多聚磷酸/乙酸体系对PBO纤维表面改性的研究

采用多聚磷酸/乙酸体系并结合偶联剂处理方法对PBO纤维表面进行化学改性,采用扫描电镜和液滴形状法对处理前后纤维表面形态结构和纤维表面亲水性进行了表征,通过单丝拔出试验测定了改性前后PBO纤维与环氧树脂基体的界面剪切强度。利用X光电子能谱和热重分析等方法对纤维表面元素组成和热稳定性进行了分析。研究发现,多聚磷酸/乙酸体系偶联剂的方法改性后PBO纤维表面亲水性明显增强,与水的接触角从大于90°下降到42.8,°PBO纤维/环氧树脂的界面剪切强度较未处理样品提高了45%。     

超高分子量聚乙烯纤维表面改性的研究进展

超高分子量聚乙烯(UHMWPE)纤维具有诸多优异性能,因此被广泛应用于纤维增强复合材料(FRP)。但是由于UHMWPE纤维表面光滑且无极性基团,与树脂基体粘接性差,可通过纤维表面改性有效提高FRP的界面强度,进而提升材料性能。本文总结了近几年基于化学处理、等离子体处理、电晕放电和辐射引发表面接枝等方法对UHMWPE纤维表面改性的研究进展,并对改性方法的发展进行了展望。     

高性能纤维表面改性及其双马树脂基复合材料界面

采用电感耦合射频等离子体(ICP)和介质阻挡放电(DBD)低温等离子体对高性能连续纤维表面进行改性,分别采用X光电子能谱(XPS)、原子力显微镜(AFM)和动态接触角测定仪(DCA)等分析测试手段系统地研究了等离子体处理时间、放电功率、放电气压等对连续碳纤维、聚苯并二噁唑(PBO)纤维改性处理前后,纤维表面状态、表面组成、表面形貌、浸润性能的变化规律以及经等离子体处理前后纤维增强双马树脂基复合材料界面结构与性能的影响关系及变化规律、复合材料界面粘结和破坏机理.研究结果表明,经过等离子体处理后,纤维表面接枝上了大量的含羧基、羟基等极性官能团,表面粗糙度增加,表面自由能增加,纤维浸润性能得到明显改善,导致纤维与双马树脂基体界面层间剪切强度(ILSS)明显提高,复合材料的破坏模式由未处理的界面脱粘破坏转变为等离子体处理后的树脂基体破坏.最后,对纤维表面时效性及其对纤维增强双马树脂基复合材料界面性能的影响关系也进行了论述.     

甲基磺酸对PBO纤维的表面改性

采用甲基磺酸(MSA)溶液对PBO纤维表面进行化学改性,用单丝拔出试验测定了改性前后PBO纤维与环氧树脂基体的界面剪切强度,并通过扫描电镜(SEM)、X-射线光电子能谱(XPS)、接触角分别对处理前后纤维的表面形貌、表面组成以及表面自由能进行了表征.研究结果表明:在甲基磺酸质量分数为60%的溶液中,60℃下处理6 h的PBO纤维与环氧树脂基体的界面剪切强度比未处理的提高了81%,并且纤维表面O元素的质量分数增加了13.3%,表面自由能增加了17.3%.当溶液中甲基磺酸的质量分数、处理时间和处理温度进一步提高时,PBO纤维的皮层将遭受破坏,导致界面剪切强度下降.     

PBO纤维界面粘结性能的研究进展

介绍了PBO(聚对苯撑苯并双噁唑)纤维的结构与性能,并针对该纤维作为复合材料增强体与树脂界面粘结性差的特点,评述了PBO纤维表面改性技术中的化学法、共聚改性、偶联剂处理、等离子处理、电晕处理和辐射处理法的研究进展,并比较了各种方法的改性效果及各自优缺点。     

