液晶高分子材料纺制高强高模纤维

液晶高分子是近年来研究开发的一种新型高性能的高分子材料.液晶高分子可分为溶致液晶高分子及热致液晶高分子两大类.对于溶致性液晶高分子目前已有不少种类发展成为高性能纤维.溶致液晶高分子的代表是杜邦公司的芳香族聚酰胺(Kevlar),已于1972年进行工业化生产,目前生产能力已     

热致性液晶聚合物的纺丝

<正> 引言 液晶聚合物包括溶致性液晶和热致性液晶两种类型。热致性液晶聚合物的先驱性研究是由 Carborundum公司的Economy、Eastman     

聚芳酯液晶纤维的成形与热处理

介绍了热致液晶芳香族聚酯的合成方法,综述了聚酯液晶纤维的纺丝成形、热处理及工艺条件对纤维性能的影响,以及通过差示扫描量热仪、纤维强力仪等对聚芳酯液晶纤维与热处理后的纤维性能分析。     

低毒溶致液晶的构建及做姜黄素载体的研究

测定25℃条件下油烯基聚氧乙烯(20)醚在乙酸丁酯/水介质中的相图,探讨生物表面活性剂脱氧胆酸钠(NaDC)对体系相行为和流变性质的影响。进一步对上述体系所形成的溶致液晶进行对姜黄素的保护和体外释放研究。结果表明:体系中存在六角相和立方相,加入NaDC后六角相缩小,立方相消失。这些溶致液晶相在稳态剪切条件下均表现为剪切稀释的性质;但立方状液晶表现出较突出的弹性性质,表现在tanδ<0.1,而六角状液晶表现典型的黏弹性性质(tanδ为0.47～0.54),而且加入NaDC使六角状液晶的特征松弛时间增大。在光照下溶致液晶对姜黄素有保护作用,加入NaDC可使保护作用增强。这些液晶相对姜黄素有一定的缓释效果,NaDC的加入延长了其释放到达平衡所需要的时间,增强缓释效果。     

液晶高分子和聚丙烯的共混纤维(Ⅲ):纤维的物理机械性能

介绍了把液晶高分子与聚丙烯共混后在不同加工条件下得到的纤维的物理性能。结果表明:由于液晶高分子在纺丝成形后即具有很高的强度和模量,聚丙烯和液晶高分子共混纤维的初始模量比纯聚丙烯纤维有较大的提高;在牵伸过程中由于液晶高分子微纤维的断裂而使共混纤维的强度低于纯聚丙烯纤维;采用二级牵伸可显著改善共混纤维的物理机械性能,二级牵伸后的液晶高分子和聚丙烯共混纤维有很好的热稳定性。     

制备溶致液晶模板分离纯化孔雀草脂溶性类胡萝卜素技术及其机理初探

制备溶致液晶模板对天然色素分子进行分离纯化是一种高收率、低成本、操作安全、适于天然色素工业化生产的新型分离纯化技术.本文论述了通过制备孔雀草脂溶性类胡萝卜素溶致液晶模板,分离纯化该色素的技术方法,同时还分析并提出了制备溶致液晶模板对天然色素分子进行分离纯化的机理假设-化学反应模板理论.     

可连续化生产的电刺激响应型液晶纤维制备及其性能

为解决电刺激响应液晶纤维在无外加电极下的柔性变色问题,提出一种同轴三明治结构的电致变色液晶纤维的制备方法。采用连续涂层法制备以导电纤维为内导电层,导电水凝胶为外透明导电层,聚合物分散液晶为电致变色层的电刺激响应液晶纤维。对导电纤维种类、聚合物分散液晶体系组分等对电刺激响应液晶纤维形貌和电致变色性能的影响规律进行分析。结果表明:以炭黑掺杂锦纶为芯材的导电纤维,当胆甾相液晶、聚甲基丙烯酸甲酯、二氯甲烷质量比为15∶1∶8时,制备的电致变色液晶纤维有明显的3层核壳结构,具有良好的电致变色性能,其驱动电压为40 V,响应时间为9 s。所制备的无外加电极下电刺激响应液晶纤维器件可为纺织品智能柔性显示应用提供技术支持。     

壳聚糖溶致液晶性的研究

将壳聚糖溶于体积分数36%的乙酸溶液中浇涛制膜,在干燥下壳聚糖质量分数达到一定的临界质量分数形成溶致液晶.利用FTIR仪、原子力显微镜和X 射线衍射仪为表征手段,研究了壳聚糖溶致液晶相转变过程中分子间的相互作用以及液晶相微观结构的变化.结果表明,在该薄膜中有被冻结的液晶滴状结构,随着溶剂的挥发,膜体系内氢键的种类和数目发生改变,壳聚糖胶束颗粒聚集成圆盘或六角状,体现为同心环堆积,一定时间后转变为立方环状结构.这种液晶结构是壳聚糖胶束颗粒在分子间的相互作用下形成的自组装构型,是一种非平衡状态下的耗散结构.     

