Rigid‐rod polymeric fibers

This paper traces the historical development of high temperature resistant rigid‐rod polymers. Synthesis, fiber processing, structure, properties, and applications of poly(p‐phenylene benzobisoxazole) (PBO) fibers have been discussed. After nearly 20 years of development in the United States and Japan, PBO fiber was commercialized with the trade name Zylon® in 1998. Properties of this fiber have been compared with the properties of poly(ethylene terephthalate) (PET), thermotropic polyester (Vectran®), extended chain polyethylene (Spectra®), p‐aramid (Kevlar®), m‐aramid (Nomex®), aramid copolymer (Technora®), polyimide (PBI), steel, and the experimental high compressive strength rigid‐rod polymeric fiber (PIPD, M5). PBO is currently the highest tensile modulus, highest tensile strength, and most thermally stable commercial polymeric fiber. However, PBO has low axial compressive strength and poor resistance to ultraviolet and visible radiation. The fiber also looses tensile strength in hot and humid environment. In the coming decades, further improvements in tensile strength (10–20 GPa range), compressive strength, and radiation resistance are expected in polymeric fibers. Incorporation of carbon nanotubes is expected to result in the development of next generation high performance polymeric fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 100: 791–802, 2006     

Poly(p‐phenylene benzoxazole) fiber chemically modified by the incorporation of sulfonate groups

Two kinds of modified poly(p‐phenylene benzoxazole) (PBO), the copolymer of TPA (SPBO) and p‐SPBO, containing ionic groups in the macromolecular chains were obtained by copolymerization from 1,3‐diamino‐4,6‐dihydroxybenzene dihydrochloride (DAR) and terephthalic acid (TPA), with the addition of selected amounts (1.5–5.0% molar ratio over DAR) of 5‐sulfoisophthalic acid monosodium salt or sulfoterephthalic acid monopotassium salt in place of the TPA, respectively, in poly(phosphoric acid) (PPA). The resultant PBO/PPA, SPBO/PPA, and p‐SPBO/PPA lyotropic liquid‐crystalline solutions were spun into fibers by a dry‐jet wet‐spinning technique. Chemically modified PBO fibers with sulfonate salt pendants in the polymer chains were obtained for the first time. The surface wetting behavior and interfacial shear strength between the fiber and epoxy resin were investigated. The interference of sulfonate salt pendants on the crystalline morphology was measured. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Fabrication of uvioresistant poly(p-phenylene benzobisoxazole) fibers based on hydrogen bond

The poly(p-phenylene benzobisoxazole) (PBO) fiber with excellent performance is vulnerable to the irradiation of UV light, which significantly limits their application in advanced composites. Therefore, finding feasible and efficient ways to improve the uvioresistant properties of PBO fiber is of significance. In this work, a facile one-pot method is developed for continuously preparing the PBO/poly(2,5-dihydroxy-1, 4-phenylpyridimidazole) (PIPD) copolymer fiber to greatly enhance the anti-UV properties of PBO fibers. The experimental results demonstrate that the fabricated PBO/PIPD copolymer fiber (molar ratio of 7:1) with greatly improved surface wetting properties (the maximum increase can reach about 179%) possesses satisfactory and desired uvioresistant performance, which is 30.8% higher than that of pure PBO fibers after 480 h UV aging irradiation. The fabricated PBO/PIPD copolymer fiber with improved UV stability has the potential to be applied to many important application areas even in a severe and harsh environment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48432.     

Influence of oxygen plasma treatment on interfacial properties of poly(p‐phenylene benzobisoxazole) fiber‐reinforced poly(phthalazinone ether sulfone ketone) composite

The influence of oxygen plasma treatment on both surface properties of poly(p‐phenylene benzobisoxazole) (PBO) fibers and interfacial properties of PBO fiber reinforced poly(phthalazinone ether sulfone ketone) (PPESK) composite were investigated. Surface chemical composition, surface roughness, and surface morphologies of PBO fibers were analyzed by X‐ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM), and scanning electron microscopy (SEM), respectively. Surface free energy of the fibers was characterized by dynamic contact angle analysis (DCAA). The interlaminar shear strength (ILSS) and water absorption of PBO fiber‐reinforced PPESK composite were measured. Fracture mechanisms of the composite were examined by SEM. The results indicated that oxygen plasma treatment significantly improved the interfacial adhesion of PBO fiber‐reinforced PPESK composite by introducing some polar or oxygen‐containing groups to PBO fiber surfaces and by fiber surface roughening. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

