芳纶的加工与应用

本文对芳纶加工的液晶态加工的条件作了一个理论的简述,对芳纶的加工类型提出一种分级的方法,并通过这种方法对芳纶的加工及应用进行描述及分析.     

芳纶纤维的合成方法及纺丝工艺的研究进展

介绍了合成对位芳纶的几种主要方法,包括界面缩聚法、直接缩聚法、低温溶液缩聚法、酯交换法、气相合成法等.对已工业化的芳纶纤维,详细论述了其反应原理、合成步骤和影响因素.详细论述了芳纶纤维成纤的一步法工艺、两步法工艺及芳纶浆粕纤维的制备方法.     

芳纶技术的发展及应用

芳纶是一种有机合成的、高技术含量和高附加值的高性能特种纤维,目前工业化的品种主要有两大类:芳纶l414(对位芳纶)和芳纶1313(间位芳纶),该文简单地介绍了两种芳纶纤维国内外的发展状况,着重介绍了它们的制备方法、性能和在各个领域的应用,并对目前国内芳纶存在的问题做了简要分析。     

芳纶纤维的合成及化学改性研究新进展

芳纶纤维的合成及化学改性是当今的研究热点,本文介绍了芳纶纤维在备领域的应用及其优异性能,详细介绍了芳纶纤维的发展现状,简要介绍了不同的结构形态的芳纶纤维,比较了芳纶纤维的各种化学改性方法,并我国芳纶纤维的工业发展前景做出了展望.     

芳纶纤维增强复合材料的机械加工实例研究

在复合材料应用范围不断拓展的背景下,对复合材料加工性能提出了更高的要求。而芳纶纤维复合材料的应用,有望加强复合材料加工性能。因此,以芳纶纤维性质为切入点,阐述了芳纶纤维材料缺陷,分析了芳纶纤维增强复合材料优势,并以医疗床板中芳纶纤维增强复合材料加工为例,对芳纶纤维在增强玻璃布及树脂的机械加工性能进行了分析。     

对位芳纶的合成及纺丝工艺研究进展

介绍了合成对位芳纶的界面缩聚法、直接缩聚法、低温溶液缩聚法、酯交换法、气相合成法等主要方法。详细论述了已工业化的对位芳纶成纤方法如：一步法工艺、两步法工艺及其芳纶浆粕纤维的制备方法,指出生产对位芳纶采用低温溶液缩聚法的合成、原液纺丝法纺丝的工艺,是我国对位芳纶实现工业化的合适路线。     

芳纶浆粕纤维对CR基质补强特性的研究

对比研究未处理芳纶浆粕和芳纶浆粕预分散体以及不同品种芳纶浆粕纤维补强CR复合材料的微观结构形态及芳纶浆粕纤维对CR基质的补强特性。结果表明,芳纶浆粕对基质橡胶补强潜力的发挥取决于超细纤维在基质橡胶中的分散均匀性、伸展性和取向性,芳纶浆粕纤维对基质橡胶在常温和高温下都具有很高的模量补强效率。     

高性能芳纶市场开发前景广阔

高性能芳纶纤维是一种高强度、高模量、耐磨性好的高科技纤维，由于其良好的应用性能，全球市场对芳纶的需求呈不继增加的态势，芳纶纤维已进入快速发展的时期，在芳纶纤维生产领域，对位芳纶发展最快，对位芳纶的主要品种为芳纶1414，其化学名称为聚对苯二甲酰对苯二胺（PPTA）。目前国内PPTA合成技术不断成熟，工业化生产已开始起，随着未来产能不断扩大，国内PPTA开发前景广阔。     

俄罗斯芳纶发展概况及其制备、性能与应用

对俄罗斯芳纶做了全面的综述,详细介绍了其间位芳纶、对位芳纶和杂环芳纶的发展概况、化学结构、性能及应用等,重点介绍了对位杂环芳纶SVM、Armos和Rusar的发展及应用情况,最后展望了杂环芳纶的应用前景。     

高性能芳纶及其中间体开发前景广阔

高性能芳纶纤维是一种高强度、高模量、低度耐磨性好的高科技纤维,由于其良好的应用性能,球市场对芳纶的需求呈不断增长的态势,芳纶纤己进入快速发展期,在芳纶纤维生产领域,对位芳发展最快,对位芳纶主要品种为芳纶1414,其化名称为聚对苯二甲酰对苯二胺（PPTA）。目前国PPTA合成技术不断成熟,工业化生产已经开始步,随着未来产能不断扩大,国内PPTA及其所需的主要中间体开发前景广阔。     

Bright structural colorful aramid fabrics with outstanding light fastness

The problems of difficult dyeing, poor dyeing fastness, and dyeing pollution of aramid are always great obstacles in the practical application. In theory, constructing particular nanostructures instead of dyes on aramids to achieve bright structural colors will be an effective strategy. However, it is still challenging to construct particular nanostructures on aramid fabric surfaces because of their roughness. Here, beautiful and noniridescent structural colored aramids with excellent light fastness were achieved by spraying a thin layer of randomly distributed nanospheres on the surface of adhesive-modified aramids. Moreover, different bright structural colors and colorful patterns were obtained by simply controlling the size or refractive index of the spheres. Importantly, the light fastness of the structural colored aramid can reach levels 6–7 or higher. The simple and eco-friendly coloring technology can be compatible with industrial equipment to obtain stable multicolored aramid products, exhibiting great real potential applications.     

