碳纤维增强树脂基复合材料的界面

从碳纤维、树脂基体、界面3个层次对碳纤维增强树脂基复合材料的界面研究进行了综述,重点介绍了碳纤维表面特性表征及改性方法、树脂基体特性及改性方法和界面分析表征手段,由此提出了纤维/树脂界面的研究路线,简要分析了复合材料界面研究的前景与趋势。为了实现纤维/树脂界面的良好匹配,充分发挥碳纤维复合材料的性能优势,需完善界面表征手段、明确界面微观性能与复合材料宏观性能的关系、深化研究界面对复合材料湿热性能及失效模式的影响等。     

高强型聚酰亚胺纤维增强热塑性树脂基复合材料防弹性能研究

采用S35高强型聚酰亚胺(PI)纤维作为增强体，热塑性树脂作为基体，采用热压工艺制备了织物结构和正交单向无纬(UD)结构复合材料靶板，通过弹道极限速度测试和背部变形测试，研究了增强体结构和界面结合强度对PI纤维增强热塑性树脂基复合材料防弹性能的影响。结果表明：高强型聚酰亚胺纤维表现出了优异的防弹性能；UD结构靶板更适用于防铅芯弹；织物结构靶板更适用于防破片；当界面剥离强度由5.45N/cm提高到26.44N/cm时，剥离后界面处的纤维表面形貌的破坏程度逐渐增加。当侵彻体为5.6g铅芯弹时，随着界面剥离强度的提高，复合材料靶板的防弹性能呈现出先提高后降低的趋势；并且靶板的背部变形逐渐减小，进一步证明了界面结合强度对复合材料靶板防弹性能的影响。     

上浆剂对碳纤维复合材料界面结合影响的研究进展

简要介绍了各种热固性和热塑性上浆剂,重点是综述上浆剂对碳纤维复合材料界面性能的影响及其相关机理。上浆剂对碳纤维复合材料界面的影响依赖于在纤维表面的附着量,上浆剂对碳纤维/树脂界面的增强机理主要为,通过碳纤维表面附着的上浆层,提高与基体树脂间的相容性。     

芳纶纤维复合材料界面粘结性能研究

为了改善芳纶纤维复合材料的界面粘结性能,从自制树脂基体入手,针对芳纶纤维的结构特点,合成了一种新型树脂(AFR)作为基体,制备了芳纶/AFR复合材料.通过宏观力学、微观力学以及接触角测试等方法研究了AFR树脂与芳纶纤维之间的界面粘结性能.结果表明:AFR树脂对芳纶纤维的浸润性好,单丝拔出强度高,复合材料的横向拉伸强度及层间剪切强度高,这说明芳纶纤维与AFR树脂之间具有良好的界面粘结性能.     

多壁碳纳米管界面传感器及其在纤维缠绕压力容器原位监测中的应用

研发了基于多壁碳纳米管（MWCNT）界面传感器的多功能复合材料,并研究了其在纤维缠绕压力容器健康监测中的应用。首先考察了该界面传感器在复杂环境中的可靠性,分析了MWCNT对纤维/基体界面层间剪切强度的影响,得到了植入MWCNT界面传感器的复合材料在不同水温下吸水特性;随后研究了基于MWCNT界面传感器的纤维/基体界面原位监测和损伤修复,分析了利用该方法原位监测、修复热塑性复合材料界面损伤的可行性;最后将MWCNT界面传感器植入到纤维缠绕压力容器中,并考察了该压力容器在水压疲劳、水压爆破两类载荷下的原位监测效果。研究结果表明:植入MWCNT界面传感器可提高复合材料纤维/基体的界面层间剪切强度,且在一定水温范围内,植入MWCNT的界面强度下降率更低;通过在复合材料中植入MWCNT界面传感器,可实现对纤维增强热塑性树脂复合材料界面的原位监测和修复;利用该方法也能够原位监测纤维缠绕压力容器的工作状态,进而获取其界面损伤信息。      

芳纶复合材料的界面粘结

为改善芳纶纤维增强树脂基复合材料中界面粘结强度,本研究用Mctowo.Takayanagi——化学处理法,对芳纶1414纤维进行表面处理.并依据红外光谱分析(IR),元素分析(E.A.),XPS能谱分析等近似估价芳纶1414纤维表面导入约88mol%接技率的E-51环氧化合物.用单纤维拉拔实验法直接测定芳纶1414纤维/环氧树脂基体体系的界面剪切强度.实验结果表明,芳纶1414纤维经表面环氧接技化处理后,可较明显地提高界面剪切强度而对纤维拉伸强度的降低较小.树脂基体性能对界面剪切强度的影响较显著.通过电子显微镜(SEM)观察被拔出纤维及树脂孔穴的破坏形貌,解析界面破坏机理.     

