AB型羟基改性PBO单体及其合成新技术

提出单羟基改性PBO及其AB型单体的分子结构,研究了以4-氨基-6-硝基间苯二酚盐酸盐(ANR·HCl)和羟基对苯二甲酸(HTA)为原料直接缩环合制备2-羟基-4-(5-硝基-6-羟基苯并 唑-2-基)苯甲酸(HNBA)、再还原合成AB型单体:2-羟基-4-(5-氨基-6-羟基苯并 唑-2-基)苯甲酸(HABA)的新方法。结果表明:缩环合制备的HNBA,其纯度96.81%、收率69.25%;进一步还原合成出纯度>98%的单体HABA,以ANR·HCl计的总收率为58.38%;具有原料易得、步骤短、条件缓和、产物稳定性优异以及缩聚基团完全等当比等性质。合成的新单体HABA及其前体HNBA,经FT-IR和MS以及NMR等分析和表征,证实了其分子结构。     

PBO纤维耐热性研究及进展

根据近几年国内外关于PBO纤维耐热性的报道,结合作者对其耐热性的研究,综述了PBO纤维的高温行为,并与几种高性能纤维进行了比较,从PBO纤维的强度降低、模量变化和高温老化分解等几个方面进行了较为详细的分析.     

Study on photoaging of poly(p‐phenylene benzobisoxazole) fiber

As a kind of rig‐rod‐like polymer, poly(p‐phenylene benzobisoxazole) (PBO) has received great interest because of its excellent mechanical properties and good thermal stability. The use of PBO fibers, however, is limited due to its low sunlight stability. In this work, the photoaging of PBO fibers, as well as the effects of oxygen and moisture on their photoaging, is investigated by tensile strength measurements, infrared spectroscopy, molecular mass determination, and scanning electron microscopy. It is first time to find that the photoaging of PBO fibers includes two development stages. The physical aging is the dominate factor at the first stage of photoaging relative to the second stage, in which the chemical aging is the dominate factor. In the first degradation stage, long defects appear and develop parallel to the fiber axis. Little chemical change occurs in this stage. In the second degradation stage, the molecular mass of PBO decreases and chemical degradation occurs. Oxygen accelerates the occurrence of chemical degradation. It is also found PBO fibers are more stable for photoaging when moisture and oxygen are isolated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Environmental effects on poly‐p‐phenylenebenzobisoxazole fibers. II. Attempts at stabilization

Approaches to alleviate the environmental degradation of as‐spun poly‐p‐phenylenebenzobisoxazole (PBO AS) fibers by moisture, acidic conditions, and UV–visible radiation were implemented and tested for efficacy. The general approaches tested include: extraction and neutralization of residual phosphoric acid using supercritical carbon dioxide; the use of UV–visible light blocking coatings of exfoliated graphite, carbon black, and glassy titanium dioxide; and improvement of initial fiber properties by the application of forces tending to compact the fiber microstructure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3819–3829, 2006     

Investigation of the chemical and morphological structure of thermally rearranged polymers

Reacting ortho-functional poly(hydroxyimide)s via a high-temperature (i.e., 350 °C–450 °C) solid-state reaction produces polymers with exceptional gas separation properties for separations such as CO₂/CH₄, CO₂/N₂, and H₂/CH₄. However, these reactions render these so-called thermally rearranged (TR) polymers insoluble in common solvents, which prevent the use of certain experimental characterization techniques such as solution-state nuclear magnetic resonance (NMR) from identifying their chemical structure. In this work, we seek to identify the chemical structure of TR polymers by synthesizing a partially soluble TR polymer from an ortho-functional poly(hydroxyamide). The chemical structure of this TR polymer was characterized using 1-D and 2-D NMR. By use of cross-polarization magic-angle spinning ¹³C NMR, the structure of the polyamide-based TR polymer was compared to that of a polyimide-based TR polymer with a nearly identical proposed structure. The NMR spectra suggest that oxazole functionality is formed for both of these TR polymers. Furthermore, gas permeation results are provided for the precursor polymers and their corresponding TR polymer. The differences in transport properties for these polymers result from differences in the isomeric nature of oxazole-aromatic linkages and morphological differences related to free volume and free volume distribution.     

Surface modification of PBO fibers by argon plasma and argon plasma combined with coupling agents

The methods of argon plasma and argon plasma combined with coupling agents were employed to modify the poly[1,4‐phenylene‐cis‐benzobisoxazole] (PBO) fiber surface. The interfacial shearing strength (IFSS) of PBO fibers/epoxy resin was measured by the single fiber pull‐out test. The surface chemical structure and surface composition of PBO fibers were determined by FTIR and X‐ray photoelectron spectroscopy respectively. The morphology of the fiber surface was investigated by scanning electron microscopy and the specific surface area of the fibers was calculated by B.E.T. equation. Furthermore, the wettability of PBO fibers was confirmed by the droplet profile analysis method. The results showed that the elemental composition ratio of the fiber surface changed after the modification. The IFSS increased by 42 and 78% when the fibers were treated by argon plasma and argon plasma combined with the coupling agents, respectively. Meanwhile, the specific surface areas of the treated fibers were improved. In addition, compared with the modification of argon plasma, the modification of argon plasma combined with the coupling agents inhibited the attenuation phenomena of the IFSS and the wettability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1428–1435, 2006     

PBO纤维生产工艺的研究

以4，6-二氨基间苯二酚盐酸盐（DAR）和对苯二甲酸（TPA）制成复合盐，再以多聚磷酸为溶剂，添加五氧化二磷，制备出PBO聚合物。通过双螺杆挤出机和喷丝板挤出，在水溶液中凝固成型，经过洗涤、干燥等过程，最终卷绕成型。制成的纤维抗拉强度可以达到33cN／dtex，制成的PBO聚合物特性粘度可以达到56dL/g。     

PBO纤维生产工艺的研究

以4,6-二氨基间苯二酚盐酸盐(DAR)和对苯二甲酸(TPA)制成复合盐,再以多聚磷酸为溶剂,添加五氧化二磷,制备出PBO聚合物。通过双螺杆挤出机和喷丝板挤出,在水溶液中凝固成型,经过洗涤、干燥等过程,最终卷绕成型。制成的纤维抗拉强度可以达到33 cN/dtex,制成的PBO聚合物特性粘度可以达到56 dL/g。     

环氧树脂/PBO纤维复合材料性能研究

对环氧树脂(EP)/聚对苯撑苯并二恶唑(PBO)纤维复合材料的性能进行初步研究。结果表明,用浓度70%的甲基磺酸(MSA)溶液对PBO纤维表面进行处理,可改善PBO纤维与EP基体的粘结强度,但同时使PBO纤维的拉伸性能降低;对PBO纤维处理2h后,以胺类固化剂固化的EP/PBO纤维复合材料的层间剪切强度比处理前提高41%,以酸酐固化剂固化的EP/PBO纤维复合材料的层间剪切强度比处理前提高48%;前者的层间剪切强度大于后者。     

PBO纤维表面改性研究进展

综述了目前PBO纤维的表面改性方法,主要包括等离子体处理、表面化学处理、辐射处理、偶联剂处理以及共聚改性的研究进展。分析了各种改性方法的原理并指出各种改性方法的优势及存在的问题。展望了PBO纤维增强复合材料的应用前景,指出今后纤维表面改性仍是PBO纤维增强树脂复合材料的研究重点。