尼龙6/液晶聚合物共混体系中化学反应对体系热行为及形貌的影响

采用漫反射红外光谱法(DRIFT)和示差扫描量热法(DSC)研究了2种不同特性黏数的尼龙6与3种液晶聚合物(Vectra A950、Vectra B950和Rodrun LC5000)之间的酯-酰胺交换反应.DRIFT测试证实了尼龙6与LC5000之间存在化学反应.DSC分析表明,酯-酰胺交换反应使体系中尼龙6的熔点下降、结晶度降低.增加反应时间和增大共混体系中液晶聚合物的含量有利于酯-酰胺交换反应的发生.与Vectra A950和Vectra B950相比,分子链柔性较强的Rodrun LC5000与尼龙6之间的化学反应更容易进行.扫描电子显微镜(SEM)观察表明,随着共混时间的延长,分散相形貌由球状粒子发展为短棒状纤维,乃至最终形成直径更细的微纤结构.     

THERMAL ANALYSIS AND STRUCTURE STUDIES ON THE BLENDS OF LIQUID CRYSTALLINE COPOLYESTERS AND PET, PBT

The apparent uniform blends of liquid crystalline aromatic copolyesters and semiflexible polyesters PET or PBT were obtained by mechanical mixing in the molten state within certain range of composition.The effects of blending with liquid crystalline components on the structure of homopolyester matrix were examined by thermal analysis and X-ray diffraction. These results suggest that the LC component in the blend may possibly be acting as a nucleating agent, or it may induce axial orientation of molecules promoting the local ordering of matrix. For the blends of PET, these influences mainly display in narrowing the width of cold crystalline peak and enhancing the main peak of x-ray diffraction; and for the blends of PBT, the pre-melting crystalline peak was enhanced.     

ADVANCES IN LIQUID CRYSTALLINE POLYESTERS

Advances have been made in understanding the interactions of composition, molecular weight, liquid crystallinity,orientation, and three-dimensional crystallinity on the properties of injection-molded and melt-spun liquid crystalline polyesters (LCP's). Two classes of potentially low-cost LCP's were compared:(1) semiflexible LCP's prepared from 1,6-hexanediol and the dimethyl ester of either trans-4, 4'stilbenedicarboxylic acid or 4.4 ' biphenyldicarboxylic acid and (2) all-aromatic LCP's prepared from terephthalic acid, 2, 6-naphthalenedicarboxylic acid, the diacetate of hydroquinone, and the acetate of p-hydroxybenzoic acid. The effects of composition on the plastic properties of the 4-component all-aromatic LCP's were determined with the aid of a 3 x 3 factorial statistically designed experiment, the generation of equations with a computer program, and the plotting of three-dimensional figures and contour diagrams. The effects of absolute molecular weight (M_w) on the tensile strengths of the semiflexible LCP's and one of the all-aromatic LCP's having an excellent balance of plastic properties were also compared, and it was observed that the semiflexible LCP's required M_w's about 4 times higher than the all-aromatic LCP to attain a given strength. Persistence lengths and molecular modeling were used to explain these differences.     

环氧树脂/液晶聚合物体系的形态、力学性能和热稳定性

合成了一种端基含有活性基团的热致性液晶聚合物 (LCPU) ,用其改性环氧树脂CYD 12 8 4 ,4′ 二氨基二苯砜 (DDS)固化体系 ,对改性体系的冲击性能、拉伸性能、弯曲性能、弹性模量、断裂伸长率、玻璃化转变温度Tg、热失重温度TG与LCPU含量的关系进行了探讨 ,对不同种类液晶化合物改性CYD 12 8 DDS体系效果进行了比较 ,用扫描电镜 (SEM)研究了材料断面的形态结构 .结果表明 ,LCPU的加入可以使固化物的力学性能和热稳定性提高 ,改性后材料断裂面的形态逐渐呈现韧性断裂特征     

聚劳酯液晶硬核的构象与键级的理论研究

液晶已有一百年的历史了。液晶化学,液晶物理,液晶材料方面的科学都有了相当丰富的积累与长足的发展。十三年前Chandrase khar发现了碟形液晶,它具有特征的二维有序的柱状液晶相。从学术上讲,该发现对液晶科学的一些概念有一定的冲击,传统的有关液晶的分类(向列型、胆甾型、近晶型)正在被更加合理的从液晶分子聚集结构的几何特性而进行的分类(向列相、层状相、柱状相)所取代。这些进展鞭策着人们去追本求     

液晶冠醚LB膜的制备及其性质研究

本文首次研究了五种新合成的液晶冠醚ＬＢ膜的成膜特性。实验发现，其中的单臂胆甾型液晶冠醚在气－液界面易形成稳定的单分子膜，但不易累积形成ＬＢ膜；芳香酯类的单臂液晶冠醚膜的稳定性与链的长短有关；而双臂芳香酯型二氮杂１８－冠－６易形成稳定的膜，且具有特殊的相变性质。膜的特性与物质的化学结构有关，借助ＣＰＫ分子模型，对成膜后分子构型进行了估算，理论计算与实验一致。对纯组分以及单臂液晶冠醚与硬脂酸的混合膜结构，用表面压－面积曲线以及小角Ｘ衍射等进行了表征，并对其中的双臂液晶冠醚作了离子识别功能研究。     

