界面结合对GF/PDCPD复合材料性能的影响

界面结合性能对制备性能优异的复合材料具有重要意义。通过对双环戊二烯（DCPD）与玻璃纤维（GF）的浸润性进行研究，将其与等效环氧树脂比较，开发了一种与玻璃纤维具有较好结合性的DCPD树脂，用其制备出一种综合性能优异的玻璃纤维增强PDCPD基复合材料。通过动态接触角、90?拉伸强度和层间剪切强度实验，测定了不同树脂与玻璃纤维之间的粘附力，提供了玻璃纤维与不同树脂界面性能差异。结果表明，SCB-600 DCPD树脂与玻璃纤维的结合性较优，动态接触角为60.35??0.3?，90?拉伸强度为(42.3?1.6) MPa，层间剪切强度为(61.3?3.2) MPa，与1564环氧树脂相当。进一步优化了DCPD树脂质量分数，当树脂质量分数为30%?2%时，SCB-600 DCPD复合材料具有相对最优的力学性能，材料拉伸强度为(1180.1?4.1) MPa，弯曲强度为(1060.4?4.6) MPa，缺口冲击强度为(145.3?4.8) KJ/m2。其弯曲和拉伸强度与玻璃纤维增强环氧树脂基复合材料的性能基本相当，但缺口冲击强度优于1564环氧树脂。     

淀粉纳米晶对玻璃纤维的表面改性研究

采用自制的淀粉纳米晶(SNC)对玻璃纤维进行表面处理,增加其与环氧树脂基体的界面剪切强度(IFSS)。研究了处理方式、处理时间、SNC乙醇分散液浓度、热处理温度等工艺参数对SNC在玻璃纤维表面沉积情况的影响,以及对改性玻璃纤维与环氧树脂的界面性能的影响规律。采用扫描电子显微镜、单纤维强力仪对处理前后玻璃纤维进行表征,并采用微脱粘法测试玻璃纤维与环氧树脂的界面粘结情况。结果表明,当重力静置处理时间24 h,SNC乙醇分散液浓度为1 g/100 m L时,SNC在玻璃纤维表面均匀沉积,且能显著提高玻璃纤维与环氧树脂的IFSS,为27.29 MPa,较未处理的纤维增加29.3%。150℃热处理4 h后,X射线光电子能谱结果显示SNC与玻璃纤维形成化学键合,进一步增加纤维与环氧树脂的界面粘结,IFSS值达到32.30 MPa,较未处理的纤维增加53%,且纤维的拉伸强度得到较好的维持。     

Tensile behavior of glass‐fiber‐filled polyacetal: Influence of the functional groups of polymer matrices

We investigated the tensile behavior of glass‐fiber‐filled polyacetal [i.e., polyoxymethylene (POM)], focusing on the mutual influence of the functional groups in the POM matrices and the glass binder system. The different POM matrices were compounded with three kinds of glass fibers (20 wt %) treated with different glass binders, namely, epoxy resin, thermoplastic polyurethane (TPU), and a mixture of TPU and epoxy resin. A good correlation between the tensile strength and elongation at break was observed, regardless of the difference in the glass binders. The composites based on the modified POM matrix, which had both a carboxyl end group and a hydroxyl end group, improved the tensile properties noticeably in comparison with those based on the normal POM matrix. The composites were strengthened with an increase in the concentration of the functional groups. The results of scanning electron microscopy observations indicated that the fractured surfaces of a specimen having maximum tensile strength and elongation exhibited cohesion of the modified POM on the surfaces of the glass fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

The Study of Reactive Functional Groups in Adhesive Bonding at the Aramid-Epoxy Interface

In polymeric composites, reactive functional groups on the fiber surface are assumed to enhance the mechanical strength of the fiber-matrix interface greatly by forming covalent bonds with the matrix. To test this assumption, we sought to promote covalent bonding at the aramid fiber-epoxy matrix interface by attaching flexible reactive pendent groups to the fiber surface. Other factors that could affect interfacial adhesion were kept constant, i.e., surface energy and surface topography. Quantitative analysis showed a pendent group attachment level of 1.5 to 4.5 groups per 100 Ų of fiber surface, a level that agrees well with the theoretical amount. Surprisingly, in adhesive performance tests, the presence of these reactive pendent groups did not improve the fiber-matrix interface strength. Specific chemical tests for covalent bond formation between the terminal amine of the pendent group and the epoxy molecule showed that covalent bonding did not occur, thus explaining the unexpected lack of improvement in adhesive performance.     