The dilaton approach to evaluating the limiting mechanical properties of aramid fibres in high-speed pulsed loads

The dilaton mechanism can be used to estimate the real lifetime of aramids in conditions of pulsed loads. The dependence of the power time parameters makes it possible to characterize the performance properties of aramids of the Rusar type. __________ Translated from Khimicheskie Volokna, No. 6, pp. 9–12, November–December, 2006.     

Developments in oriented polymers, 1970–2004

Abstract

The discovery of methods to make highly oriented polymers has given tremendous stimulus to both basic polymer science and industrial developments in the period 1970 to the present. High modulus, high strength fibres for aramids and polyethylene, are based on very different methodologies but the ultimate result is similar in producing fully extended polymer chains. For polymers in solid sections, the enhancement of properties is less dramatic but still very worthwhile. In this case, three methods are described: hydrostatic extrusion, die-drawing and hot compaction of oriented fibres and tapes. Hot compaction is a new technique with many possibilities for which a wide range of applications has already been identified.     

Direct synthesis and melt‐drawing property of aramids by bulk polycondensation of isophthalic acid with m‐phenylenediamine and 3,4′‐oxydianiline

The direct polycondensation of isophthalic acid with a mixture of 1,3‐phenylenediamine (m‐PDA) and 3,4′‐diaminodiphenyl ether (3,4′‐ODA) could be successfully performed in the bulk to afford the expected co‐aramids for the first time. The co‐aramids with low molecular weights and 3,4′‐ODA contents higher than 50 mol% display excellent thermoplasticity and melt‐drawing property. Indeed, several meters long filaments with 12 μm diameter could be produced. In addition, the environmentally friendly method for the preparation of aramid materials as well as the demonstration of their filament formation will open up the new possibility to prepare aramid fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Amide-containing segmented copolymers

This review highlights the synthesis, physical properties, and emerging technologies of state-of-the-art segmented copolymers containing amide hydrogen bonding sites. Amide hydrogen bonding plays a crucial role in the physical properties associated with amide-containing segmented copolymers. Amide hard segments are accessible in many different forms from amorphous alkyl amides to crystalline aramids and greatly influence copolymer morphology and mechanical properties. Variations in copolymer structure allow for the fine tuning of physical properties and the ability to predict mechanical performance based upon structural modifications. This review includes various synthetic methods for producing well-defined amide-containing segmented copolymers as well as common applications. Also, the morphological and mechanical properties associated with modifications in copolymer structure are discussed.     

Preparation and characterisation of blends based on polyamide 6 and hyperbranched aramids as palladium nanoparticle supports

Solution and melt blends have been prepared by mixing polyamide 6 (PA6) with hyperbranched (HB) aromatic polyamides (aramids) synthesized from A₂ (p-phenylenediamine)+B₃ (trimesic acid) reactants. The HB aramids (pPDT), were obtained using various polymerization conditions, hence were characterized by different content and ratio of -COOH and -NH₂ end group functionalities, as well as different architectures.For comparison, the characteristics of the above blends have been matched to those based on PA6 and the HB aramid synthesised from an AB₂ monomer (namely 5-(4-aminobenzoylamino)isophthalic acid, named ABZAIA), which was the topic of a previous paper of ours [O. Monticelli, D. Oliva, S. Russo, C. Clausnitzer, P. Pötschke, B. Voit, Macromol Mater Eng 288 (2003) 318-25. [1]]. Viscosity data and glass transition temperatures of solution and melt blends underlined the good miscibility between the blend components. Blend properties, namely glass transition temperature and rheological behaviour, have been found to depend on concentration and type of the HB aramid. Indeed, the presence of pPDT aramids in the blends caused a weaker variation of the rheological behaviour, with respect to neat PA6, as compared to poly(ABZAIA).Both the above solution and melt blends have been used as supports of palladium nanoparticles. The metal-retaining capability of neat PA6 was greatly enhanced by blending it with pPDT polymers. In these blends, the Pd loading has been found directly proportional to the amino group content of the HB aramid, thus justifying better performances of pPDTs over poly(ABZAIA). The large increase of metal loading in the above blends has not been carried out at expenses of Pd nanoparticle dimensions, as revealed by the unchanged size distribution of metal dispersion by TEM.     