连续纤维增强PPESK树脂基复合材料的界面性能

用SEM观察了复合材料的微观断面结构,用横向拉伸强度和层间剪切强度表征玻璃纤维(GF)、T700碳纤维(CF)、芳纶纤维(F-12)增强PPESK树脂基复合材料的界面性能,研究了界面性能对三种复合材料耐湿热性能的影响.结果表明,T700/PPESK和F-12/PPESK复合材料的界面粘接性能均优于GF/PPESK复合体系.三种纤维复合材料的破坏机理不同:玻璃纤维发生纤维与树脂的界面脱粘破坏,碳纤维复合材料在破坏时,树脂与纤维并没有完全脱粘,破坏发生在树脂内;而芳纶纤维复合材料的破坏总伴随着纤维本身横向的撕裂破坏.三种复合材料体系均具有较低的吸湿率和良好的耐湿热性能,T700/PPESK复合材料在湿热条件下的性能保持率最高.     

玻璃纤维增强热塑性有机复合材料界面强度及其对材料力学性能的影响

本文研究了 BK-10玻璃纤维增强聚甲基丙烯酸甲酯和聚碳酸酯两种热塑性有机基复合材料中纤维与基体界面强度的测量、控制及其对复合材料性能的影响。用有机硅烷耦联剂涂覆纤维表面可以提高纤维与基体的界面强度并相应提高复合材料的力学性能。实验发现四种基体纤维界面破坏形式分别存在于界面强度强和弱的韧性和脆性基体复合材料体系中。选用折光率相匹配的基体和纤维,适当控制制备工艺可以制备出光学透明的复合材料。     

热塑性树脂基复合材料用碳纤维上浆剂研究进展

与高性能热塑性树脂不匹配、耐热性偏低的传统上浆剂越发难以满足热塑性树脂基复合材料快速发展与应用的需求,开发面向热塑性树脂基复合材料的碳纤维上浆剂具有重要意义。本文对上浆剂的主要作用效果、上浆剂与增强材料和基体树脂间的相互作用、热塑性树脂基复合材料用碳纤维上浆剂的主要特点进行了概述;对聚酰胺、聚氨酯、聚芳醚、聚酰亚胺及其他类型上浆剂的研究进展进行了重点论述,结合各体系的性能特点和主要问题,梳理了不同热塑性树脂基复合材料用碳纤维上浆剂的改性途径及近年来在各大生产企业中的研发应用情况,分析和阐明了各自的作用机制与发展现状,对热塑性树脂基复合材料用碳纤维上浆剂的未来趋势进行了展望,并给出了发展建议。      

界面对树脂基复合材料拉-拉疲劳性能影响研究

采用正交试验的方法,通过改变基体树脂和增强材料的种类以及采用偶联剂对界面改性的方法,研究了界面对树脂基复合材料拉-拉疲劳性能的影响.结果表明:基体树脂和增强材料之间的匹配性对复合材料疲劳性能具有重大的影响.通过采用偶联剂对界面进行改性处理可以在一定程度上提高纤维增强复合材料的疲劳性能.     

Thermoplastic–epoxy interactions and their potential applications in joining composite structures – A review

This paper presents a literature survey on the theoretical backgrounds and the past research efforts in relation to the interactions between certain thermoplastics and epoxies, and their applications in polymer blending, epoxy toughening and composite joining. The main objectives are to understand the possible mechanisms of interfacial adhesion between thermoplastic and thermoset polymers, and also to explore the feasible approaches to improve interfacial adhesion for the purposes of joining fibre reinforced polymer (FRP) composite structures by fusion bonding. Further, it is expected that the review would provide some visions to the potential applications of the thermoplastic–thermoset interfacial interactions for the quick assembly of composite structures in cost-effective manufacturing of composite structures, through the uses of the technologies, such as thermoset composite fusion bonding, welding of thermoplastic composites with thermoset composites, and thermoplastic article attachment on thermoset composites.     

