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.     

空气介质阻挡放电对超高分子量聚乙烯纤维表面性能及粘结力的影响研究

利用空气介质阻挡放电(DBD)等离子体对超高分子量聚乙烯(UHMWPE)纤维进行表面改性处理研究以提高纤维表面的润湿和粘结性能.分别研究了等离子体处理时间及电压对UHMWPE纤维拉伸断裂强力、接触角、表面形貌、表面化学成分和粘结性能等的影响规律.SEM分析结果表明,空气DBD等离子体处理后UHMWPE纤维表面出现垂直于纤维轴向分布的凹坑和裂纹,使得纤维表面粗糙度显著增加.XPS分析表明空气DBD处理后纤维表面碳元素含量显著下降;同时氧元素和氮元素的含量均较处理前增加,但氧元素含量增加的幅度显著高于氮元素.XPS分峰结果表明等离子体处理后UHMWPE纤维纤维表面C—O/C—N基团含量显著增加,同时出现了C O和O—C O这2种新的含氧官能团.同时,接触角及和与环氧树脂之间的界面剪切力(IFSS)测试结果表明DBD等离子体处理后UHMWPE纤维表面润湿性能和粘结力均产生显著提高,且随着等离子体处理时间或电压的增加,UHMWPE纤维的表面润湿性能和粘结力均呈现先上升后下降的趋势.空气DBD等离子体处理对UHMWPE纤维的力学性能影响较小,当处理电压低于200 V,处理时间小于100 s,纤维强力下降比率小于5.2%.     

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...     

辉光放电等离子体对聚丙烯纤维的表面改性

在对电晕、介质阻挡放电、γ射线辐射接枝对化纤改性的简要介绍基础上，重点论述了辉光放电等离子体对聚丙烯纤维的改性。并按等离子体技术的发展过程，对低压和常压辉光放电等离子体对聚丙烯纤维与织物改性的特点、原理及发展前景进行了扼要综述，指出常压辉光放电等离子体是一种很有潜力的表面改性技术。     

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。     

聚(对亚苯基-1,3,4-噁二唑)纤维表面氟化处理研究

采用氟气(F2)对聚(对亚苯基-1,3,4-噁二唑)(p-POD)纤维表面进行直接氟化处理.衰减全反射红外光谱(ATR-FTIR)和表面电子能谱(XPS)的结果显示,通过直接氟化处理,p-POD纤维较易与F2发生反应,表面大分子链上引入了大量C—F键,表面氟元素含量高达28.2%,且F原子以—CF/C O、—CFH及—CF2形式存在,表明在表面氟化过程中,既有取代反应,也有加成反应.热失重(TGA)结果表明氟化前后p-POD纤维的耐高温性能没有受到影响,X射线衍射图谱(XRD)表明氟化后纤维的聚集态有序性略微增加.氟化前后纤维的断裂强度基本无变化,在体积分数为20%的硫酸溶液中的人工加速酸老化条件下,氟化后纤维在老化120 h后的断裂强力保留率在80%以上,相比氟化前的纤维提高了约90%,即耐酸性得到明显改善.推测表面氟化处理改善p-POD纤维耐酸性的机理是氟化后p-POD纤维表面N元素含量降低,抑制了溶剂化过程;纤维表面致密程度得到提高以及F原子与酸液形成氢键,从而阻止噁二唑环的质子化,延缓了老化进程.     

低温等离子体处理天然纤维的ESR研究

低温等离子体表面改质技术,近年来在纤维加工领域的应用引起广泛注目。纤维、高分子材料经低温等离子体处理,在纤维基质中生成自由基。这些自由基同活性原子团一样,其中不稳定的自由基迅速重新结合,而稳定的自由基就残留在纤维基质中。本文研究了天然纤维棉、麻、羊毛和蚕丝分别在O_2、N_2、Ar、CO及CF_4气体中的低温等离子体表面改质处理,用ESR光谱测定了纤维基质中生成的自由基的相对强度,并讨论了热处理对自由基稳定性的影响。     

生物医用高分子纤维材料

综述了医用的高分子纤维材料及其改性的方法。医用高分子纤维材料包括天然高分子及合成高分子两大类。其中包括不可降解的及可降解的高分子纤维材料。利用聚合物共混、交联、纤维表面改性,如等离子体处理、纤维表面化学反应及聚合物的表面接枝等物理化学方法可对医用纤维进行改性,改善纤维的力学性能、生物相容性,并使之具有细胞粘附性,利于组织的生长。     

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。     

聚二甲基硅氧烷表面亲水性的研究

为了使聚二甲基硅氧烷(PDMS)具有较稳定的亲水性表面,利用氧等离子体技术对PDMS表面进行处理。研究了氧等离子体处理PDMS表面的时间、功率、氧气流量等参数对表面亲水性的影响,通过接触角测量和X-射线光电子能谱(XPS)对处理效果进行了评价。实验表明:PDMS经氧等离子体处理后放置700 h的表面接触角为72°,达到了持久改性的目的;XPS分析表明,表面亲水性的改善主要是由于表面极性成分的增加,最后讨论了氧等离子体处理PDMS表面的改性机理。     

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 for plasma‐treated aramid fiber‐reinforced poly(phthalazinone ether sulfone ketone) composite and fiber surface aging effects

