对TLCP/PF复合体系固化反应动力学的影响

采用非等温DSC方法研究了不同升温速率下热致性液晶聚酯酰亚胺(TLCP)/酚醛树脂(PF)复合体系的固化行为,利用3种现象学模型(Ozawa及Kissinger简单模型、Kissinger-Akahira-Sunose(KAS)等转化模型)分析对比了TLCP/PF复合体系及纯PF体系的固化反应动力学,研究了不同含量的TLCP对TLCP/PF复合体系固化反应动力学的影响。结果表明:采用Ozawa和Kissinger 2种方法计算得到的TLCP/PF复合体系的固化反应活化能(Ea)结果一致;TLCP的加入一定程度上影响了PF的固化反应,改变了PF的Ea;当TLCP的质量分数为3%时,Ea最小。     

Hierarchical structure of thermotropic liquid crystalline polymer formed in blends jointly by dynamic and thermodynamic driving forces

The hierarchical structure of thermotropic liquid crystalline polymer (TLCP), especially microfibrils with an average diameter of 30 nm has been obtained in polyamide 6 (PA6)/TLCP/glass bead (GB) ternary blends by capillary flows. Thermodynamically the different interfacial tensions between PA6 and GB, and between TLCP and GB, make the glass beads migrate to the vicinity of the TLCP melt droplets. Then the strong extensional flow field formed by the micro-rollers of these glass beads exerts strong extensional action on TLCP coils so that results in the formation of TLCP microfibrils, which are usually generated with neat TLCP melt only. The hierarchical structure of thermotropic liquid crystalline polymer (TLCP) in PA6/TLCP/GB ternary blends can enhance mechanical performance of such blends.     

Reinforcement of mechanical properties of a poly(ethylene terephthalate) and polycarbonate blend by the addition of thermotropic liquid crystalline polymer

Mechanical properties of the ternary blends of poly(ethylene terephthalate) (PET), polycarbonate (PC), and thermotropic liquid crystalline (TCLP, Vectra A950) were investigated. The ternary blends were prepared by varying the amount TLCP but fixing the ration of PET and PC. The fiber fallen freely through the capillary die had the highest initial modulus (1.46 GPa)/tensile strength (73 MPa) when 10% of TLCP was added. Above this TLCP content, however initial modulus and tensile strength decreased. The scanning electron microscope (SEM) micrographs of the TLCP phase which was extracted by dissolving PET/PC matrix from the blend showed the fine fibrils formed at 5 and 10% of TLCP, while the aggregated TLCP phases at 20 and 30% of TLCP. It was suggested that the decrease of the mechanical properties of the resulting blend was caused by the aggregation of TLCP phase above 10% of TLCP. A high draw ratio gave a rise to the formation of highly oriented fibrils of TLCP phase in the PET/PC matrix and the improvement of mechanical properties of the ternary blend.     

Influence of viscosity ratio on processing and morphology of thermotropic liquid crystal polymer‐reinforced poly(ethylene 2,6‐naphthalate) blends

Thermotropic liquid crystal polymer (TLCP) microfibril‐reinforced poly(ethylene 2,6‐naphthalate) (PEN) composites with various intrinsic viscosities were prepared by a melt compounding method. Polymer composites consisting of bulk cheap polyester with a small amount of expensive TLCP are of interest from a commercial perspective. The TLCP acts as a nucleating agent in the TLCP/PEN composites, enhancing the crystallization of the PEN matrix through heterogeneous nucleation. The structural viscosity index of the TLCP/PEN composites was lower than that of PEN and TLCP, which was attributed to the formation of TLCP fibrillar structures with elongated fibrils in the PEN matrix. The TLCP/PEN composites with higher intrinsic viscosity than the polymer matrix contained these elongated fibrils, and had a TLCP component with a smaller average diameter, and a narrower diameter distribution than TLCP/PEN composites with lower intrinsic viscosity. The higher intrinsic viscosity of the polymer matrix, the higher shear rate and the lower viscosity ratio of TLCP to PEN can all favour TLCP fibrillation in the polymer composites. Copyright © 2006 Society of Chemical Industry     

Fabrication of High Performance PET/TLCP Fibers through the Synergistic Interfacial Enhancement and Compatibilization of Functional 1D and 2D Carbon Nanomaterials

The maleic anhydride functionalized graphene oxide (GO-MA) is fabricated by an efficient and solvent-free Diels–Alder reaction. Polyethylene terephthalate (PET)/thermotropic liquid crystal polyester (TLCP), PET/TLCP/GO-MA, PET/TLCP/aminated multi-walled carbon nanotubes (MWCNTs-NH₂), and PET/TLCP/GO-MA/MWCNTs-NH₂ composite fibers are systematically melt-spun. The structure and compatibilizing effects of GO-MA and MWCNTs-NH₂ on the mechanical, thermal, and crystallization properties of the composite fibers are indicated. The non-isothermal crystallization kinetics and X-ray diffraction (XRD) data show that TLCP and nanofillers can change the crystalline morphology of PET. The mechanical properties of the fibers rise with increasing TLCP content. The tensile strength 929 MPa and modulus 17.5 GPa of the fibers with 7 wt% TLCP and 0.25 wt% nanofillers (0.1 wt% GO-MA and 0.15 wt% MWCNTs-NH₂) are significantly higher than those with 7 wt% TLCP (tensile strength 622 MPa and modulus 16.1 GPa) and even higher than those with 15% TLCP (tensile strength 836 MPa, and modulus 18.0 GPa). When the GO-MA and MWCNTs-NH₂ co-exist, the anti-dripping phenomenon is improved. Therefore, the TLCP, GO, and MWCNTs synergistically strengthens the mechanical properties. This is promising for the industrial fabrication of high-strength fibers.     

Morphology evolution of a thermotropic liquid‐crystalline polymer in a polyamide 6,6 matrix regulated by graphene

A two‐step process, thermotropic liquid‐crystalline polymer (TLCP) premixing with reduced graphene oxide (RGO) followed by blending with polyamide 6,6 (PA66), was used to prepare ternary TLCP/RGO/PA66 blends. The rheological behaviors, morphology, and mechanical properties of the blends were investigated. The results show that RGO migrated from the TLCP phase to the interface between the TLCP and PA66 phase during melt blending; this was due to a similar affinity of the RGO nanosheets to both component polymers. The dimensions of the dispersive TLCP domains were markedly reduced with the mounting RGO content; this revealed a good compatibilization effect of RGO on the immiscible polymers. The hierarchical structures of the TLCP fibrils were found in both the unfilled TLCP/PA66 blends and TLCP/RGO/PA66 blends. This supposedly resulted from the extensional and torsional action of unstable capillary flow. With the addition of RGO, the viscosities of the blends decreased further, and the fibrillation of TLCP and the mechanical performance of TLCP composites were both enhanced. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43735.