提高PBO纤维/环氧树脂复合材料界面结合的研究

本文采用表面化学蚀刻与溶胀法结合、化学偶联法与氩气低温等离子体表面处理技术结合的方法对聚苯撑苯并二。唑（PBO）纤维进行表面改性。探讨了不同改性方法对纤维表面性能的影响。同时，采用FTIR和SEM等方法对处理前后纤维表面化学结构及形态进行了表征。     

抗紫外老化聚对苯撑苯并二噁唑(PBO)纤维的制备与表征

通过化学添加2,5-二羟基对苯二甲酸(DHTA)共聚,以及添加金红石型纳米TiO2物理共混的方法,制备了聚对苯撑苯并二噁唑(PBO)的抗紫外改性纤维.考察了纤维的力学性能、特性粘度及表面形貌在紫外老化过程中的变化,并结合PBO纤维紫外加速老化后的红外分析,对PBO纤维的光老化机理进行了初步研究.结果表明,本实验所制备的DHPBO纤维以及DHPBO/n-TiO2纤维的抗紫外老化能力明显高于PBO纤维,并且金红石型纳米TiO2对PBO的抗紫外改性效果要优于有机紫外吸收剂(2,2'-(1,2-乙烷二基)双(4,1-亚苯基)双苯并噁唑).     

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%。     

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纤维的合成及其微观结构

聚对苯撑苯并双唑 (PBO)纤维是一种高强度、高模量、高热稳定性、高耐化学腐蚀性的新型纤维。着重介绍了PBO纤维的合成工艺、纺丝工艺 ;并对PBO的微观结构形态和表征方法进行了综合评述。     

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...     

2-（4-甲氧羰基苯基）-5-硝基-6-羟基苯并噁唑的热分解机理及动力学

顺式聚对苯撑苯并二噁唑(cis-poly-paraphenyl enebenzobisoxazole,简称PBO)引起了人们的重视[1-3]。由PBO制得的高性能纤维的商品名为Zylon[2],Zylon不仅具有高的机械强度,而且具有高的热氧化稳定性[2,4-5]。PBO纤维和PBO复合材料在宇航、武器装备等领域中有广阔的应用前景[1-     

高性能PBO纤维的成型、性能改善及其应用研究北大核心CSCD

聚苯撑苯并二噁唑(PBO)纤维具有超高强度和模量、优异的耐热性和阻燃性,是一种在国防军工、航空航天等领域有重要应用价值的有机高性能纤维。本文综述了国内外PBO纤维的发展历程、纤维的性能,重点介绍了制备高分子量PBO聚合物和纺制高性能PBO纤维的关键技术和先进工艺,提供了改善PBO纤维界面粘结性能、压缩性能和光老化稳定性能的不同技术途径。结果表明:PBO聚合只有多种因素包括单体、工艺、设备等同时优化才能获得高分子量的PBO聚合物,利用双螺杆挤出机同时完成聚合和液晶纺丝成型是工业化连续生产高性能PBO纤维的先进技术路线;通过在PBO大分子链上引入离子基团或双羟基能显著提高PBO纤维与环氧树脂的界面粘结强度,双羟基的存在能使PBO大分子链间建立氢建相互作用从而也提高了PBO纤维的压缩性能,双羟基单体特有的紫外吸收性能更是有效地改善了PBO纤维的光稳定性;在PBO聚合时添加光吸收剂,或在PBO纤维表面涂覆聚酰亚胺都是改善PBO纤维光稳定性的有效方法。     