Interfacial adhesion between the fiber and the matrix in a composite is a primary factor for stress transfer from the matrix to the fiber. In this study, oxygen plasma treatment method was applied to modify the fiber surface for improving interfacial adhesion of aramid fiber‐reinforced poly(phthalazinone ether sulfone ketone) (PPESK) composite. Composite interfacial adhesion properties were determined by interlaminar shear strength (ILSS) using a short‐beam bending test. The composite interfacial adhesion mechanism was discussed by SEM. The changes of chemical composition and wettability for plasma‐treated fiber surfaces stored in air as long as 10 days were investigated by XPS and dynamic contact angle analysis (DCAA), respectively. Results indicated that oxygen plasma treatment was an effective method for improving interfacial adhesion; plasma‐treated fiber surface suffered aging effects during storage in air. Copyright © 2008 John Wiley & Sons, Ltd.     

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.     

Highly improved mechanical strength of aramid paper composite via a bridge of cellulose nanofiber

A novel aramid paper composite based on pretreated meta-aramid fiber via the addition of cellulose nanofiber (CNF) was fabricated, and the mechanical strength and interfacial strength of the aramid paper composite were investigated. The results indicated that modified fibers showed higher roughness and more available hydrophilic groups. Besides, compared with the pristine aramid paper, it turned out that the tensile index, tear index and interlayer bonding strength of the paper composites with CNF increased by 2.04 times, 2.36 times and 3 times, respectively. In addition, tensile energy absorption (TEA) was also improved by an increment of 99.7% with 20 wt% CNF. These apparent evidences can be accounted for the following mechanisms. On the one hand, enhanced mechanical properties of aramid paper composite were derived from the strong hydrogen bonding or dipole–dipole coupling interaction between aramid fiber and CNF. On the other hand, significant reinforcement of interlayer bonding strength can be attributed to the pivotal bonding bridge and filling agent between aramid chopped fibers (ACFs) and fibrid, which could improve interfacial adhesion of paper sheet. The thin film structure like “spider web” or “silk” from SEM images indicated the CNF was used as a bridge actually.     

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.     

The surface modification of carbon fiber for thermoplastic HDPE composites

The interfacial adhesion strength between the fiber and the matrix greatly affects the properties of the carbon fiber (CF)–reinforced composite. The presence of surface functional groups on the fiber and changes in surface roughness were determined by X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy. The effect of surface modification of CF on the mechanical properties and tribological properties of the composites is enhanced. The performance has been significantly improved. SEM analysis showed that modification had a positive effect on the interface between fiber and matrix. In the paper, the method of CF modification and the treatment of enhanced high-density polyethylene have simple and effective characteristics, which can be widely used and have guiding significance for industrial production.     

Effects of plasma treatment of carbon fibers on interfacial properties of BMI resin composites

High performance continuous fiber surface modification by inductively coupled RF plasma (ICP) and dielectric barrier discharge (DBD) low temperature plasma were conducted. X-ray photoelectron spectroscopy (XPS) and other analytical testing methods systematically studied plasma treatment time, discharge power, discharge pressure, etc, on fiber surface state, surface composition, and surface shape changes in the appearance and wetting properties. The results show that after plasma treatment the surface of the fiber is grafted with a large number of polar functional groups such as carboxyl groups and hydroxyl groups. The surface roughness increases, the surface free energy increases, and the fiber wetting property is significantly improved, resulting in improvement in interlaminar shear strength (ILSS) between the fiber and the resin matrix. Finally, the surfaces of the fibers and its relationship with interfacial properties of fiber reinforced bismaleimide composites are also discussed.     

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.     

Effect of carbon fiber surface functionality on the moisture absorption behavior of carbon fiber/epoxy resin composites

Polyacrylonitrile (PAN)‐based carbon fibers were electrochemically oxidized in aqueous ammonium bicarbonate with increasing current density. The electrochemical treatment led to significant changes of surface physical properties and chemical structures. The oxidized fibers showed much cleaner surfaces and increased levels of oxygen functionalities. However, it was found that there was no correlation between surface roughness and the fiber/resin bond strength, i.e. mechanical interlocking did not play a major role in fiber/resin adhesion. Increases in surface chemical functionality resulted in improved fiber/resin bonding and increased interlaminar shear strength (ILSS) of carbon fiber reinforced epoxy composites. The relationship between fiber surface functionality and the hydrothermal aging behavior of carbon fiber/epoxy composites was investigated. The existence of free volume resulted from poor wetting of carbon fibers by the epoxy matrix and the interfacial chemical structure were the governing factors in the moisture absorption process of carbon fiber/epoxy composites. Copyright © 2016 John Wiley & Sons, Ltd.     

Plasma treatment of carbon fiber on the tribological property of polyimide composite

The effect of different ratios of carbon fiber (CF) reinforcing polyimide (PI) and surface treatment of CF on the microstructure and wear resistance of surface layers was studied. The increase of CF content led to a gradual increase in the Interlaminar shear strength (ILSS) values, and the maximum ILSS value arises when the CF content is 15 vol%, with an improvement of 13.45% compared to virgin CF composites. The increased interfacial adhesion could be contributed mainly to the presence of branched PI at the interface region. SEM of the worn surface confirms that the plasma treatment efficiently improves the interfacial adhesion of CF/PI composite. Copyright © 2017 John Wiley & Sons, Ltd.