含碳纳米管的PEI纤维膜对环氧树脂力学性能的影响

采用高压静电纺丝法制备了含多壁碳纳米管(MWCNTs)的聚醚酰亚胺(PEI)纳米纤维取向薄膜, 用SEM和TEM观察其微观形貌。将PEI纳米纤维薄膜铺放于环氧树脂中, 通过实验测试其冲击和拉伸性能。结果表明, 含MWCNTs的PEI纳米纤维膜对环氧树脂具有良好的增韧效果。Ⅰ型层间断裂韧性(G_IC)测试表明, 用含质量分数3%活性碳纳米管(a-MWCNTs)的PEI纤维膜对T700碳纤维/环氧树脂复合材料进行层间增韧能够明显改善其层间断裂韧性。     

氧化石墨烯-碳纳米管复合膜层间增韧碳纤维/环氧树脂复合材料

碳纤维增强树脂基复合材料层合板结构的层间性能一直是材料的性能短板,本文利用氧化石墨烯(GO)和碳纳米管(CNT)设计制备了具有一定渗透性和树脂浸润性的复合膜,采用层间增韧方法,制备了GO-CNT复合膜改性碳纤维/环氧树脂(CF/EP)复合材料,通过张开型Ⅰ型层间断裂韧性(G_ⅠC)与滑移型Ⅱ型层间断裂韧性(G_ⅡC)对GO-CNT-CF/EP复合材料的层间韧性进行了研究,并结合复合材料的破坏微观形貌和损伤/破坏特征分析了GO-CNT复合膜对复合材料的层间增韧效果及增韧机制。结果表明：GO与CNT质量比为3∶7时制备的复合膜具有良好的成膜工艺性和树脂浸润性,EP与GO-CNT复合膜的接触角远低于其与纯GO膜的接触角,并且GO与CNT结构中的羟基、羧基、环氧基等含氧基团增加了它们与EP的物理亲和性和化学作用,有利于复合材料层间GO-CNT/EP微区结构的强韧化。GO-CNT复合膜对复合材料的张开型层间断裂韧性G_ⅠC没有增强效果,甚至复合材料的G_ⅠC值还发生了轻微下降。而GO-CNT复合膜对复合材料的滑移型层...     

含碳纳米管的PEI纤维膜对环氧树脂力学性能的影响

采用高压静电纺丝法制备了含多壁碳纳米管(MWCNTs)的聚醚酰亚胺(PEI)纳米纤维取向薄膜,用SEM和TEM观察其微观形貌.将PEI纳米纤维薄膜铺放于环氧树脂中,通过实验测试其冲击和拉伸性能.结果表明,含MWCNTs的PEI纳米纤维膜对环氧树脂具有良好的增韧效果.Ⅰ型层间断裂韧性(GIC)测试表明,用含质量分数3％活性碳纳米管(a-MWCNTs)的PEI纤维膜对T700碳纤维/环氧树脂复合材料进行层间增韧能够明显改善其层间断裂韧性.     

MWCNTs对碳纤维非褶皱无纺布/环氧层合板力学性能的影响

将羧基化多壁碳纳米管(MWCNTs)添加到TDE85环氧树脂中,然后与碳纤维非褶皱无纺布(C-NCF)复合,制备成[0°/90°/+45°/-45°]_S层合板。采用三点弯曲、短梁剪切和单边切口弯曲测试方法以及动态力学性能分析方法,研究了不同含量的MWCNTs对层合板弯曲性能、层间剪切强度(ILSS)、Ⅱ型层间断裂韧性(G_ⅡC,以及玻璃态转变温度(T_g)的影响。并采用SEM对Ⅱ型试样的断面进行分析。结果表明,MWCNTs的加入显著提高了NCF层合板的力学性能。与空白试样相比,当MWCNTs在树脂中的质量分数为2.0%时,弯曲强度和模量分别提高了约26%和6%;当MWCNTs的质量分数为0.5%时,ILSS、G_ⅡC、T_g分别提高约14%、27%和14%。     

FeOOH纳米粒子协同聚偏氟乙烯电纺纤维膜插层增强碳纤维复合材料层间断裂韧性

为有效增强碳纤维/环氧树脂复合材料层压板(CF/EP)的层间断裂韧性,提出了一种纳米粒子协同纳米纤维膜插层改性方法.首先利用喷涂法将针状羟基氧化铁(FeOOH)纳米粒子均匀负载于碳纤维布表面,然后将制得的静电纺丝聚偏氟乙烯纳米纤维膜(PVDF)插入碳纤维布的层间,采用手工铺设-真空热压法制备了改性复合材料层压板PVDF...     