Leaky guided wave propagation along imperfectly bonded fibers in composite materials

Leaky guided modes propagating along embedded fibers in a composite material can be used for characterizing the fiber-matrix interface. This principle can be applied to real composites containing small-diameter fibers by using laser interferometric detection of very fine lateral resolution on the order of a few microns. The main purpose of this paper is to develop the analytical tools needed to assess the sensitivity of guided wave inspection to interface properties in composite materials. Typically, the sound velocity is much lower in the matrix than in the fiber and the guided modes are strongly attenuated by leaking their energy into the matrix as they propagate. As a result, the velocity of the lowest-order axisymmetric longitudinal mode decreases while its attenuation increases with increasing interfacial stiffness between the fiber and the matrix. It is shown that loose fibers can be readily identified from early signals produced by fast guided modes. In the case of a well-bonded fiber-matrix interface, these guided modes are slowed down and strongly attenuated by the loading of the matrix depending on the fiber diameter and the interfacial stiffness of the interface. Interestingly, the relative difference between the well-bonded and free fibers is greater at low frequencies. Therefore, good sensitivity to the sought interfacial stiffness can be achieved at a few MHz, i.e., when the fiber diameter is still much smaller than the acoustic wavelength. Our analytical results show that the leaky guided mode technique is mainly sensitive to the transverse interfacial stiffness of the fiber-matrix interface. At typical ultrasonic frequencies between 1 and 20 MHz, the technique works best in the 10¹¹–10¹³ N/m³ interfacial stiffness range which is one or two orders of magnitude lower than the optimal sensitivity range of the more conventional bulk velocity and reflection methods.     

Mechanism of fracture of short glass fibre-reinforced polyamide thermoplastic

The mechanism of fracture of short glass fibre-reinforced polyamide 6.6 thermoplastic was studied by means of optical and electron microscopy and acoustic emission methods. It was found that there were three stages in the failure, i.e. initiation of the interfacial cracks at fibre ends, propagation of the interfacial cracks along fibre sides, and propagation of the crack into the matrix leading to the failure of the composite. On the fracture surface, fibres were almost pulled-out from the matrix, not broken. The close correspondence between the crack initiation and propagation and the amplitude of AE signals was observed. The AE signals of lower amplitude occurring under a relatively low stress were considered to be made in association with the initiation and propagation of the interfacial cracks. The AE signals of higher amplitude observed prior to the failure of the composite were considered to be made in association with the occurrence of the matrix cracks. Furthermore, in order to analyse the effect of the stress state in the composite on crack occurrence and propagation, the stress levels in matrix, fibre and interface were estimated for the composite stressed to the failure stress. The calculation was based on the equivalent inclusion method proposed by Eshelby and on an assumption of a perfect bond between the matrix and the fibres. The result was found to be consistent with the mechanism of the fracture, the occurrence of the interfacial cracking in the initial stage and the matrix cracking in the final one.     

Inverse/genetic method and its application in identification of mechanical parameters of interface in composite

In this paper, an inverse/genetic method for interfacial parameter identification is developed. The interfacial parameter identification process can be converted into an inverse approximation problem using the method which includes finite element method and genetic algorithms for searching solution. Based on the interfacial failure information obtained from experiment, the inverse approximation procedure identifying interfacial parameters is constructed by taking the advantages of genetic algorithms over traditional gradient-based search methods. The study indicates that a good prediction with relatively high accuracy of the interfacial parameters of real composite can be achieved with the proposed method. It seems that the proposed method is promising in solving a wide range of parameter identification problems in robust way.     

镁基复合材料界面调控研究进展EI北大核心

界面是影响镁基复合材料综合性能的关键因素,如何进行界面调控一直是镁基复合材料的研究热点。本文围绕镁基复合材料三种界面结构类型(共格界面、半共格界面和非共格界面),针对影响界面性能的两个关键问题(界面润湿性和界面反应),综述了界面优化方案的研究进展,提出了实现良好界面结合的界面结构设计与调控准则:良好润湿性与轻微界面反应。针对镁基复合材料的界面性能提升,可以考虑添加稀土元素,起到净化界面、改善润湿性的作用;根据工程需要选择基体和增强体,得到某方面性能优异的复合材料;开发新的增强体表面涂层,充分提高界面结合能力;通过第一性原理等计算模拟方法,深入探究界面结构与界面性能之间的关系。     

