一种全芳香热致液晶聚芳醚酮

聚芳醚酮由于熔融粘度大和加工温度高而影响了其进一步工业化，因此降低熔融粘度和加工温度是研究聚芳醚酮的新课题[1]．目前在工程塑料中热致液晶高分子是一种具有低熔融粘度而性能优异的材料，其熔融粘度比一般高分子材料低得多，并且具有优异的机械性能[2]本文采用无现...     

聚酯醚液晶弹性体的相行为与力学性能

用热台偏光显微镜、差示扫描量热仪、广角Ｘ－射线衍射仪和单纤维电子强力仪对一类新型的聚酯醚液晶弹性体的相行为与力学性能进行了研究。讨论了共聚物性能同硬段含量的关系。研究表明这类嵌段共物由于产生微相分离而兼具橡胶弹性和热致液晶性,它们的拉伸强度为１０～４２ＭＰａ,弹性模量为５～３０ＭＰａ,断裂伸长率为２００～３２０％。     

Synthesis and properties of novel thermotropic liquid crystalline copoly(ester-imide)s

Four novel copoly(ester-imide)s based on 3,3',4,4'-biphenyltetracarboxylic dianhydride,bis(trimellitic acid anhydride) phenyl ester and di-p-aminophenyl ester of dicarboxylic acids were synthesized via two-step method in order to investigate whether two imide mesogenic units with different conformation and polarity could control the formation of LC-phase.Polarizes light microscopy(PLM) and differential scanning calorimetry(DSC) have shown that three polymers formed the nematic phase with thread schlieren...     

液晶聚芳醚酮的结构与性能研究

以联苯二酚、取代对苯二酚及含氟酮单体为原料 ,通过亲核取代反应 ,合成了系列具有液晶性的新型聚芳醚酮 .研究了聚合物分子结构与性能之间的关系 .由于结晶相是从有序的液晶相转化形成的 ,故侧基含量的增加对液晶聚合物的融熔转变温度无显著影响 .聚合物的液晶稳定性受侧基影响较大 ,含极性侧基的氯取代聚合物的液晶温区比含大空阻侧基的聚合物的液晶温区小得多 ,说明空间几何因素比极性因素对液晶稳定性的影响大 .不同分子量聚合物有不同的液晶有序结构 ,低分子量聚合物具有高有序液晶结构 ,而高分子量聚合物只有低有序的向列相结构 .     

热致液晶聚酯酰亚胺的非等温相转变动力学研究

以差示扫描量热法对热致液晶聚酯酰亚胺的结晶过程和液晶化过程的非等温相转变动力学行为进行了初步研究，根据Ｊｅｚｉｏｒｎｙ方法处理数据得到了表征聚合物非等温相转变动力参数Ｚｃ，Ｇｃ并对其进行了讨论，结果表明，在所研究的条件下聚合物的相转变过程基本上符事Ｊｅｚｉｏｒｎｙ结论，但两种相转变的成核与生长方式是不同的。     

Synthesis of Bis(4'-hydroxyphenyl)-toluene-2, 4-diurethane for Main Chain Liquid Crystalline Poly(urethane-ester)s

Intr0ducti0nLiquidcrystallinepoIyurethaneshaveattractedconsiderableinterestsinceIimura1andhiscoworkersobtainedtheminl98l.M0stofthep0lyurethanesthathaveappearedinliteraturewerebasedonasinglemes0gen(diisocyanateordiol),whichhadbeenreactedwith0nec0unterpart(di0l0rdiisocyanate)togiveap0lyurethane.Inprevi0usinvestigations'-',compoundsusedasmesogensallhadcompletemesogeniccores,whethertheyhadliquidcrystalpropertiesornot.Thisimpliesthatthemes0geniccoresexistedbeforetheformationoftheurethanegroupsorth…     

LC-polyimides XXXIV. Noncrystalline thermotropic copoly(ester-imide)s based on PET

Four series of copoly(ester-imide)s (co-PEIs) were prepared by transesterification of poly(ethylene terephthalate), PET, with N-(4-carboxyphenyl)trimellitimide and an acetylated diphenol. Methylhydroquinone, tert. butylhydroquinone, phenylhydroquinone, and 2,7-dihydroxynaphthalene were used as diphenols. The chemical structures of these co-PEIs were characterized by chemical analyses, ¹H-, and ¹³C-NMR spectra. A low degree of crystallinity was observed when the PET content was above 85% mol %. Between 60 and 80 mol % PET all co-PEIs are biphasic, whereas below 60 mol % the co-PEIs form a homogeneous nematic melt and below the glass transition temperature (T_g) a nematic glass. The T_gs vary continously with the molar composition but the mechanical properties drop sharply when the nematic phase changes to an isotropic one. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1813–1820, 1998     

Unsaturated poly(ester-imide)s from hydroxy-terminated polybutadiene, dianhydride and diisocyanate

