PET缝编碳纤维织物冷等离子体处理对RTM成型浸润性的影响

RTM工艺成型过程中树脂对纤维增强体的浸润是重要的一环,浸润不好将导致RTM成型复合材料中产生缺陷,这将降低复合材料的界面性能。本文作者采用冷等离子体技术对PET缝编碳纤维织物进行表面处理,并采用AFM对处理前后的碳纤维表面形貌进行了分析。实验结果表明:冷等离子体处理可以使碳纤维表面活性提高,从而改善RTM工艺成型过程树脂对PET缝编碳纤维织物的浸润性,进而改善RTM成型复合材料的界面性能。     

碳纤维三维立体织物中纤维表面改性的均一化研究

采用阳极氧化法对碳纤维三维织物进行了表面处理。通过复合材料的界面强度、抗冲击性能和抗压性能,研究了阳极氧化处理工艺参数对碳纤维三维织物复合材料性能的影响。实验结果表明该方法不仅能对三维织物表层的碳纤维进行表面改性, 而且能深入织物内部, 实现对碳纤维三维织物的均一化处理, 从而使碳纤维三维织物/酚醛复合材料的界面强度均得到大幅度提高, 复合材的整体性能得到改善。      

冷等离子体处理对涤纶纤维表面性能的影响

采用冷等离子体技术处理涂纶纤维,利用ESCA分析了冷等离子体处理前后的纤维表面元素组成,官能团类型的变化,通过比较处理前后浸润性,涂纶纤维／环氧复合材料的层间剪切强度,研究了冷等离子处理对涤纶纤维表面性质的影响,结果表明：绦纶纤维经冷等离子处理后表面含氧的极性基团增加,纤维表面的浸润性显著改善,涤纶纤维／环氧复合材料界面性能增强。     

Preparation and characterization of three-dimensional braided carbon/Kevlar/epoxy hybrid composites

Though unidirectional, short, and laminated hybrid composites have been extensively investigated because of their wider range of properties than non-hybrid composites, literature on three-dimensional (3-D) braided hybrid composites is very limited. In this work, Kevlar fibers were hybridized to carbon fibers to prepare 3-D carbon/Kevlar/epoxy composites with various carbon to Kevlar fiber volume ratios in an attempt to find alternative materials for osteosynthesis devices. The flexural, shear, and impact properties of the 3-D braided hybrid composites were measured in order to investigate the effect of carbon to Kevlar ratio and evaluate hybrid effects. In addition, residual flexural strength was tested for the impacted samples and the damage tolerance was assessed. Our experimental results revealed the existence of positive hybrid effects on the shear and flexural strengths flexural strain for the 3-D braided composites. The absorbed energy and flexural strength retention of the 3-D braided hybrid composites were found to decrease with relative carbon fiber content. It was shown that hybridizing ductile 3-D braided Kevlar fabric with stiff carbon fabric could result in the hybrid composites with flexural strength comparable to the all-carbon composite and impact damage tolerance superior to the all-Kevlar composite.     

Effect of oxygen plasma-treated carbon fibers on the tribological behavior of oil-absorbed carbon/epoxy woven composites

In this study, woven type carbon fibers were plasma-treated using oxygen gas, and the effect of the plasma treatment on tribological behavior of oil-absorbed carbon/epoxy woven composites was investigated. Chemical changes on the surface of the woven carbon fibers due to oxygen plasma treatment were determined by XPS analysis. Ball-on-disk wear tests were performed on untreated and plasma-treated carbon/epoxy woven composites that were fully oil absorbed. It was found that carbonyl functional groups were created on the carbon fibers due to oxygen-plasma treatment. In addition, the friction coefficient and wear rate of the plasma-treated carbon/epoxy composites were lower than that of untreated carbon/epoxy composites. SEM examination of the worn surface showed that the improved wear properties of the plasma-treated carbon/epoxy composites were attributed to enhanced adhesive strength, caused by the carbonyl functional groups between the carbon fibers and epoxy.     