STUDY OF CHIRAL SIDE CHAIN LIQUID CRYSTALLINE POLYMERS

Five kinds of side chain liquid crystalline polymers with a chiral component in the pendant group were synthesized and characterized by GPC, polarizing microscopy, DSC, X-ray diffraction ano Dielectric Relaxation Spectroscopy. The liquid crystalline behaviour of the polymers is affected by the length of flexible spacer, which links the mesogenic side chain to the polymer backbone and mesogenic moiety. The characteristic of smectic phase is observed for all the polymers.     

液晶聚酯与环氧嵌段共聚物的合成及表征

近年来 ,人们利用高分子液晶作为热固性环氧树脂的改性剂 ,不仅可以提高环氧树脂的韧性和强度 ,而且可以改善其热性能 ,为制备高性能的环氧树脂提供了一条新的途径[1,2 ] .目前报道所使用的液晶聚合物大多为液晶聚酯[3 ] 或液晶性聚氨酯[4] ,这些液晶聚合物与环氧树脂由于存在相容性不好的问题 ,给其实际应用带来了困难 .为了改善二者的相容性 ,本文采用溶液法合成了末端带有反应活性基团的聚酯型液晶聚合物 ,将它再与双酚Ａ环氧预聚物反应 ,制得了高分子液晶环氧嵌段共聚物 ,其合成路线如下 :2ＨＯＣＯＯＣＨ3+ ＨＯ(ＣＨ2 ) 6 ＯＨ　　Ｈ…     

全芳香族共聚酯的结构和其液晶行为研究

本文对不同组成的对苯二甲酸(TPA),对羟基苯甲酸(PHBA),联苯二酚(BP),间苯二甲酸(IPA)共聚酯采用热台偏光显微镜、电子显微镜、X-射线衍射、激光小角散射、差热等技术进行了研究.实验结果表明,在一定的组成范围内共聚酯熔体有很好的液晶性.重点讨论了分子组成、转变行为、液晶性的关系,并对液晶相的形态结构进行了表征.     

EFFECT OF DRAWING ON MORPHOLOGY,STRUCTURE AND MECHANICAL PROPERTIES OF BLENDS OF A LIQUID CRYSTALLINE POLYMER AND MODIFIED POLY(PHENYLENE OXIDE)

Polymer strands with various draw ratios of a thermotropic liquid crystalline polymer(LCP) and modified poly(phenylene oxide) were prepared by drawing the melts leaving aslit die in open air. The morphology, structure and mechanical properties of the resultingstrands were studied as a function of LCP content and draw ratio. It was found that thethermal and mechanical properties of the matrix phase did not change dramatically withthe amount of LCP and draw ratio, but the orientation of LCP phase could be increasedwith draw ratio. The mechanical properties of the strands could be improved by moderatelydrawing the melts. Wide angle X-ray diffraction suggested that the improvement in tensilestrength of the strands was due to the resultant fibrillation of LCP phase and enhancedmolecular orientation. Morphological observation indicated that excessive drawing of thestrands could lead to the break down of the microfibrils of LCP and thus resulted in thedecrease of mechanical strength.     

手性聚甲基丙烯酸酯液晶聚合物的合成及相行为的研究

手性聚甲基丙烯酸酯液晶聚合物的合成及相行为的研究向前，张纪宇，张树范（中国科学院化学研究所北京１０００８０）关键词手性液晶聚合物，相行为手性侧链液晶聚合物在侧链中含有不对称碳原子的末端基，使聚合物显示Ｓｔ相．Ｓ？相层中的分子呈倾斜排列而产生自发极化．...     

聚苯撑苯并二噻唑的甲基磺酸溶液的相转变过程及其动力学研究

用退偏振光强度法及偏光显微镜研究了溶致性液晶高分子聚苯撑苯并二噻唑的甲基磺酸溶液(PBT/MSA)由液晶相至各向同性相(N→I转变),及由各向同性相至液晶相(I→N转变)的相变过程.液晶相的形成(I→N)服从Av-rami方程,Avrami指数为1左右,表明该体系的液晶相是以一维棒状方式形成的.相转变温度与浓度有关,提高温度可加速在应力下液晶相长程有序结构的形成.     