Hydroxy terminated polybutadiene has been used for the first time in the synthesis of poly(ester-imide)s [P(E-I)s]. Anhydride terminated polyester prepolymers were prepared by the reaction of two different polyols--polytetramethyleneoxide glycol (PTMG) of molecular weight 1000 and hydroxy terminated polybutadiene (HTPB) of molecular weight 2500--and different dianhydrides--pyromellitic dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA) and 4,4^′-(hexafluoroiso-propylidene)diphthalic anhydride (HFDA). The prepolymers were then reacted with different diisocyanates--80:20 mixture of 2,4- and 2,6-tolylene diisocyanate (TDI), 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and 4,4^′-methylene bis(phenylisocyanate) (MDI) resulting in P(E-I)s. The P(E-I)s were characterised by FT-IR, FT-NMR, GPC, TGA, DSC and for static and dynamic mechanical properties. The polymers based on PTMG showed two distinct melting points and behave as thermoplastic elastomers. The thermal stability and mechanical properties of P(E-I)s based on HTPB were substantially higher than those based on PTMG.     

Synthesis and properties of novel aromatic poly(ester-imide)s bearing 1,5-bis(benzoyloxy)naphthalene units

Two series of new aromatic poly(ester-imide)s were prepared from 1,5-bis(4-aminobenzoyloxy)naphthalene (p-1) and 1,5-bis(3-aminobenzoyloxy)naphthalene (m-1), respectively, with six commercially available aromatic tetracarboxylic dianhydrides via a conventional two-stage synthesis that included ring-opening polyaddition to give poly(amic acid)s followed by chemical imidization to polyimides. The intermediate poly(amic acid)s obtained in the first stage had inherent viscosities of 0.41-0.84 and 0.66-1.37 dl/g, respectively. All the para-series and most of the meta-series poly(ester-imide)s were semicrystalline and showed less solubility. Two of the meta-series poly(ester-imide)s derived from less rigid dianhydrides were amorphous and readily soluble in polar aprotic solvents, and they could be solution-cast into transparent and tough films with good mechanical properties. The meta-series polymers derived from rigid dianhydrides were generally semicrystalline and showed less solubility. Except for one example, the meta-series poly(ester-imide)s displayed discernible T_gs in the range 239-273 °C by DSC. All of these two series poly(ester-imide)s did not show significant decomposition below 450 °C in nitrogen or in air.     

Synthesis and Characterization of Thermotropic Liquid Crystalline Polyesters

Abstract

Synthesis and characterization of polyesters of 4,4′-dihydroxy biphenyl with succinic, adipic, suberic and sebacic acids were carried out. Initially the diacids were converted to the corresponding acid chlorides in dimethyl formamide (DMF). 4,4′-dihydroxy biphenyl was prepared from 4-hydroxy biphenyl by bromination and subsequent hydrolysis. The low molecular weight polyesters were prepared by the condensation of diacid chlorides with 4,4′-dihydroxy biphenyl in DMF at appropriate temperature. All the polymers were characterized by ¹H NMR, FT-IR, DSC and hot stage polarizing microscope. Thermotropic liquid crystalline behaviour was established by high temperature X-ray (HTXRD) at various temperature intervals. It was found that among the four compounds prepared, three of them showed nematic phase liquid crystallinity with the exception of the ester of succinic acid.     

PET-HBT嵌段热致性液晶共聚酯的合成

液晶高分子材料具有相当高的强度和模量，被誉为当代超级工程塑料．以对羟基苯甲酸甲酯、1，4-丁二醇为主要原料，经熔融酯交换合成双-对羟基苯甲酸丁二醇酯(BBHB)；以四氯乙烷为溶剂，采用溶液缩聚法将过量的BBHB与对苯二甲酰氯(TPC)合成端基为BBHB的齐聚物(PHBT)；以对苯二甲酸二甲酯与乙二醇为原料，经熔融酯交换合成对苯二甲酸双β-羟乙酯(BHET)，然后采用溶液缩聚法将BHET与少量的TPC合成端基为TPC的齐聚物(PTET)；最后以PHBT与PTET为原料，以四氯乙烷为溶剂，采用溶液缩聚法合成目标共聚酯(PET-HBT)。研究了共聚酯的双折射现象及热行为；用偏光显微镜观察了试共聚酯的织态结构并用FTIR表征了共聚酯的微观结构．     

Dielectric relaxation of LC-thermotropic poly(ester imide)s

Two different series of poly(ester imide)s, which are distinguished from each other in the orientation of the ester linkages and show well-differentiated thermotropic behavior, are investigated by means of model calculations and dielectric relaxation spectroscopy. Model calculations show that the orientation of the ester linkages has a strong influence on the rotational energy barriers. The dielectric relaxation spectra of both series shows three relaxation regions in the temperature range between 100 and 400 K that have been identified as the α-, β- and γ-relaxation processes. A difference of about two orders of magnitude between the characteristic rates of the γ-relaxation is the main feature observed in the dielectric response. However, the β-relaxation shows very similar behavior for both series. The differences in the relaxation behavior in the solid state are interpreted on the basis of the rotational barriers deduced from the model calculation results. © 1997 John Wiley & Sons, Inc.     