聚苯并噁唑(PBO)的合成及其应用研究

聚苯并噁唑(PB0)因其具有的强度大、耐高温、耐氧化、耐潮湿以及优良的热稳定性等特点，自20世纪80年代以来一直是人们关注的热点之一。综述了PB0的合成方法，如多磷酸法、中间相聚合法、三甲基硅烷基化法、对羟基苯甲酸酯法，并介绍了PB0纤维的性质，对其应用前景作了展望。     

Shear flow behaviors of poly(p‐phenylene benzobisoxazole) spinning dope

In this study, the shear flow properties of Poly(p‐phenylene benzobisoxazole) (PBO)/poly(phosphoric acid) (PPA) spinning dope were studied by means of capillary rheometer. The effect of shear stress, temperature, PBO concentration, and PBO molecular weight on the apparent viscosity of PBO/PPA dope was discussed. The results showed that the apparent viscosity of the dope decreased with the increase of the shear stress and the temperature. The flow behavior index increased with the increase of temperature, which indicated that the non‐Newtonian behavior of the dope became weaker at high temperature. Moreover, it was also found that at high shear stress, the apparent viscosity of the dope was insensitive to the temperature, PBO molecular weight, and PBO concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Fiber hybrid polyimide‐based composites reinforced with carbon fiber and poly‐p‐phenylene benzobisthiazole fiber: Tribological behaviors under sea water lubrication

Fiber hybrid polyimide‐based (PI‐based) composites reinforced with carbon fiber (CF) and poly‐p‐phenylene benzobisthiazole (PBO) fiber of different volume fractions were fabricated by means of hot press molding technique, and their mechanical properties and tribological behaviors under sea water lubrication were systematically investigated in relation to the synergism of CF and PBO fiber. Results showed that the incorporation of CF or PBO fiber improved the tensile strength, hardness, and wear resistance of PI. More importantly, because of the synergistic enhancement effect between CF and PBO fiber on PI matrix, the combination of 10%CF and 5%PBO fiber reinforced PI‐based composite had the best mechanical and tribological properties, showing promising application in ocean environment. POLYM. COMPOS., 37:1650–1658, 2016. © 2014 Society of Plastics Engineers     

PBO纤维及其改性的研究进展

简述了聚对苯撑苯并双噁唑(PBO)纤维的结构与性能;详述了PBO纤维的改性研究进展。PBO纤维的改性主要是改善其抗压性能和表面粘结性能。提高微纤间相互作用或交联等方法可提高PBO纤维的压缩强度;通过酸处理、偶联剂处理、等离子体处理及电晕处理等方法可提高PBO纤维的表面粘结性能。指出表面改性仍将是PBO纤维改性研究的重点。     

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。     

Heat resistance properties of poly(p-phenylene-2,6-benzobisoxazole) fiber

The high temperature properties of Poly(p-phenylene-2,6-benzobisoxazole) (PBO) fiber are examined and compared with those of the p-Aramid fiber. In particular, the temperature dependence of tensile strength of the PBO fiber is reported for the first time. The PBO fiber has 100°C higher decomposition temperature than the p-Aramid fiber, and the amount of toxic gases in combustion is much smaller than the p-Aramid fiber. Although the relative strength decreased proportionally in the range of room temperature to 500°C, the PBO fiber has 40% of the strength at room temperature even at a temperature of 500°C. After thermal treatment at 500°C for 60 s, the PBO fiber retained 90% of its original strength. The PBO fiber is expected to substitute for asbestos, which is still used as a heat resistant cushion material. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1031–1036, 1997     