液晶高分子和聚丙烯的共混纤维（Ⅰ）：纤维结构的形成

介绍了共混纺丝的基本原理和方法 ,分析了在液晶高分子和聚丙烯共混纤维的纺丝过程中液晶相结构的形成过程。结果显示在采用液晶高分子强化聚丙烯纤维的过程中 ,液晶相的浓度、粘度、熔体的剪切和拉伸张力、喷丝头形状、相容剂等因素对液晶相结构的形成有很大的影响。在较高的浓度和较大的拉伸张力作用下 ,液晶高分子可以在聚丙烯纤维内形成具有强化作用的微纤维。     

液晶高分子和聚丙烯的共混纤维(I): 纤维结构的形成

介绍了共混纺丝的基本原理和方法,分析了在液晶高分子和聚丙烯共混纤维的纺丝过程中液晶相结构的形成过程.结果显示在采用液晶高分子强化聚丙烯纤维的过程中,液晶相的浓度、粘度、熔体的剪切和拉伸张力、喷丝头形状、相容剂等因素对液晶相结构的形成有很大的影响.在较高的浓度和较大的拉伸张力作用下,液晶高分子可以在聚丙烯纤维内形成具有强化作用的微纤维.     

液晶高分子和聚丙烯的共混纤维(Ⅱ):纤维的牵伸性能

 在液晶高分子和聚丙烯的共混纤维中,液晶高分子以细而长的微纤维对聚丙烯起到强化作用。通过对初生纤维进行牵伸可以提高共混纤维中聚丙烯的取向度。故对牵伸过程中液晶微纤的受力状况以及影响牵伸后液晶微纤长度的各种因素进行了分析。     

基于对羟基苯丙酸的生物基液晶共聚酯纤维的合成与性能

针对常规生物基纤维力学性能与耐热性不足的问题,以6-羟基-2-萘甲酸、对羟基苯甲酸和对羟基苯丙酸(HPPA)为原料,采用一锅熔融聚合法合成了生物基液晶共聚酯,并通过熔融纺丝制备得到初生纤维,对共聚酯及其初生纤维的结构与性能进行研究.结果表明:制备得到的生物基液晶共聚酯为向列型液晶,其熔点在200℃左右,并随着HPPA添...     

异甘露醇桥接的苯并菲盘状液晶二聚体的性能研究

液晶二聚体因既具有液晶单分子排列的有序性又具有高分子液晶的成膜性,成为液晶领域研究的热点之一。本实验以异甘露醇为手性桥接链,以2-羟基-3,6,7,10,11-五戊氧基苯并菲为液晶基元,合成了一种新型的手性盘状液晶二聚体M5C,通过核磁共振氢谱、傅立叶红外光谱等手段确认了其化学结构;采用圆二色光谱仪测定化合物在室温下的旋光性,表明该化合物是左旋光性的;采用热重分析、差示扫描量热法、热台偏光显微镜、X射线衍射仪对其进行了液晶性能的研究,结果表明该化合物为互变型热致液晶,且在液晶温度范围内呈六方柱状相。     

高强度聚偏氟乙烯纤维的熔融纺丝法制备

为得到高拉伸强度的聚偏氟乙烯(PVDF)纤维,通过正交实验和单因素实验,研究了熔融纺丝法制备PVDF纤维的工艺条件,并利用热分析(DSC)、红外光谱法(FT-IR)、X射线衍射(XRD)和拉伸试验研究了纤维的晶体结构、晶区取向和力学性能。研究结果表明：纺丝过程中影响纤维拉伸强度的因素主次顺序为卷绕速率>喷头温度>喷嘴直径>入水距离,最优条件为卷绕速率10.2 m/min,喷头温度240 °C,喷嘴直径2.0 mm,入水距离40 cm;初生纤维既含有α晶型,也有β晶型,冷拉伸使得纤维发生α→β晶型转变,总体结晶度和取向度均有提高,拉伸强度明显提高,并在最大拉伸倍数6.5倍左右达到最大值591 MPa。     