静电纺丝复合反渗透膜的改性制备与脱盐性能

利用静电纺丝技术在无纺布上制备PET纳米纤维膜, 并用交联壳聚糖对其进行改性得到壳聚糖改性纳米纤维复合膜. 以间苯二胺(MPD)和均苯三甲酰氯(TMC)为单体, 采用界面聚合法在壳聚糖改性纳米纤维复合膜的表面制备聚酰胺分离层, 得到新型静电纺丝纳米纤维基复合反渗透膜. 新型复合反渗透膜具有典型的聚酰胺复合反渗透膜的表面脊-谷结构. 从膜的表面形貌、 亲水性、 分离性能等3个方面对水相MPD溶液中阴离子表面活性剂十二烷基苯磺酸钠(SDBS)的含量对膜结构和性能的影响进行了系统研究. 结果表明, SDBS的含量对膜形态结构的均匀性和亲水性有一定影响, 且随着SDBS含量的增加, 膜的脱盐率先增大后减小, 而通量小幅度上升后, 先减小后增大, 呈现规律性变化.     

低温等离子体对超高分子聚乙烯纤维表面改性研究

介绍了低温等离子放电技术的概念、原理、实施方法及其在超高分子量聚乙烯（UHMWPE）纤维表面改性方面的应用。综述了国内外低温等离子体对UHMWPE纤维表面改性的最新研究成果,阐述了气体等离子体种类、处理功率和处理时间等因素对UHMWPE纤维表面改性效果的影响机理,以及低温等离子设备对UHMWPE纤维表面改性连续化的初步...     

表面改性对VGCF分散性质的影响

针对气相生长碳纤维极易团聚及与树脂基体界面结合能力较差的难题,采用双氧水-浓硝酸二步法对VGCF进行表面改性处理。利用X射线衍射仪、热重分析仪、傅立叶红外光谱仪、紫外可见分光光度计等测试分析了改性前后VGCF的表面结构和在溶剂中的分散性,并以形状记忆聚氨酯为基体,采用溶液混合法制备了气相生长碳纤维/形状记忆聚氨酯的复合材料,测试了复合材料的力学性能。经过改性后,VGCF的石墨晶型结构几乎没有改变,VGCF表面的含氧官能团浓度得到较大提高,且其在有机溶剂中的分散性及分散稳定性也得到很大提高;在气相生长碳纤维/形状记忆聚氨酯的复合材料截面中,扫描电镜观察表明表面改性使得VGCF在基体中的分散性及与基体的界面结合能力都得到一定程度的提高;经二步法改性处理后的气相生长碳纤维比未处理气相生长碳纤维对复合材料的力学性能的增强效果更为明显。     

液态氧化法处理超高分子量聚乙烯纤维

用液态氧化法对超高分子量聚乙烯纤维进行了表面处理,研究了处理介质、处理时间对超高分子量聚乙烯／环氧复合材料层间剪切强度的影响,用扫描电子显微镜、ＸＰＳ表面元素分析、毛细浸润法测接触角等方法探讨了纤维表面性能处理前后的变化,以及纤维与树脂的界面结合情况。     

连续纤维增强含二氮杂萘酮联苯结构聚芳醚砜酮树脂基复合材料的界面

利用射频感性耦合冷等离子体(ICP)处理技术改性连续纤维表面,分别采用X射线光电子能谱(XPS)、原子力显微镜(AFM)及动态接触角分析(DCA)系统研究了等离子体处理时间、放电气压、放电功率等工艺参数对连续碳纤维、芳纶纤维和对亚苯基苯并二噁唑(PBO)纤维的表面化学成分、表面形貌、表面粗糙度及表面自由能的影响.研究结...     

Surface modification of PBO fibers with 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane in supercritical carbon dioxide for enhancing interfacial strength

PBO fiber is one of the most promising reinforcements in resin matrix composite because of its excellent mechanical properties. However, the inert and smooth surfaces make it the poor interface adhesion with resin matrix, which seriously limits the application in composites. In this article, we report a method to modify the surface of PBO fibers with 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane（BisAPAF）in supercritical CO₂ to enhance interfacial properties. Chemical structures, surface elemental composition and functional groups, and surface morphology were characterized by FT-IR spectrometer, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), respectively. The mechanical properties of the samples were tested by a tensile tester. Static contact angle and microdebonding tests were used to characterize the wetting ability and interfacial shear strength (IFSS) of the fiber and epoxy resin. The results showed that the BisAPAF could be solved in scCO₂ and introduced more groups, –NH₂, –OH, and –CF₃ on the fiber surface, resulting in the mechanical properties and the wettability of PBO fiber slightly improved. Moreover, the fiber surface roughness was also increased obviously. The IFSS between the modified PBO fiber and epoxy resin increased from 8.18 MPa to 31.4 MPa when the treating pressure was 14 MPa. In general, the method to modify PBO fibers surface using BisAPAF in scCO₂ can effectively improve their interfacial properties.     