Chemical Bonding and Physical Interaction by Attached Chains at the Fiber-Matrix Interface

Molecular chains with different chemical structures were attached to the surface of aramid engineering fiber, and their effect on the fiber's adhesion to epoxy matrix was measured. Adhesive performance increases up to 65% were achieved, depending on the structure of the attached chains. Increases were attributed to chemical bonding between the terminal reactive group of the chain and the epoxide molecule used in the matrix, and to a length-related physical interaction between the chain and epoxy matrix.     

芳纶纤维增强树脂基复合材料的界面粘结性能研究

为了改善芳纶纤维增强树脂基复合材料的界面粘结性能,从树脂基体入手,依据相似相容原理和芳纶的结构特点,合成出新型热固性树脂(AFR–T)用作芳纶复合材料的基体,以未经表面处理的芳纶作增强材料,采用热压成型法制备了AFR–T/芳纶纤维复合材料,并通过测定溶度参数、接触角、线膨胀系数、层间剪切强度(ILSS)和横向拉伸强度等方法研究了复合材料的界面粘结性能。结果表明,AFR–T树脂浇注体与芳纶的溶度参数相近,AFR–T树脂溶液在芳纶纸表面的接触角为36.9°,小于环氧树脂(EP)溶液与芳纶纸的接触角(53.2°),说明AFR–T树脂对芳纶的浸润性优于EP;AFR–T/芳纶纤维复合材料的ILSS和横向拉伸强度为73.0 MPa和25.3 MPa,分别比EP/芳纶纤维复合材料提高了25.9%和32.5%,这表明AFR–T树脂与芳纶纤维之间的浸润性和界面粘结性能较好。     

Mechanical properties of poly(styrene‐co‐acrylonitrile)‐modified epoxy resin/glass fiber composites

Poly(styrene‐co‐acylonitrile) was used to modify diglycedyl ether of bisphenol‐A type epoxy resin cured with diamino diphenyl sulfone and the modified epoxy resin was used as the matrix for fiber‐reinforced composites (FRPs) to get improved mechanical properties. E‐glass fiber was used as fiber reinforcement. The tensile, flexural, and impact properties of the blends and composites were investigated. The blends exhibited considerable improvement in mechanical properties. The scanning electron micrographs of the fractured surfaces of the blends and tensile fractured surfaces of the composites were also analyzed. The micrographs showed the influence of morphology on the properties of blends. Results showed that the mechanical properties of glass FRPs increased gradually upon fiber loading. Predictive models were applied using various equations to compare the mechanical data obtained theoretically and experimentally. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

碳纤维表面性能对界面黏结强度的影响浅析

为了解碳纤维表面性能对纤维-树脂界面黏结强度的影响,使用扫描电镜、原子力显微镜与X射线光电子能谱仪(XPS),对国产T-300级碳纤维、台丽TC36S碳纤维、东丽T700S碳纤维的表面进行物理与化学表征,得出:国产碳纤维与TC36S碳纤维表面形貌相近,而T700S表面比较光滑;XPS定量分析技术表明3种碳纤维表面的活性差异较大,碳纤维与树脂的界面黏结强度随纤维粗糙度和表面活性官能团而变化。     

Effects of chain lengths,molecular orientation,and functional groups of thiols adsorbed onto CF surface on interfacial properties of CF/epoxy composites