Mechanical Properties of Thermoplastic and Thermoset Composites Reinforced with 3D Biaxial Warp-knitted Fabrics

In this study, two types of thermoplastic matrices (low melting point polyethylene terephthalate (LPET) fiber and polypropylene (PP) fiber) and glass fiber/epoxy resin/multi-walled carbon nanotubes (MWCNTs) were used to fabricate the thermoplastic and thermoset composite materials with 3D biaxial warp-knitted fabrics. Thermoplastic and thermoset composites were fabricated using hot-press and resin transfer molding (RTM) methods. The fabricated samples were tested with tensile and three-point flexural tests. In thermoplastic composites, samples in the 90° direction and LPET matrix showed the best tensile and flexural properties with an improvement of 39 and 21% tensile modulus and strength, 16 and 8% flexural modulus and strength compared to the PP samples in the same direction. In thermoset composites, samples in the 90° direction and MWCNTs showed the best improvement of the flexural modulus and strength with 97 and 58% compared to the samples without MWCNTs. This improvement can most likely be attributed to an increase in interfacial adhesion due to the presence of the carbon nanotubes.     

单纤维界面强度光弹性实验和理论研究

利用光弹性实验和有限元计算两种方法对单丝拔出复合材料模型的界面剪应力进行了研究。从计算和实验两个方面证明,当在纤维自由端施加一轴向拉力后,在单丝与基体界面的埋入端附近将出现剪应力的最大值。然后,沿着单丝的埋入方向,剪应力迅速降低,在界面区的中间趋于最小值,并且基本稳定不变。由此证明,单丝增强复合材料中界面的应力传递主要集中在单丝的埋入端附近,并且在这一区域最先达到危险应力,发生界面的脱胶破坏,引起整个试件的失效。     

玻璃纤维织物/聚苯硫醚粉叠层模塑工艺与性能

研究聚苯硫醚(PPS)树脂粉与玻璃纤维织物(GF)叠层模塑(粉末工艺)制复合材料的工艺与性能。测试各种工艺条件制GF/PPS层板的弯曲力学性能、动态力学性能,用扫描电镜(SEM)探查树脂对纤维的浸渍及纤维/基体的界面粘合情况。SEM分析结果表明,粉末工艺制得的PPS基复合材料呈现高的力学性能,是由于树脂对纤维的均匀浸渍和良好的纤维/基体的界面粘合。熔前热压、高温成型、退火处理是粉末工艺制高质量GF/PPS层板的工艺要点。      

UHMWPE纤维增强LDPE复合材料的界面形态研究

为实现聚乙烯单聚合物复合材料(PE SPC)的嵌件注射成型,研究基体与增强体间的界面非常关键.本文采用超高分子量聚乙烯(UHMWPE)纤维增强低密度聚乙烯(LDPE)基体,对纤维和基体进行了差示扫描量热仪测试,在偏光显微镜下模拟了基体与纤维的复合过程,研究不同因素对复合材料界面结晶形态的影响.根据DSC确定了UHMWPE和LDPE复合的温度范围在110.98~147.14℃;合适的温度和剪切作用都有利于界面横晶的产生,从而使基体和纤维产生更好的粘结,提高复合材料的力学性能;温度比剪切的影响更大,注射温度设置在125~135℃可在保证纤维与基体复合的情况下不破坏纤维的增强作用;纤维丝之间会相互影响界面结晶形态,部分界面有横晶产生,说明在实际注射成型过程中纤维束或纤维布的结构对基体渗透和界面形成有较大影响.     

界面应力传递重新分析及Cohesive模型参数的确定

在经典剪滞理论中引入双线性cohesive模型表征纤维/基体之间的非理想界面,重新分析了纤维增强复合材料中的应力传递机理,得到了考虑界面因素的应力分布。用上述结果解释了单丝段裂实验过程中的现象,讨论了界面参数和材料性能对应力分布的影响。基于上述理论,建立了用cohesive单元表征界面的模拟单丝段裂实验的三维有限元模型,结合单丝段裂实验结果,提出了一种估测cohesive界面刚度参数的新方法。数值和理论分析结果与实验结果对比,吻合良好,可以为材料的界面性能分析和材料设计提供参考依据。