液晶态分离提纯大豆磷脂的研究

水化油脚中的大豆磷脂在一定条件下可以转变成液晶状态。液晶态大豆磷脂具有良好的流动性和较高的纯度,与水化油脚中的其它物质,如油脂和其它杂质等易于分离。液晶态大豆磷脂(干基)的丙酮不溶物(AI值)高达85%,可以粉碎成颗粒。这种颗粒磷脂非常适合超临界二氧化碳流体萃取技术对物料的要求,从而为超临界二氧化碳流体萃取技术生产AI值超过95%颗粒磷脂的工业化构建了必要的技术平台。本研究不仅可以避免现行的丙酮萃取脱油技术所带来的环境和产品污染,而且还可以降低生产成本。     

Formation of Lipid Emulsions and Clear Gels by Liquid Crystal Emulsification

Recently developed emulsion technologies for the formation of fine emulsions, lipid emulsions and clear gels by liquid crystal emulsification were reviewed. As a basic information on liquid crystal emulsification, the structures and characteristic behaviours of lyotropic liquid crystals were summarized. Formation of a liquid crystalline phase was often seen in emulsions and biological systems. The significance of liquid crystal formation during emulsification was analysed by comparing the states and stabilities of emulsions prepared by different processes. Then uses of liquid crystals for formation of the characteristic emulsions and gels were also discussed. In liquid crystal emulsification, an oil phase is dispersed directly into the lamellar liquid‐crystalline phase composed of surfactant, glycerol and water to prepare a gel‐like oil‐in‐liquid crystal emulsion. This is followed by dilution with the remaining water to produce an emulsion. From the phase behaviour during emulsification and analysis of the local motion of the liquid crystal membrane by fluorometry, it was confirmed that the interaction between surfactant and a polyol molecule such as glycerol promotes hydrogen bonding and enhances the strength of the lamellar liquid crystal membranes, which results in the formation of oil‐in‐liquid crystal emulsions. The interaction between the liquid crystal and oil was analysed from the changes in molecular motion of the membrane at the oil‐liquid crystal interface using the spin label technique of electron spin resonance (ESR). The fluidity of the liquid crystal membrane did not change when oil was added, and therefore oil‐in‐liquid crystal emulsions of various oils were prepared by the identical process. This lack of dependence of the liquid crystal membrane on oil results in the unique properties of liquid crystal emulsification, which can be used for oils of various polarity and different molecular constituents. When a self‐organizing artificial stratum corneum lipid containing pseudo‐ceramide was used as a principal component of the oil, a multilamellar emulsion of concentric lamellar structure was formed. The multilamellar emulsion supplements the physiological function of stratum corneum by the identical mechanism as natural intercellular lipids. High‐pressure treatment of the lipid emulsion produced a gel‐like emulsion crystal, in which the homogeneous nanoemulsion droplets were arranged in a hexagonal array. This review paper was presented at the Conference of the Asian Societies of Cosmetic Scientists 2005 in Bangkok.     

Preparation and physical properties of maltodextrin stearates of low to high degree of substitution

Maltodextrin stearates of degree of substitution (DS) 0.07–2.40 were prepared by heating dry maltodextrin and vinyl stearate in the ionic liquid BMIM dca at 75°C. Stearates of low DS (0.07) were insoluble in water but formed a gel and absorbed over seven times their weight of water. Stearates with high DS (2.4) were soluble in chloroform or toluene and had a high degree of swelling in hydrocarbons such as hexane. Films cast from maltodextrin stearates had water contact angles of 84–93°, indicating a very hydrophobic surface. X‐ray diffraction and DSC of DS >0.6 indicated some short‐range crystallization of the stearate side chains. Optical birefringence was noted at moderate to high DS, suggesting liquid crystal formation. Maltodextrin stearates of DS ∼0.6 showed intense birefringence resembling starch granules in DMSO while cholesteric liquid crystalline behavior was observed in toluene (reflected blue light). Blue light reflection disappeared on heating to >60–80°C then reformed on cooling. These results suggest that starch stearates have some interesting structural ordering and have potential applications as water absorbents, hydrocarbon/oil absorbents, water resistant coatings, and liquid crystalline materials.