含碳纳米管上浆剂的制备及对碳纤维/环氧树脂复合材料界面的影响

首先采用"Friedel-Crafts"酰化反应制备羧基化多壁碳纳米管(MWCNTs)并将其与环氧树脂、丙酮混合制成含MWCNTs的上浆剂,然后用该上浆剂浸渍碳纤维制备碳纳米管/碳纤维多尺度增强纤维。采用扫描电镜研究了上浆处理对碳纤维表面形貌的影响,采用短臂梁剪切测试方法研究了含碳纳米管的上浆剂对碳纤维/环氧树脂复合材料层间剪切强度(ILSS)的影响。结果表明,碳纳米管在上浆剂中的分散状态直接影响纤维表面碳纳米管分布的均匀性;与未浸渍的碳纤维相比,含碳纳米管上浆剂浸渍后的碳纤维/环氧树脂复合材料的ILSS提高了34.33%。通过上浆剂红外光谱表征、纤维束表面浸润性测试及ILSS试样端口形貌的观察,分析了层间增韧机理。研究表明,碳纤维束表面浸润性的提高以及碳纤维/环氧树脂界面处化学键合作用增强,是ILSS提高的主要原因。     

碳纳米管/聚砜纳米纤维增强增韧环氧树脂的研究

利用静电纺丝技术制备了碳纳米管/聚砜复合纳米纤维.由于碳纳米管的增强作用、聚砜的增韧作用以及聚砜纳米纤维良好的相容性,使得该复合纳米纤维对环氧树脂基体能够同时起到增强和增韧效果.应用透射和扫描电子显微镜表征了碳纳米管/聚砜复合纳米纤维的直径分布,通过测试拉伸和冲击性能分析了复合纳米纤维对环氧树脂的增强和增韧作用,对断裂表面微观形貌进行了观察,并测试了添加复合纳米纤维的环氧树脂动态力学性能.与环氧树脂基体相比,含3wt%CNTs的复合纳米纤维增强增韧环氧树脂的拉伸强度和模量分别提高13.9%和14.2%,冲击强度提高18.3%.     

PEI纳米纤维层间增韧碳纤维环氧复合材料性能研究

基于聚醚酰亚胺优越的力学性能和纳米纤维膜高比表面积、高孔隙率的特性,利用气泡静电纺丝工艺制备不同厚度的纳米纤维膜改善碳纤维环氧复合材料的层间韧性。结果发现不同膜厚度增韧的双悬臂梁(DCB)试件的I型层间断裂值(GIC)均有所提高,特别是膜厚为0.058±0.007 mm时,层合板的增韧效果最好,比未增韧试件提高了114.55%。通过复合材料层间断裂界面的SEM照片证实了纳米纤维膜在界面处通过桥联约束效应及钉锚作用有效提高了复合材料的层间断裂韧性。     

聚砜纳米纤维膜增韧环氧树脂的反应诱导相分离过程研究

工程塑料改性环氧树脂基体的诱导相分离现象研究是了解其增韧机理的基础.通过相差显微镜,扫描电子显微镜以及同步辐射小角X光散射等方法,研究了聚砜纳米纤维膜增韧环氧树脂的反应诱导相分离过程.结果表明:该体系的相分离过程遵循的是成核-生长机理,形成海岛结构并且还是"原位"相分离,相分离后的聚砜微球沿着纳米纤维的"痕迹"有序排列.而且体系的相分离速率快于固化速率,相尺寸主要由相分离速率控制.其研究结果为进一步发展纳米纤维增韧碳纤维树脂基复合材料提供了基础数据.     

碳纤维表面改性及对其复合材料性能的影响

采用γ射线辐照法、电化学聚合法改性碳纤维表面,研究了以三缩四乙二醇为接枝单体,在不同的辐照剂量下辐照处理碳纤维,以及电化学聚合衣康酸改性碳纤维。利用扫描电子显微镜、X光电子能谱仪、电子万能试验机研究了处理前后的碳纤维的表面形貌、复合材料的断面形貌、表面化学组成及复合材料层间剪切强度(ILSS)的变化。研究结果表明,2种处理方法都能有效提高碳纤维表面活性,与环氧树脂的浸润性提高,复合材料断面纤维拔出明显减少。在200kGy的辐照剂量下处理得到的碳纤维与环氧树脂复合材料的ILSS的提高幅度最大,达到31.2%。同时经电聚合处理后的碳纤维与环氧树脂复合材料的ILSS的提高幅度要大于经γ射线辐照处理后的试样,达到40%。     

Novel carbon fiber/epoxy composite toughened by electrospun polysulfone nanofibers