In this article, a new treatment method based on molecular self‐assembly on carbon fiber (CF) surface was proposed for obtaining a controlled interface between CF and epoxy matrix in composite system. To form the controlled interfacial region, the surfaces of CF were first metallized by electroless Ag plating, then were reacted with a series of thiols (alkanethiols, aromatic thiol, and heterocyclic thiol) to form self‐assembly (SA) films, which further reacted with epoxy resin to generate a strong adhesion interface. The structure and composition of untreated and treated CF surface were investigated by surface‐enhanced Raman scattering spectroscopy (SERS) and X‐ray photoelectron spectroscopy (XPS), respectively. SERS study showed that thiols chemisorbed on Ag‐plated CF in the form of thiolate species via the strong S? Ag coordinative bond. Moreover, adsorbate orientation of thiols SA films on Ag‐plated CF surfaces was revealed on the basis of SERS selection rules. The XPS study further confirmed the well organized alignment and the chemisorption of thiols. To understand the interfacial adhesion mechanism, the interfacial shear strength of CF/epoxy microcomposites was evaluated by the microbond technique. The results showed that among the parameters such as chain lengths, molecular orientation, and types of functional groups, the chemical nature of functional groups is most important for the improvement of interfacial properties in CF/epoxy composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of Fiber Surface Modification on the Mechanical Performance of Isora-Polyester Composites

This paper reports the effect of chemical treatment on the mechanical properties of a natural fiber, isora, as reinforcement in unsaturated polyester resin. Isora fiber is separated from the bark of the Helicteres isora plant by a retting process. The short isora fiber surface was modified chemically by acetylation, benzoylation, silane and triton treatments to bring about improved interfacial interaction between the fiber and the polyester matrix. The modified surfaces were characterized by IR spectroscopy and SEM. The SEM studies were carried out to investigate the fiber surface morphology, fiber pull-out and fiber-polyester interface bonding. They showed the changes occuring on the fiber surface during chemical treatment. Properties like tensile strength, flexural strength and impact strength have been studied. The chemical modification of fiber improved fiber/matrix interaction as evidenced by the enhanced tensile and flexural properties. The lower impact properties of the composites, except triton-treated fiber composite, further point to the improved fiber/matrix adhesion, compared to the untreated fiber composites.     

The effect of hydroxyl‐terminated polybutadiene‐grafted carbon fiber on the impact performance of carbon fiber–epoxy resin composites

Carbon fiber (CF) containing 1.4 and 2.1 mmol/g of —COOH and —OH groups, respectively, was functionalized by using an excess of tolylene‐2,4‐diisocyanate. The NCO‐modified CF was submitted to a graft reaction with hydroxyl‐terminated polybutadiene (HTPB). The HTPB‐grafted carbon fiber was employed as reinforcing agent for epoxy resin‐based composites. The presence of the flexible HTPB at the interface between the fiber and the matrix resulted in a substantial improvement on impact strength. Additional improvement on toughness was achieved by using epoxy matrix containing dispersed phase of HTPB. The composite morphology was also studied by scanning electron microscopy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1424–1431, 1999     

Surface modification and physical properties of various UHMWPE‐fiber‐reinforced modified epoxy composites

Two surface modification methods—plasma surface treatment and chemical agent treatment—were used to investigate their effects on the surface properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE) fibers. In the analyses, performed using electron spectroscopy for chemical analysis, changes in weight, and scanning electron microscope observations, demonstrated that the two fiber‐surface‐modified composites formed between UHMWPE fiber and epoxy matrix exhibited improved interfacial adhesion and slight improvements in tensile strengths, but notable decreases in elongation, relative to those properties of the composites reinforced with the untreated UHMWPE fibers. In addition, three kinds of epoxy resins—neat DGEBA, polyurethane‐crosslinked DGEBA, and BHHBP‐DGEBA—were used as resin matrices to examine the tensile and elongation properties of their UHMWPE fiber‐reinforced composites. From stress/strain measurements and scanning electron microscope observations, the resin matrix improved the tensile strength apparently, but did not affect the elongation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 655–665, 2007     