Improvement of surface wettability and interfacial adhesion ability of poly(p-phenylene benzobisoxazole) (PBO) fiber by incorporation of 2,5-dihydroxyterephthalic acid (DHTA)

By introducing 2,5-dihydroxyterephthalic acid (DHTA) into poly(p-phenylene benzoxazole) (PBO) macromolecular chains, dihydroxy poly(p-phenylene benzobisoxazole) (DHPBO) was synthesized and then DHPBO fibers were prepared by dry-jet wet-spinning method. Effects of hydroxyl polar groups on surface wettability and interfacial adhesion ability of PBO fiber were investigated. With the incorporation of double hydroxyl polar groups, contact angle on PBO fiber for water can decrease from 71.4° to 50.70°, and contact angle for ethanol can decrease from 37.2° to 27.40°. The wetting time on DHPBO fibers for water can be as short as 650 ms, which is half of that of PBO fibers. The interfacial shearing strength (IFSS) between DHPBO (10% mol content DHTA) fibers and epoxy resin is 18.87 MPa, 92.55% higher than that of PBO fibers. SEM images indicate that the PBO/epoxy composite failure mode may change from fiber/matrix adhesive failure to partially cohesive failure.     

Improvement of interfacial adhesion and nondestructive damage evaluation for plasma-treated PBO and Kevlar fibers/epoxy composites using micromechanical techniques and surface wettability

Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole (PBO, Zylon) and poly(p-phenylene terephthalamide) (PPTA, Kevlar) fibers/epoxy composites were investigated using a micromechanical technique and nondestructive acoustic emission (AE). The interfacial shear strength (IFSS) and work of adhesion, Wa, of PBO or Kevlar fiber/epoxy composites increased with oxygen-plasma treatment, due to induced hydrogen and covalent bondings at their interface. Plasma-treated Kevlar fiber showed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum values. The work of adhesion and the polar term were proportional to the IFSS directly for both PBO and Kevlar fibers. The microfibril fracture pattern of two plasma-treated fibers appeared obviously. Unlike in slow cooling, in rapid cooling, case kink band and kicking in PBO fiber appeared, whereas buckling in the Kevlar fiber was observed mainly due to compressive and residual stresses. Based on the propagation of microfibril failure toward the core region, the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly compared to the untreated case. The results of nondestructive AE were consistent with microfailure modes.     

Aging behavior of PBO fibers and PBO‐fiber‐reinforced PPESK composite after oxygen plasma treatment

Aging behavior of poly(p‐phenylene benzobisoxazole) (PBO) fibers and PBO‐fiber‐reinforced poly(phthalazinone ether sulfone ketone) (PPESK) composites after oxygen plasma treatment was investigated. Surface chemical composition, surface roughness and surface morphologies of oxygen‐plasma‐treated PBO fibers before and after aging in air for 1, 3, 5 and 10 days were analyzed by XPS and atomic force microscopy (AFM). The effects of aging on the material were examined by interlaminar shear strength (ILSS) and water absorption measurements. The results indicate that the major aging behavior of the fibers and the composite appeared in the first few days after oxygen plasma treatment, whereas minor aging effects were observed with prolonged aging. Copyright © 2008 John Wiley & Sons, Ltd.     