复合溶胶-凝胶法改善PBO纤维的光稳定性

分别以钛酸正丁酯(C_(16)H_(36)O_4Ti)、醋酸(CH_3COOH)、盐酸(HCl)、丙基三甲氧基硅烷(KH560)、苯基三甲氧基硅烷(Ph-TMS)、甲醇(CH_3OH)和去离子水为原料,氨水(NH_3·H_2O)为催化剂,采用溶胶-凝胶法和复合溶胶-凝胶法分别涂覆制备防老化聚亚苯基苯并二噁唑(PBO)纤维。通过粒度分析验证了纳米溶胶的成功制备,通过EDS能谱、SEM扫描电镜、接触角测定等手段分析测试PBO纤维表面的化学组成与物理性能,验证防老化PBO纤维的制备。以拉伸强度测试、SEM扫描电镜和表面接触角表征PBO纤维的防老化性能。结果表明:在氙灯耐气候试验箱经历130 h的老化后,与未经过涂覆的PBO原纤相比,采用纳米TiO_2水溶胶-凝胶法涂覆的PBO纤维拉伸强度保持率只提高了5%,利用纳米有机硅溶胶-凝胶法涂覆的PBO纤维拉伸强度保持率可提高10%,而经过纳米TiO_2和有机硅复合溶胶-凝胶法涂覆的PBO纤维,拉伸强度保持率提高了27%,且老化后的纤维表面保持得非常完整。     

复合溶胶-凝胶法改善PBO纤维的光稳定性

分别以钛酸正丁酯(C16H36O4Ti)、醋酸(CH3COOH)、盐酸(HCl)、丙基三甲氧基硅烷(KH560)、苯基三甲氧基硅烷(Ph-TMS)、甲醇(CH3OH)和去离子水(H2O)为原料,氨水(NH3·H2O)为催化剂,分别采用溶胶-凝胶法和复合溶胶-凝胶法涂覆制备防老化聚亚苯基苯并二唑(PBO)纤维。通过粒度分析验证了纳米溶胶的成功制备,通过EDS能谱、SEM扫描电镜、接触角测定等分析测试PBO纤维表面的化学组成与物理性能,验证防老化PBO纤维的成功制备。以拉伸强度测试、SEM扫描电镜和表面接触角表征PBO纤维的防老化性能。结果表明:在氙灯耐气候试验箱经历130h的老化后,与未经过涂覆的PBO原纤相比,采用纳米TiO2水溶胶-凝胶法涂覆的PBO纤维拉伸强度保持率只提高了5%,利用纳米有机硅溶胶-凝胶法涂覆的PBO纤维拉伸强度保持率可提高10%,而经过纳米TiO2和有机硅溶胶-凝胶法涂覆的PBO纤维,拉伸强度保持率提高了27%,且老化后的纤维表面保持得非常完整。     

An analysis of deformation process on poly‐p‐phenylenebenzobisoxazole fiber and a structural study of the new high‐modulus type PBO HM+ fiber

This study is concerned with fiber structure of new high‐modulus type PBO fiber. Crystal modulus and molecular orientation change with stress was surveyed. Standard‐modulus type PBO (AS) fiber has hysteresis effect to applied stress while high‐modulus type PBO (HM) fiber shows reversible change. In order to raise actual PBO fiber modulus higher, nonaqueous coagulation process was adopted with conventional heat treatment. The fiber (HM+) so made gives 360 GPa in the Young's modulus and an absence of small‐angle X‐ray scattering pattern that is characteristic for aqueous‐coagulated PBO fiber with heat treatment (Zylon™ HM). The crystal structure form and crystal size for the HM+ fiber are the same as those of the HM fiber. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1605–1611, 2000     

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.     

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.     

Poly(p-Phenylenebenzobisoxazole) fiber with polyphenylene sulfide pendent groups

Poly(p-phenylenebenzobisoxazole) (PBO) fiber with polyphenylene sulfide (PPS) pendent groups was made to improve PBO fiber compressive strength by crosslinking. PPS moieties allowed the polymeric network to crosslink at heat-treatment temperatures at which PBO does not thermally degrade. PBO-PPS fiber heat-treated for 30 s at 600°C did not dissolve or break up in methanesulfonic acid. Compressive strength of crosslinked fiber was about 20% better than that of unmodified PBO fiber. In another experiment, 10 mol % of 2,5-diphenylsulfideterephthalic acid was incorporated into PBO fiber. The side chain of one phenyl sulfide unit was too short to enhance crosslinking, and the fiber had about the same compressive strength as unmodified PBO fiber. © 1995 John Wiley & Sons, Inc.     

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     

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.     

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.