热塑性聚酯醚液晶弹性体的合成与表征

液晶聚酯醚嵌段共聚物是一类新型的高分子材料,已有较多研究［１～３］．当共聚物中软、硬段比例适当,在一定温度范围内,这类液晶聚合物可能出现高弹性．但系统报道聚酯醚液晶弹性体的工作并不多．Ｌｅｎｚ［２］报道得到了类似橡胶的低强度、低模量和高伸长率的液晶弹...     

LC polyimides. XXVII. Cholesteric poly(ester-imide)s derived from chiral i-pentyloxyterephthalic acids

(S)-Pentyloxyterephthalic acid was prepared by alkylation of dimethyl trimethylsiloxyterephthalate with (S)-2-methylbutan-1-ol tosylate. (S,S)-2,5-bis-i-pentyloxyterephthalic acid was prepared analogously by alkylation of diethyl-2,5-bis(trimethylsiloxy)terephthalate. A series of cholesteric poly(ester-imide)s was synthesized from (S)-pentyloxyterephthalic acid and N-(4'-hydroxyphenyl)-4-hydroxyphthalimide. 2-(4'-Chlorophenoxy)terephthalic acid was used as comonomer. The 1 : 1 copolyester of both terephthalic acids forms a Grandjean texture in the shearing of the cholesteric melt. A second series of cholesteric poly(ester-imide)s was prepared from (S,S)-2,5-bispentyloxyterephthalic acid and the aforementioned imide diphenol. In this case 2,5-bis(dodecyloxy)terephthalic acid was used as comonomer to lower the melting point. The cholesteric phases of the resulting copoly(ester-imide)s did not form a Grandjean texture. © 1996 John Wiley & Sons, Inc.     

Thermal Properties and Crystallinity of Thermotropic Liquid Crystalline Copolyesters Prepared from Poly(ethylene terephtalate) (PET) and Rigid Aromatic Units

A series of copolyesters were synthesized by melt‐polycondensation reaction of poly(ethylene terephtalate) (PET) with various proportions of equimolar compositions of p‐acetoxybenzoic acid (p‐ABA), hydroquinone diacetate (HQDA) and terephtalic acid (TPA). Viscosity, liquid crystallinity, thermal properties, degree of crystallinity and thermal stabilitiy of these copolyesters were investigated by Ubbelohde viscometer, hot‐stage polarized light microscopy (PLM), differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD) and thermogravimetric analysis (TGA), respectively. On the basis of viscosity measurement, it was observed that intrinsic viscosity values of the copolyesters are increased regularly with increasing amounts of aromatic units (p‐ABA, HQDA and TPA) in the polymer chain. Thermotropic liquid crystalline behavior was observed in the copolyesters containing over 50 mol% of rigid p‐ABA/HQDA/TPA aromatic units. DSC analysis of the anisotropic copolyesters revealed broad and weak endotherms associated with the nematic phases, and the melting temperatures were found to be in the processable region. As the mol% of PET in the polymer chain increased, the specific enthalpies of fusion and the degree of crystallinity of the copolyesters were also increased regularly.     

The Rheological and Extrusion Behaviour of Blends Based on Phenolphthalein Poly(ether-ether-sulfone) and Thermotropic Liquid Crystalline Polymer

ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｔｈｅｌａｓｔｔｗｏｄｅｃａｄｅｓ，ｐａｒｔｉｃｕｌａｒａｔｅｎｔｉｏｎｈａｓｂｅｅｎｄｅｖｏｔｅｄｔｏｕｓｉｎｇｔｈｅｔｈｅｒｍｏｔｒｏｐｉｃｌｉｑｕｉｄｃｒｙｓｔａｌｉｎｅｐｏｌｙｍｅｒｓ（ＴＬＣＰ）ａｓａｒｅｉｎｆｏ...     

一种新型聚芳醚酮的热致液晶行为

聚芳醚酮具有优异的耐热性和环境稳定性 ,作为特种工程塑料在宇航、军工等高技术领域得到了广泛的应用 [1 ] .但其熔融温度较高 ,熔体粘度较大 ,在加工中存在一定困难 .热致液晶高分子 ( TLCP)具有较低的粘度 ,复合在热塑性高分子基体中的 TL CP在剪切力或拉伸应变流的作用下发生取向、变形成纤 ,其强度比热塑性基体高 1～ 2个数量级 ,另外 TL CP微纤提供了极大的纤维粘附表面积 ,因此 ,TL CP与聚合物共混具有广阔应用前景 .本文通过联苯二酚、 2 -叔丁基 - 1 ,4-对苯二酚与 4,4′-二氟二苯酮的亲核取代反应合成了一种具有热致液晶性…     

胆甾型侧链液晶共聚物的研究

合成并表征了两个胆甾型液晶烯类单位以及它们分别与辛烯－１，二氧化硫进行自由基共聚合得到的一系列不同组成的胆甾型侧链液晶三元共聚砜。研究结果表明：该共聚砜的两个液晶热转变温度均随其中辛烯－１单体单元组份含量的增加而降低。