国产PBO纤维的性能及形貌研究

采用扫描电子显微镜、元素分析仪、热分析仪以及复合材料单向环(NOL)法等对国产聚对苯撑苯并双噁唑(PBO)纤维和东洋纺Zylon纤维的形貌、元素组成、热性能和力学性能进行了比较分析。结果表明:Zylon纤维单丝直径约为12μm,国产PBO纤维直径稍大,约为20μm;Zylon纤维表面较为光滑和致密,国产PBO纤维表面存在微小的浅沟槽;国产PBO纤维的断裂强度最高达5.36 GPa,模量最大为239 GPa,分别比Zylon纤维低7.6%和14.6%,但其NOL环的层间剪切强度最高达26 MPa,比Zylon纤维制备的复合材料高14%;国产PBO纤维与Zylon纤维的组成基本一致,但其耐热性能优异,在氮气中的分解温度大于676℃,在空气中的分解温度大于634℃,分别比Zylon纤维高6℃和23℃。     

PBO纤维的性能及应用

介绍了聚对苯撑苯并双噁唑(PBO)纤维的结构特点、性能及应用。PBO纤维分子沿轴向高度取向,其强度和初始模量高,具有耐热、阻燃、耐冲击、耐弯曲疲劳和耐化学稳定性等优良性能。PBO纤维在耐热材料、增强材料、防弹抗冲击材料以及航空领域与军事领域广泛应用。     

Synthesis and characterization of a rigid-rod dihydroxy poly(<Emphasis Type="Italic">p</Emphasis>-phenylene benzobisoxazole) fiber with excellent surface and axial compression properties

A series of dihydroxy poly(p-phenylene benzobisoxazole) (DHPBO) were prepared by introducing binary hydroxyl polar groups into poly(p-phenylene benzoxazole) PBO macromolecular chains and the effects of hydroxyl polar groups on surface wettability, interfacial adhesion and axial compression property of PBO fiber were investigated. Contact angle measurement showed that the wetting process both for water and for ethanol on DHPBO fibers were obviously shorter than that on PBO fibers, implying DHPBO fibers have a higher surface free energy. Meanwhile, single fiber pull-out test showed that DHPBO fibers had higher interfacial shear strength than that of PBO fibers. Scanning electron microscope proved that there was more resin remained on the surface of DHPBO fibers than on PBO fibers after pull-out test. Furthermore, axial compression bending test showed that the introduction of binary hydroxyl groups into macromolecular chains apparently improved the equivalent bending modulus of DHPBO fibers.     

多聚磷酸改性PBO纤维的研究

采用多聚磷酸及其乙醇溶液(体积比1:1)对聚对苯二撑苯并二噁唑(PBO)纤维进行表面处理。通过单丝拔出剪切强度的测试来表征纤维／树脂的界面粘结性能,并通过液滴形态法来表征纤维的表面润湿性能,利用扫描电镜和X射线衍射分析探讨了表面形态及结晶结构在改性前后的变化。结果表明:PBO纤维经两种溶液分别处理1 min,5 min后,纤维／树脂的界面粘结强度分别提高24％,55％,但单丝强度均下降;纤维与水的接触角由大于90°均降低至45°左右;结晶度从原丝的56.4％分别降低至52.9％,52.3％。     

PBO纤维稳定性的研究进展

介绍了聚对苯撑苯并双噁唑(PBO)纤维的热分解行为、热分解机理、水解稳定性、光稳定性及化学稳定性等方面的研究进展。PBO纤维的热稳定性和化学稳定性优良,其水解稳定性和光稳定性较差。通过热处理可提高PBO纤维的强度和模量。指出应进一步研究PBO纤维的稳定性,提高其性能,扩大应用领域。     

Improved longitudinal compression performance of a unidirectional fiber‐reinforced composite with a filament covering

A filament covering is proposed to improve the longitudinal compressive properties of unidirectional fiber reinforced plastic. Based on compressive buckling theory, fiber buckling can be prevented by shortening the buckling critical wavelength by covering the filament. In this paper, a UHMWPE fiber bundle and a PBO filament were selected as the reinforcing fiber and the covering filament, respectively, to verify this statement. The effect of a covering PBO filament on a UHMWPE fiber reinforced epoxy resin on compressive performance was investigated by a compressive test and morphology observations. Results show that the filament covering has positive effect on the compressive strength of the FRP, and the tension‐exerted filament covering increased the compressive strength and increased the longitudinal compressive modulus of the UFRP. POLYM. COMPOS., 37:3127–3133, 2016. © 2015 Society of Plastics Engineers     

X‐ray scattering study on the damage in fibers used in soft body armor after folding