Novel carbon fiber/epoxy composite toughened by electrospun polysulfone (PSF) nanofibers was prepared to enhance fracture toughness of the composite, and compared the morphology and toughness to those of composite toughened by PSF films prepared by solvent method. Polysulfone nanofibers with the average diameter of 230 nm were directly electrospun onto carbon fiber/epoxy prepregs to toughen the composite. SEM observations of the polysulfone nanofibers toughened composite revealed that polysulfone spheres with uneven sizes presented uniform dispersion through interleaves of the composite, which was different from those of composite toughened by PSF films. Mode I fracture toughness (G_IC) of the nanofibers toughened composite was 0.869 kJ/m² for 5.0 wt.% polysulfone nanofibers content, which was 140% and 280% higher than those of PSF films toughened and untoughened composite due to the uniform distribution of polysulfone spheres.     

Synchronous effects of multiscale reinforced and toughened CFRP composites by MWNTs-EP/PSF hybrid nanofibers with preferred orientation

MWNTs-EP/PSF (polysulfone) hybrid nanofibers with preferred orientation were directly electrospun onto carbon fiber/epoxy prepregs and interlaminar synchronously reinforced and toughened CFRP composites were successfully fabricated. With MWNTs-EP loading increasing, the oriented nanofibers were obtained accompanying with enhanced alignment of inner MWNTs-EP. Flexural properties and interlaminar shear strength of composites were improved with increasing MWNTs-EP loadings, whereas fracture toughness attained maximum at 10 wt% MWNTs-EP loading and then decreased. Based on these results, multiscale schematic modeling and mechanism schematic of hybrid nanofibers reinforced and toughened composites were suggested. Due to the preferred orientation of nanofibers, MWNTs-EP was inclined to align vertically to carbon fiber direction along the in-plane of interface layer. The proposed network structures, containing four correlative phases of MWNTs-EP/PSF sphere/carbon fiber/epoxy matrix, contributed to simultaneous improvement of strength and toughness of composites, which was realized by crack pinning, crack deflection, crack bridging and effective load transfer.     

结构化增韧层增韧RTM复合材料性能

从复合材料离位增韧思想出发,选用具有高孔隙率的尼龙无纺布(PNF)作为结构化增韧层,采用RTM工艺制备了PNF层间增韧改性的U3160碳纤维增强环氧3266树脂基复合材料(U3160-PNF/3266),并研究了其韧性相关性能和增韧机制。结果表明:U3160-PNF/3266复合材料层间仍保持其原有的结构形式,同时与层间树脂相互贯穿形成了一种非反应诱导相分离的双连续结构,并且这种双连续结构表现出显著的增韧效果。U3160-PNF/3266复合材料的Ⅰ型层间断裂韧性和Ⅱ型层间断裂韧性分别提高了1.1倍和1.4倍,冲击后压缩强度由212MPa提高到281MPa。     

电子束固化复合材料界面

电子束固化复合材料界面粘结性能较低是急待解决的问题。利用阳极氧化技术和偶联剂涂层对碳纤维表面进行处理。处理前后的碳纤维表面性能利用SEM、XPS和接触角测试方法进行分析,通过层间剪切强度表征电子束固化复合材料界面粘结性能,并且与热固化复合材料进行对比。结果表明: 当碳纤维在酸性电解液中进行阳极氧化时,有利于提高电子束固化复合材料界面粘合性能,在碱性电解液中进行阳极氧化时, 则导致较低界面粘接性能。阳极氧化与偶联剂双重增效作用能够提高电子束固化复合材料界面粘合性能。     

γ射线辐照对碳纤维表面接枝改性的影响

为提高碳纤维/环氧树脂复合材料的界面粘结性能, 采用γ射线共辐照接枝方法对碳纤维表面改性, 利用X光电子能谱仪(XPS)、 扫描电子显微镜(SEM)、 电子万能材料试验机, 研究了在缩乙二醇丙酮溶液和环氧氯丙烷丙酮溶液中经200 kGy剂量的γ射线辐照接枝后, 碳纤维的表面化学元素及官能团组成、 表面形貌、 复合材料剪切断面形貌及其层间剪切强度(ILSS)的变化。研究表明, 缩乙二醇类接枝液的接枝效果较理想, 碳纤维接枝率达7%; 辐照处理碳纤维表面O/C比值和含氧官能团含量增加, 以此制备的碳纤维/环氧复合材料的ILSS提高, 最大提高率达31.2%; 同时还发现辐照接枝后的碳纤维表面粗糙度增大。     