Facile preparation and characterization of soluble aramid

It remains a problem to prepare cost‐effective aramid with good solubility via a simple method since the commercialization of aromatic polyamides such as Kevlar and Nomex by DuPont in 1960s. Herein, we report the facile preparation and properties of an aromatic polyamide copolymerized by 2,6‐naphthalene dichloride (26N‐COCl), 4,4′‐oxydianiline, and m‐phenylenediamine. The synthetic route is very facile and cost‐effective. The modified aramids possess excellent comprehensive properties. The polymers are soluble in some organics. Their thermal stabilities are excellent, with 5% weight loss temperatures (T_d,5%'s) in air higher than 460 °C and glass transition temperatures (T_g's) higher than 280 °C. These polymers are easily processed into films, fibers, and tubes. The products exhibit high strength. For example, the films have excellent mechanical strength, with a tensile strength up to 139 MPa, a tensile modulus up to 3.45 GPa, and an elongation of 11%. The films are also transparent and fluorescent. The overall properties are better than those of the commercial Nomex. The facilely prepared aramids with good solubility are very promising for commercial use. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46341.     

Synthesis and characterization of novel aromatic polyamides derived from 2,2′‐bis(p‐phenoxyphenyl)‐4, 4′‐diaminodiphenyl ether

BACKGROUND: Wholly aromatic polyamides (aramids) are high‐performance polymeric materials with outstanding heat resistance and excellent chemical stabilities due to chain stiffness and intermolecular hydrogen bonding of amide groups. Synthesis of structurally well‐designed monomers is an effective strategy to prepare modified forms of these aramids to overcome lack of organo‐solubility and processability limitations. RESULTS: A novel class of wholly aromatic polyamides was prepared from a new diamine, namely 2,2′‐bis(p‐phenoxyphenyl)‐4,4′‐diaminodiphenyl ether (PPAPE), and two simple aromatic dicarboxylic acids. Two reference polyamides were also prepared by reacting 4,4′‐diaminodiphenyl ether with the same comonomers under similar conditions. M?_w and M?_n of the resultant polymers were 8.0 × 10⁴ and 5.5 × 10⁴ g mol^?1, respectively. Polymers resulting from PPAPE exhibited a nearly amorphous nature. These polyamides exhibited excellent organo‐solubility in a variety of polar solvents and possessed glass transition temperatures up to 200 °C. The 10% weight loss temperatures of these polymers were found to be up to 500 °C under a nitrogen atmosphere. The polymers obtained from PPAPE could be cast into transparent and flexible films from N,N‐dimethylacetamide solution. CONCLUSION: The results obtained show that the new PPAPE diamine can be considered as a good monomer to enhance the processability of its resultant aromatic polyamides while maintaining their high thermal stability. The observed characteristics of the polyamides obtained make them promising high‐performance polymeric materials. Copyright © 2009 Society of Chemical Industry     

Mechanical properties of epoxies reinforced with chloride-treated aramid fibers

Surface treatment of aramid fibers by immersion in a solution of methacryloyl chloride in carbon tetrachloride was carried out, and the resulting material was examined by means of electron microscopy and chemical analysis in an attempt to record any changes in the morphology and nature of the surface. Mechanical testing of tensile, flexural, and interlaminar shear strength, as well as dynamic mechanical analysis (DMA), were performed in an attempt to explore the effect of this treatment on the strength of the fiber. In a subsequent stage, the performance of those fibers as reinforcement in composites of epoxy matrix was assessed. The aim of this study was to provide more information about the interactions between the chloride-treated aramid fibers and the epoxy resin and, more specifically, to compare the behavior of the epoxy matrix composites with those composed of unsaturated polyester, polyethylene, and polyurethane matrix, which were studied in the past. It was found that specimens containing chloride-treated aramids display better flexural properties, whereas their tensile strength is drastically reduced. Improved performance was also identified by the DMA experiments. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:–, 1997     

Synthesis and characterization of spider‐web‐like electrospun mats of meta‐aramid

The effect of salt formation during condensation polymerization on the morphology of electrospun meta‐aramid fibers was investigated. The presence of a by‐product salt (CaCl₂) improved the electrospinability of the meta‐aramid solution and induced the formation of a spider‐web‐like structure in the mat. The effect of the concentration of the solution and the applied voltage on the formation of the spider‐web‐like fibrous structure was investigated. Field emission scanning electron microscopy images indicated that thin fibers were uniformly distributed with thick fibers throughout the mats in the form of a spider‐web‐like structure. Thermogravimetric analysis showed that the thermal stability of the electrospun mat was affected by CaCl₂. The observed enhancement in the thermal and mechanical properties of the mats, which was attributed to the formation of the spider‐web‐like structure, may increase the number of potential applications of meta‐aramids, such as water/air filtration, protective clothing and electrical insulation. Copyright © 2012 Society of Chemical Industry