Chemical modification of apricot kernel shell waste and its effect on phenolic novolac epoxy composites

Apricot kernel is one of the most abundant types of agro-waste in the eastern Anatolia regions of Turkey. In this study, apricot kernel shells (AKShs) were chemically modified using levulinic acid (LA) for the first time, and their potential for developing biobased composites was evaluated. Phenol novolac epoxy resin was used as matrix owing to its high thermal and superior adhesion properties. Shell treatments to improve interfacial bonding were carried out using alkali, acetic acid, and LA. These treatments were aimed at improving the mechanical properties, wettability, and bonding of the composites. Moreover, these treatments could prevent the deterioration of the fiber/matrix interface (hydrophilic and hydrophobic effect) and mitigate damage to the fiber during production, which is one of the main reasons for the reduced strength of the composites. The thermal characteristics, crystallinity index, chemical composition, and surface morphology of the untreated and chemically modified AKShs and composites were studied by thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy, respectively. In addition, the composites were analyzed in detail using mechanical tests and contact angle measurements. The chemical treatment using LA resulted in composites with superior mechanical behavior.     

Effect of silane‐coupling agents on interfacial properties of CF/PI composites

In this article, to form a structure‐controlled interface, carbon fiber (CF) surfaces were first activated by plasma technique and then hydroxylated by LiAlH₄ treatment, and then were reacted with a suit of silane‐coupling agents terminated with desired functional groups to form thin films, which further reacted with polyimide (PI) resin to generate a strong adhesion interface. The morphology, structure, and composition of CF surfaces before and after treatment were investigated by atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS), respectively. The results of FTIR and XPS analysis showed that silane‐coupling agents were successfully chemisorbed onto the CF surfaces by the hydrolysis and condensation reactions. The interfacial shear strength of the CF/PI microcomposites was evaluated by the microbond technique. The results showed that the types of the interfacial functional groups, especially the vinyl end groups in vinyltriethoxysilane (VS), which can react with PI resin, had very significant influence on the improvement of the interfacial adhesion properties of composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Improvement of adhesion of Kevlar fiber to epoxy by chemical modification

Kevlar 149 fibers were surface-modified by chlorosulfonation and subsequent reaction of -SO₂O with some reagents (e.g. glycine, water, ethylenediamine, and 2-butanol) to improve the adhesion to epoxy resin. The mechanical properties and surface topography of the modified fibers were investigated at different reaction times and reagent concentrations. The surface functional groups introduced into the surface of the fibers were identified by X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectroscopy (SIMS). The interfacial shear strength (IFSS) between the fibers and epoxy resin was measured by the microbond test. The results showed that the IFSS was markedly improved (by a factor of 2.25) by the chlorosulfonation/glycine treatment and that the fiber strength was not affected. Scanning electron microscopy (SEM) was also used to study the surface topography of fibers pulled from the epoxy resin. Furthermore, energy dispersive X-ray (EDX) spectroscopy was used to qualitatively examine the amount of sulfur in the fiber surfaces and in the fracture surfaces of fibers from microbond pull-out specimens. The results of EDX examination were consistent with a change of the fracture mode from the interface between the fiber and the epoxy resin to a location within the fiber and/or epoxy resin as observed by SEM.     

The influence of pre-bond surface treatment over the reliability of steel epoxy/glass composites bonded joints

A main objective of present research is to consider adhesive bonding as a novel maintenance and repairing damaged section trend for fluid transporting tubes. Nowadays, applying glass fiber reinforced epoxy composite patches (GFRECPs) is considered as an alternative rapid and affordable repair system instead of traditional techniques such as removing strained sections. The main problem with repairing metal pipes using GFRECPs is low strength of adhesion between GFRECPs and a steel substrate. To make adhesion strong enough, it is necessary to excite the intrinsic adhesion forces such as dipoles across the interface which consequently increases a bonding strength due to Van der Waals forces; but secondary forces activation depends on surface regulation levels. In fact, providing a surface with a suitable roughness and increased pureness without any polluters is a key parameter achieving a highly resistant GFRECPs-steel adhesion. To do so, samples were prepared using the SiC paper up to 100, 220, 500 and polished to investigate the effect of different roughness levels in the range of 90.77±1.81 to 2.97±0.05 nm. The surfaces, interface features and bonding strength were characterized applying the atomic force microscope (AFM), water contact angle measurements, FE-SEM, single lap shear (SLS) and T-peel (90°) tests. The results revealed that the highest adhesion strength could be achieved at the polished substrate.     