不同孔隙率CFRP层合板静态力学性能研究

为了研究孔隙率对织物碳纤维/环氧树脂复合材料层合板静态力学性能的影响规律,分别测量了孔隙率为0.33%至1.50%的CFRP层合板的弯曲强度和层间剪切强度,并进行有限元模拟.在适用于复合材料单向板的改进Hashin失效准则基础上,建立了适用于织物纤维增强复合材料静态力学强度的失效准则.通过引入复合材料基本强度参数预测不同孔隙率CFRP层合板的力学性能,结合刚度突然退化模型,采用ABAQUS软件建立了有限元模型.试验结果表明,随着孔隙率的增加,复合材料层合板的弯曲强度和层间剪切强度均呈下降趋势.有限元模型较为准确地预测了不同孔隙率织物碳纤维/环氧树脂复合材料层合板的弯曲强度和层间剪切强度.     

聚合物涂层对高模量碳纤维表面性能的影响

为改善碳纤维表面性能以及碳纤维/树脂复合材料的界面性能,对PAN基高模量碳纤维（HMCF）表面进行聚合物涂层处理。研究了不同潜伏性固化剂含量的聚合物涂层对HMCF表面以及碳纤维/树脂复合材料的界面性能的影响。IR分析表明,聚合物涂层与纤维或树脂基体发生了化学反应。扫描电镜和动态机械热分析的结果也说明,聚合物涂层能够提高...     

碳纤维表面结构对复合材料吸湿性能的影响

通过改变阳极氧化处理程度得到了具有不同表面结构的碳纤维, 然后将其与环氧树脂加工成碳纤维/树脂基复合材料, 研究了碳纤维的化学结构与湿热环境下复合材料吸湿之间的关系。结果显示: 阳极氧化处理后碳纤维表面的活性显著提高, 碳纤维表面含氧官能团的含量大幅增加, 尤其是-OH由处理前18.62%提高到处理后的34.84%。随着湿热处理条件的改变, 复合材料的吸湿机理也有所差异, 且温度是影响复合材料吸湿的重要因素。碳纤维表面活性越高, 复合材料达到吸湿平衡时的平衡吸湿量越大, 而平衡吸湿量的增加又会导致复合材料层间剪切强度(ILSS)下降幅度增大。     

Interlaminar shear behavior of unidirectional glass fiber (U)/random glass fiber (R)/epoxy hybrid and non-hybrid composite laminates

The interlaminar shear behavior of unidirectional glass fiber (U)/random glass fiber (R)/epoxy hybrid composites was studied with short beam shear bending test. Random glass fiber (R)/epoxy means chopped fiber composite having short discontinuous fiber randomly dispersed in epoxy matrix. The effect of stacking sequence and unidirectional glass fiber relative volume fraction (V_fU/V_fT) on the interlaminar shear strength (ILSS) of the manufactured composites has been investigated experimentally and theoretically. The laminates were fabricated by hand lay-up technique with 5 plies. Two non-hybrid composite laminates [R]₅ and [U]₅ were fabricated using the same fabrication technique for the comparison purpose. The average thickness of the manufactured laminates is 5.5 ± 0.2 mm and the total fiber volume fraction (V_fT) is 37%. Failure modes of all specimens were investigated. Experimental results indicated that the ILSS of [U]₅ is higher than those of hybrid and [R]₅ composite. Hybrid composites have higher ILSS than that of random composites. The stacking sequence and (V_fU/V_fT) ratio have a detectable effect on ILSS of the investigated composites.     

Interlaminar shear strength of SiC matrix composites reinforced by continuous fibers at 900 °C in air

To reveal the shear properties of SiC matrix composites, interlaminar shear strength (ILSS) of three kinds of silicon carbide matrix composites was investigated by compression of the double notched shear specimen (DNS) at 900 °C in air. The investigated composites included a woven plain carbon fiber reinforced silicon carbide composite (2D-C/SiC), a two-and-a-half-dimensional carbon fiber-reinforced silicon carbide composite (2.5D-C/SiC) and a woven plain silicon carbon fiber reinforced silicon carbide composite (2D-SiC/SiC). A scanning electron microscope was employed to observe the microstructure and fracture morphologies. It can be found that the fiber type and reinforcement architecture have significant impacts on the ILSS of the SiC matrix composites. Great anisotropy of ILSS can be found for 2.5D-C/SiC because of the different fracture resistance of the warp fibers. Larger ILSS can be obtained when the specimens was loaded along the weft direction. In addition, the SiC fibers could enhance the ILSS, compared with carbon fibers. The improvement is attributed to the higher oxidation resistance of SiC fibers and the similar thermal expansion coefficients between the matrix and the fibers.