The goals of the research effort described in this article are to develop a framework to evaluate improvements in next‐generation fibers used in soft body armor and to anticipate long‐term performance and potential fiber deterioration. This effort to date has included the effect of folding on the fibers and exploring the interaction between the specific fiber strain energy and their sound velocity. Previous work in this lab noted a severe drop‐off of tensile strength and strain‐to‐failure in poly(p‐phenylene benzobisoxazole) (PBO) fibers when subjected to repeated folding. Subsequent work on poly(p‐phenylene terephthalamide) (PPTA) fibers showed at most a slight drop‐off in these mechanical properties. Results from wide angle X‐ray diffraction indicated that both PPTA and PBO fibers showed no significant changes in the d‐spacing and the apparent crystal size. However, with small angle X‐ray scattering, it was found that the void and fibril sizes within PBO fibers may decrease after folding. Environmental scanning electron microscopy showed no damage to the fiber surfaces upon folding, and confocal microscopy revealed extensive internal damage to the PBO fibers that tracks well with the SAXS and mechanical testing results. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Rigid‐Rod Polymers: Synthesis,Processing, Simulation,Structure, and Properties

Synthesis, structure, and properties of rigid‐rod polymers with special emphasis on poly(p‐phenylene benzobisoxazole) (PBO) and poly(p‐phenylene benzobisthiazole) (PBZT) have been reviewed. Recent studies on chemical modifications and molecular simulations have also been given. After nearly 20 years of research and development, PBO fiber was commercialized in the late 1990s. However, due to processing difficulties, the concept of the so called molecular composites has not been successful. Development of the high compressive strength M5 and dihydroxy‐PBI fibers clearly suggest that there is potential for further developing properties of this class of materials. Opto‐electronic properties have also been reviewed.

Synthesis of PBZT.     

Promoting the adhesion of high‐performance polymer fibers using functional plasma polymer coatings

Plasma‐copolymerized functional coatings of acrylic acid and 1,7‐octadiene were deposited onto high strength, high modulus, poly‐p‐phenylene benzobisoxazole (PBO) fibers. X‐ray photoelectron spectroscopy (XPS) with trifluoroethanol derivatization confirmed that the PBO fibers were covered completely with the plasma copolymer and that the coating contained a quantitative concentration of carboxylic acid groups. Microdebond single filament adhesion and interlaminar shear strength (ILSS) tests were used to evaluate the interfacial strength of epoxy resin composites containing these functionalized PBO fibers. Both the interfacial shear strength (IFSS) obtained from single filament tests, and the ILSS of high volume fraction composites were a function of the surface functionality of the fibers so that there was a good correlation between ILSS and IFSS data. The tensile strengths of single fibers with or without coating were comparable, demonstrating that the fiber surface was not damaged in the plasma‐coating procedure. Indeed, the statistical analysis showed that Weibull modulus was increased. Therefore, plasma‐polymerized coatings can be used to control the interfacial bond between PBO fibers and matrix resins and act as a protective size for preserving the mechanical properties of the fibers. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Compressive behaviour of rigid rod polymer fibres and their adhesion to composite matrixes

Abstract

The deformation behaviour of the new high performance polymer fibres, poly(p-phenylene benzobisoxazole) (PBO) and polypyridobisimidazole (PIPD) and their adhesion to an epoxy composite matrix have been investigated. Both fibres give well defined Raman spectra, and the deformation micromechanics of PBO and PIPD single fibres and composites were studied from stress induced Raman band shifts. Single fibre stress-strain curves were determined in both tension and compression, thus providing an estimate of the compressive strength of these fibres. It was found that the PIPD fibre has a higher compressive strength (~1 GPa) than PBO (~0·3 GPa) and other high performance polymer fibres, because hydrogen bond formation is possible between PIPD molecules. It has been shown that when PBO and PIPD fibres are incorporated into an epoxy resin matrix, the resulting composites show very different interfacial failure mechanisms. The fibre strain distribution in the PBO-epoxy composites follows that predicted by the full bonding, shear lag model at low matrix strains, but deviations occur at higher matrix strains due to debonding at the fibre/matrix interface. For PIPD-epoxy composites, however, no debonding was observed before fibre fragmentation, indicating better adhesion than for PBO as a result of reactive groups on the PIPD fibre surface.