The influence of silane coupling agent composition on the surface characterization of fiber and on fiber-matrix interfacial shear strength

It is well known that the fiber-matrix interface in many composites has a profound influence on composite performance. The objective of this study is to understand the influence of composition and concentration of coupling agent on interface strength by coating E-glass fibers with solutions containing a mixture of hydrolyzed propyl trimethoxysilane (PTMS) and n -aminopropyl trimethoxysilane (APS). The failure behavior and strength of the fiber-matrix interface were assessed by the single-fiber fragmentation test (SFFT), while the structure of silane coupling agent was studied in terms of its thickness by ellipsometry, its morphology by atomic force microscopy, its chemical composition by diffuse reflectance infrared Fourier transform (DRIFT), and its wettability by contact angle measurement. Deposition of 4.5 ‐ 10 m 3 mol/L solution of coupling agent in water resulted in a heterogeneous surface with irregular morphology. The SFFT results suggest that the amount of adhesion between the glass fiber and epoxy is dependent not only on the type of coupling agent but also on the composition of the coupling agent mixture. As the concentration of APS in the mixture increased, the extent of interfacial bonding between the fiber and matrix increased and the mode of failure changed. For the APS coated glass epoxy system, matrix cracks were formed perpendicular to the fiber axis in addition to a sheath of debonded interface region along the fiber axis.     

Novel application of chitosan: ameliorative effect of homogeneous and floccular chitosan on the interfacial property of carbon fiber/epoxy resin composites

A novel homogeneous floccular chitosan was directly grafted onto carbon fiber surface by a simple and controllable method. Scanning electron microscopy (SEM), single fiber strengths and interlaminar shear strength (ILSS) have been applied to characterize the fiber and the interface bonding. Compared with raw carbon fibers, the chitosan-treated ones demonstrate significant increases in the surface roughness and wettability. Particularly, about 21.21% increase in the mechanical properties of composites was obtained, which is attributed to good adhesion between functional carbon fiber and resin matrix in the interlaminar regions, as revealed by fracture surfaces.     

Kevlar纤维的表面改性研究

采用甲苯-2,4-二异氰酸酯(TDI)和环氧树脂(EP)混合制得的表面改性剂对Kevlar纤维进行表面接枝处理,利用扫描电子显微镜观察Kevlar纤维改性前后的表面形貌及改性Kevlar纤维与弹性体间剥离界面的破坏形貌,用衰减全反射傅里叶变换红外光谱仪分析Kevlar纤维改性前后表面化学基团的变化,研究了改性效果和机理。结果表明,TDI和EP发生了化学反应,改性剂可在Kevlar纤维表面引入活性基团,从而显著改善了Kevlar纤维与聚合物基体之间的界面粘合状态。     

Toughened epoxy resin matrix for a membrane shell by wet filament winding

A toughened epoxy resin matrix was obtained with a reactive toughening agent and methyl hexahydrophthalic anhydride as a curing agent. The mechanical properties of the modified epoxy resin and its glass‐fiber‐reinforced composites were investigated systematically. The modified epoxy resin matrix possessed many good properties, including a high flexural strength (138 MPa), high elongation at break (5.2%), low viscosity, long pot life at room temperature, and good water resistance. In addition, the glass‐fiber‐reinforced composites showed a high strength conversion ratio of the glass fiber (86.7%) and good fatigue resistance. The results demonstrated that the modified epoxy resin matrix is very suitable for applications in reverse osmosis membrane shell products fabricated with wet filament winding for water treatment. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009