Improvement of PBO fiber surface and PBO/PPESK composite interface properties with air DBD plasma treatment

The interface of fibrous composites is a key factor to the whole properties of the composites. In this study, the effects of air dielectric barrier discharge (DBD) plasma discharge power density on surface properties of poly(p‐phenylene benzobisoxazole) (PBO) fiber and the interfacial adhesion of PBO fiber reinforced poly(phthalazinone ether sulfone ketone) (PPESK) composite were investigated by several characterization methods, including XPS, SEM, signal fiber tensile strength, interlaminar shear strength, and water absorption. After the air DBD plasma treatment at a power density of 41.4 W/cm³, XPS analysis showed that some polar functional groups were introduced on the PBO fiber surface, especially the emergence of a new oxygen‐containing group (?O–C = O group). SEM observations revealed that the air DBD plasma treatment had a great influence on surface morphologies of the PBO fiber, while the signal fiber tensile strength results showed only a small decline of 5.9% for the plasma‐treated fiber. Meanwhile, interlaminar shear strength value of PBO/PPESK composite was increased to 44.71 MPa by 34.5% and water absorption of the composite decreased from 0.46% for the untreated specimen to 0.27%. The results showed that the air DBD plasma treatment can effectively improve the properties of the PBO fiber surface and the PBO/PPESK composite interface. Results obtained from the above analyses also showed that both the fiber surface and the composite interface performance would be reduced when an undue plasma discharge power density was applied. Copyright © 2011 John Wiley & Sons, Ltd.     

In situ polymerization and characterization of graphene oxide‐co‐poly(phenylene benzobisoxazole) copolymer fibers derived from composite inner salts

A facile and efficient strategy for preparing well dispersed graphene oxide (GO)‐co‐Poly(phenylene benzobisoxazole) (PBO) copolymer fibers was carried out by direct in situ polycondensation of composite inner salts. The composite inner salts were achieved to improve the dispersivity, solubility, reactivity, and interfacial adhesion of GO in PBO polymer matrix. The structure and morphology of GO‐co‐PBO copolymer fibers have been characterized. It was demonstrated that GO were covalently incorporated with PBO molecular chains and dispersed considerably well in PBO fiber even the GO reach to 3 wt %. Meanwhile, the tensile modulus, tensile strength and thermal stability of GO‐co‐PBO copolymer fibers increased considerably with GO. The mechanism and theoretical calculation of GO enhanced PBO fiber were also discussed. The main reasons for the improvement on performance of PBO fiber should be attributed to good dispersion GO in PBO matrix and covalent bonding networks at the interface between GO and PBO molecular chains. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

The effect of coupling agents on the interfacial properties of wood‐fiber–reinforced polyimide composites

Wood‐fiber–reinforced polyimide (PI) has been widely used in many engineering fields because of its high specific strength and stiffness. However, PI does not adhere well with wood fibers because it has a low free surface energy. In addition, high viscosity in the melted phase causes poor impregnation. In this study, surface treatment methods, ie, coupling agents with plasma treatment on wood fibers, were applied to increase the interfacial strength between the wood fibers and the PI matrix. The modified wood fiber surfaces were analyzed by X‐ray photoelectron spectroscopy and scanning electron microscopy. To analyze the effectiveness of the surface treatment method, the interlaminar shear strength (ILSS) was measured using the 3‐point bending test. From the test results, the ILSS of the specimens treated with the silane coupling agent after the plasma treatment increased by 48.7% compared with those of the untreated specimens.     

Surface modification of high-performance polymeric fibers by an oxygen plasma. A comparative study of poly(p-phenylene terephthalamide) and poly(p-phenylene benzobisoxazole)

Poly(p-phenylene terephthalamide) (PPTA) and poly(p-phenylene benzobisoxazole) (PBO) fibers were exposed to an oxygen plasma under equivalent conditions. The resulting changes in the surface properties of PPTA and PBO were comparatively investigated using inverse gas chromatography (IGC) and atomic force microscopy (AFM). Both non-polar (n-alkanes) and polar probes of different acid-base characteristics were used in IGC adsorption experiments. Following plasma exposure, size-exclusion phenomena, probably associated to the formation of pores (nanoroughness), were detected with the largest n-alkanes (C(9) and C(10)). From the adsorption of polar probes, an increase in the number or strength of the acidic and basic sites present at the fiber surfaces following plasma treatment was detected. The effects of the oxygen plasma treatments were similar for PPTA and PBO. In both cases, oxygen plasma introduces polar groups onto the surfaces, involving an increase in the degree of surface nanoroughness. AFM measurements evidenced substantial changes in the surface morphology at the nanometer scale, especially after plasma exposure for a long time. For the PBO fibers, the outermost layer - contaminant substances - was removed thanks to the plasma treatment, which indicates that this agent had a surface cleaning effect.