MORPHOLOGICAL STUDY ON THE ORIENTED CHITOSAN FILM OBTAINED FROM PRE-SHEARED LIQUID CRYSTALLINE SOLUTION IN DICHLOROACETIC ACID

The oriented chitosan films obtained from pre-sheared liquid crystalline chitosan/dichloroacetic acid (DCA)solutions were studied by means of polarized optical microscopy (POM), scanning electron microscopy (SEM), infra-reddichroism technique and wide angle X-ray diffraction (WAXD). The shear induced band texture in the film was found tocorrespond to the sinusoidal fibrillar microstructure along the shearing direction on the basis of POM and SEM observations.The sinusoidal fibril was found to be lying within the film plane. The model of chitosan molecular orientation in the pre-sheared film with band texture can be established assuming that the main chain orients in the shearing direction and the sidegroup is perpendicular to the shearing direction. The WAXD azimuthal scanning at 2θ= 20° indicates that the (002) planeorients perpendicular to the shearing direction.     

主链型液晶聚硅氧烷聚氨酯的合成及性质

合成了主链型联苯类及氧化偶氯苯类液晶聚硅氧烷聚氨酯弹性体，采用红外光谱，示差扫描量热，动态粘弹谱及带热台偏光显微镜等方法对聚合物进行了表征，讨论了它们的结构与性能．研究结果表明，这一系列多嵌段聚氨酯多数是向列型的液晶高分子聚合物，液晶相的形成同嵌段聚氨酯样品的软硬段相互作用有着密切的联系     

热致性液晶乙基纤维素和聚丙烯共混物的结构与性能

乙基纤维素（ＥＣ）和聚丙烯共混物沿取向方向有明显的絮条状结构，ＥＣ含量增加使Ｔｃ提高，△Ｈ和Ｔｍ有所降低，共混物的成核能力降低，结晶度下降，（１１０）晶面尺寸减小，（０４０）晶面尺增大。ＥＣ／ＰＰ共混物的ηａ、τａ值更接近于ＰＰ结果。力学测定结果给出，ＥＣ／ＰＰ＝１０／９０的共混物抗张模量有所增加。     

聚甲基丙烯酸-对-甲氧基偶氮苯烷氧基酯的合成及柔性间隔基对液晶行为的影响

通过甲基丙烯酸钾盐与溴化物的反应合成了一系列柔性间隔基长度不同的甲基丙烯酸 对 甲氧基偶氮苯烷氧基酯（ＰＭＡＡＺＯｎ,ｎ＝２,３,４,５,６）,然后聚合成相应的聚合物．用１Ｈ ＮＭＲ和ＩＲ表征了聚合物的结构,ＧＰＣ测定了分子量,ＤＳＣ和偏光显微镜观测了液晶高分子的相行为和织构．研究了间隔基长度对织构、相变和热力学性质的影响,观测到聚合物的ＴＮＩ随间隔基的长度变化表现出的奇偶效应．     

TRANSITIONS AND MODRPHOLOGY OF MAIN-CHAIN LIQUID CRYSTALLINE POLYMERS WITH X-SHAPED MESOGENS

The transitions and morphology of a series of main-chain liquid crystalline polymer with X-shaped mesogens were studied by means of DSC,SALS and polarizing microscopy techniques. Aneven-odd effect was observed for samples with different size of the substituents on the mesogenends. The isotropization process was similar to that of main-chain polymers with rod-likemesogens. No crystallization was detected for specimens cooling down from their isotropic meltstate. However two of the samples may crystallize in cooling process directly from the liquidcrystalline state.     

STUDY ON THE PHASE TRANSITION KINETICS OF THERMOTROPIC LIQUID CRYSTALLINE AROMATIC-ALIPHATIC COPOLYESTER

The phase transition kinetics of thennotropic liquid crystalline aromatic-aliphatic regular copolyester: were studied by DSC. By means of Kissinger's method the kinetic equation and parameters including activation energy, rate order and preexponential factor for phase transition from nematic to isotropic were obtained. The activation energy from crystal to nematic was also presented.     

酞侧基聚芳醚砜／对苯二甲酸乙二酯－对羟基苯甲酸嵌段共聚物共混物的研究

酞侧基聚芳醚砜／对苯二甲酸乙二酯－对羟基苯甲酸嵌段共聚物共混物的研究李刚，殷敬华，李滨耀（中国科学院长春应用化学研究所，长春，１３００２２）关键词酞侧基聚芳醚砜，热致性液晶高聚物，原位复合材料，对苯二甲酸乙二酯－对羟基苯甲酸嵌段共聚物将热塑性树脂与热...     

MELT BLENDS OF POLY (BUTYLEN TEREPHTHALATE) AND A THERMOTROPIC LIQUID CRYSTALLINE POLYMER

With the help of differential scanning calorimetry, cone-plate and capillary rheometry andscanning electron microscopy, a research has been conducted on rheological behavior,crystallization and morphology of poly (butylene terephthalate) (PBT) blends containing athermotropic LCP. The blend has zero entrance pressure loss, although the LCP has rather largeone. The viscosity curve of the blend lies between those of the LCP and PBT. The crystallizationof PBT is not affected by the presence of the LCP together with no indication oftransesterification between the two ingredients. LCP spheres and ellipsoids with the size of 0. 5--1. 5 μm disperse in PBT matrix uniformly, which is related to the viscosity ratio of the twocomponents.