Introduction of fluorin into PBO polymer chains: Toward higher thermal stability and lower dielectric constant

A series of novel fluorinated benzoxazole polymers (6FPBO's) with high thermal stability and low dielectric constant were synthesized by copolymerization of 1,3-diamino-4, 6-dihydroxybenzene dihy-drochloride (DAR), 1,4-benzenedicarboxylic acid (PTA) and various amount of 4'4- (hexafluoroisopro-pylidene) bis (benzoic acid) (BIS-B-AF) in the medium of polyphosphoric acid (PPA). 6FPBO fibers were then obtained via dry-jet wet-spinning technique and characterized by means of Fourier transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), single fiber tensile testing machine and scanning electron microscopy (SEM). FTIR spectrum of 6FPBO fibers indicated that the fluorine groups had been incorporated into PBO molecular chains successfully. TGA curves revealed that 6FPBO fibers possessed high thermal stability just as pure PBO fibers. Moreover, dielectric constant spectrum of 6FPBO exhibited that the polymers had low dielectric constant, especially in the range of high- frequency.     

Surface Modification of Reinforcement Fibers for Composites by Acid Treatments

In this study, we investigated the surface modification of reinforcement fibers for composites by acid treatments, including PBO fiber, Kevlar fiber and carbon fiber. The corresponding changes in the surface free energy components were carefully evaluated using a Cahn dynamic contact angle analysis system. In addition, the fiber's surface elemental composition and topography were studied using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The results showed that the surface nitrogen-to-carbon (N/C) and oxygen-to-carbon (O/C) ratios were significantly increased after the treatments. The surface free energy of PBO fiber was increased from 43.3 mJ/m² to 58.5 mJ/m² or by 35% with 60 wt% methanesulfonic acid solution treatment for 36 h. However, the increase with 60 wt% nitric acid solution was only by 14% (to 49.5 mJ/m²) for the same treatment time.     

超级纤维PBO的性能应用及研究进展

在系统介绍21世纪超级纤维及工业材料PBO（聚对苯撑苯并二恶唑）的优异性能与应用领域的基础上，重点叙述了经新单体4，6－二氨基间苯二酚盐酸盐与对苯二甲酸及其衍生物进行缩合共聚制备PBO基体，进而加工成纤维等技术研究的起源和发展，以及当今美国Dow化学,日本Toyobo公司和Nissan化学公司等专利技术的进展，同时针对存在的问题预测了PBO的发展趋势，建议性地提出了国内急需发展PBO研究的目标，内容及今后的方向，即提高新单体的纯度和稳定性，降低成本是PBO技术研究中首要解决的实际问题，而不同的聚合方式，缩聚新技术及单体合成的新方法则是今后十年内PBO材料进一步研究的新内容。     

热处理温度对PBO纤维性能的影响

PBO纤维因其具有高强度、高模量、高耐热性以及高化学稳定性等性能而被公认为目前综合性能最好的有机纤维。对自制的初生PBO纤维分别在500℃、550℃、600℃、650℃和700℃进行高温热处理,并对处理后纤维的力学性能、耐热性能、表面形貌以及界面性能进行测试。结果表明,500℃下热处理后PBO纤维拉伸强度最大为4.72GPa,随着热处理温度升高,纤维的力学性能下降;600℃下热处理后PBO纤维的初始分解温度最高为641.3℃;随着热处理温度的提高,PBO纤维的表面粗糙度在增加,同时其界面剪切强度(IFSS)也随着温度的升高而增大。     

国产PBO纤维研究现状及发展趋势

综述了国产PBO纤维制备过程中在单体合成、聚合物及纺丝的方面的研究现状,表明PBO的单体合成工艺较为成熟,产品纯度高,满足聚合需求;纤维制备具有较好的技术基础,能小批量提供产品,纤维的力学性能与东洋纺Zylon纤维相当。PBO纤维作为一种高强、高模、耐高温材料在航天航空、国防军工、耐高温及增强材料领域得到了广泛的应用,具有良好的市场前景。     

用正交实验设计法优化由间苯二酚合成PBO单体盐酸盐的工艺条件

以间苯二酚为原料,经过发烟硫酸磺化、浓硝酸硝化以及水解反应可制备4,6-二硝基间苯二酚(DNBDO),该方法具有原料易得、产品纯度高、产率高等诸多优点。本文用正交实验设计对该合成方法进行了研究,得出了最优化的反应条件。     

PBO纤维片材加固混凝土弯曲性能研究

采用单向PBO纤维片材对混凝土试件进行了层状增强试验研究.采用三点弯曲试验测试了纤维体积含量对试件弯曲性能的影响,结合数码扫描技术分析了试件断裂形式.结果表明,PBO纤维片材的加入显著提高了混凝土的弯曲强度,并且混凝土弯曲强度随着纤维体积含量的增加而增加,纤维增强混凝土结构中纤维体积含量达到1.35%时的弯曲强度为素混凝土的3.6倍,混凝土的破坏形式由素混凝土的脆性断裂改变为韧性断裂.     

Effect of MWCNTs irradiation grafting treatment on the surface properties of PBO fiber

The aim of this article is improved the surface properties of Poly[p‐phenylenebenzobisoxazole] (PBO) fiber with epichlorohydrin hybridized carboxylic multi walled carbon nanotubes (MWCNTs‐Ecp) grafting by using γ‐ray irradiation technology. The surface chemical properties, the surface morphology, the amount of the grafted MWCNTs on PBO fiber and the surface free energy of PBO fibers have been analyzed. The results show that MWCNTs‐Ecp have been grafted on the surface of PBO fiber by γ‐ray irradiation treatment. The surface chemical inertness and the surface smoothness of PBO fiber are significantly improved by grafting MWCNTs‐Ecp chains, the amount of the grafted MWCNTs on PBO fiber is about 11.9%, and the surface free energy of PBO fiber has an increase of 42.6% by generating some active groups such as ? COOH, ? OH, and ? C? Cl on the surface of PBO fiber. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

EP/PBO复合材料的制备工艺研究

采用自制的专用处理剂处理聚对苯撑苯并双恶唑(PBO)纤维,研究了PBO纤维增强环氧树脂(EP)(EP/PBO)复合材料的配方体系与制备工艺参数.研究表明,采用EP与4,4-二胺基二苯甲烷(DDS)混合制备的复合材料的剪切强度最高.控制预浸胶带的含胶量为35%～37%,在适宜的缠绕工艺参数与固化条件下,制备的EP/PBO复合材料的NOL环剪切强度达26.28～29.32 MPa.     

有机化蛭石填充改性PBO纤维织物衬垫材料的摩擦学性能

采用栓-盘式摩擦磨损试验机研究有机化蛭石改性聚苯撑苯并双噁唑(PBO)纤维织物衬垫材料的摩擦磨损性能,并采用红外光谱仪、X射线衍射仪和扫描电子显微镜对有机化蛭石的结构以及衬垫材料磨损表面和偶件表面进行表征和分析。结果表明,蛭石经过有机化,不仅增强了与树脂的界面结合强度,同时在摩擦过程中易于剥离成片状结构,可以有效地提高PBO纤维织物衬垫材料的抗磨性能。