碳密封涂覆光纤在编织复合材料中的应用

碳密封涂覆光纤由于具有良好的强度性能和抗疲劳能力,已应用于海底光缆、军用制导光纤以及苛刻环境下的光纤传感系统中。本文作者研究了碳密封涂覆光纤在三维碳/环氧编织复合材料中的应用。将该光纤成功地编入编织复合材料试件并成型。对该光纤在编织前、后以及成型后的光学性能进行了测试。设计了使用碳密封涂覆光纤的偏振式光纤传感器,并用其对试件处于弯曲受力状态的情况进行了测试。     

Mechanical performance of hybrid bismaleimide composites reinforced with three-dimensional braided carbon and Kevlar fabrics

Short, unidirectional and laminated hybrid composites have been extensively investigated. However, very limited work has been conducted on three-dimensional (3-D) braided hybrid composites. In this work, 3-D braided carbon and Kevlar fibres were hybridized to reinforce a bismaleimide (BMI) resin. The purpose of this paper was to investigate the effect of carbon to Kevlar ratio on such mechanical properties as load–displacement behaviour, flexural strength and modulus, shear strength, and impact properties. The effect of surface treatment of hybrid fabrics on the flexural properties was also determined. Experimental results showed that the flexural strength and modulus of the 3-D braided carbon/Kevlar/BMI composites increased with relative carbon fibre loading up to a carbon to Kevlar ratio of 3:2 and then dropped. Positive hybrid effects were observed for both flexural strength and modulus. The results presented in this work proved that hybridization with certain amount of ductile Kevlar fibre markedly promoted the shear strength, impact energy absorption characteristics and damage tolerance of the all-carbon composite, which is of importance for the 3-D braided composites to be used in bone fixations. Fracture surfaces and microstructures of various 3-D braided hybrid composites were analyzed to interpret the experimental findings.     

三维编织超高分子量聚乙烯纤维/碳纤维/环氧树脂混杂复合材料力学行为及混杂效应

采用复合处理工艺对三维混杂超高分子量聚乙烯纤维/碳纤维编织体进行表面处理, 通过RTM工艺制备了环氧树脂基混杂复合材料（UHMWPE/CF/ER）, 并研究了其力学性能及混杂效应。结果表明, 在纤维总体积分数一定的情况下, 随着超高分子量聚乙烯纤维/碳纤维混杂比的减小, 复合材料的弯曲强度、 弯曲模量及压缩强度增大, 而其纵向剪切强度及冲击韧性降低。三维编织混杂复合材料的断裂机制由混杂纤维的混杂比及其性质决定, 通过调节混杂比可实现对复合材料力学性能的有效调控。      

Effect of surface treatment of carbon fibers with gamma-ray radiation on mechanical performance of their composites

Gamma-ray radiation was used to surface treat PAN carbon fibers. The efficiency of gamma-ray radiation was compared with air oxidation in terms of variations in the surface structure of carbon fibers and the mechanical performance of their composites. It was observed that the composites reinforced with the gamma-radiated carbon fibers showed higher interfacial adhesion strength and thus better flexural and shear properties than the composites reinforced with air-treated fibers. The observed higher content of carboxyl group on the surface of the gamma-radiated carbon fibers is likely to be responsible for the stronger fiber-matrix bonding. It is concluded that gamma-ray radiation is an effective approach of tailoring surface properties of carbon fibers.     

沥青基炭纤维γ-射线改性对炭/ 炭复合材料力学性能的影响

为了提高沥青基炭纤维表面活性, 采用γ-射线辐照对沥青基炭纤维表面改性。用AFM、XPS 研究了γ-射线辐照改性后沥青基炭纤维表面结构的变化, 用浸润仪测定了改性前后沥青基炭纤维表面能的变化。研究了γ-射线辐照沥青基炭纤维对炭/ 炭复合材料力学性能的影响, 并用SEM 分析了炭/ 炭复合材料断口形貌。结果表明,γ-射线辐照使炭纤维表面含氧官能团和表面粗糙度增加, 提高了沥青基炭纤维的表面能; 降低了炭/ 炭复合材料孔隙率, 提高了炭/ 炭复合材料力学性能。     

基于面-内胞模型的三维四向编织复合材料渐进损伤数值模拟

为了准确预测三维四向编织复合材料的纵向拉伸力学性能,对编织复合材料的面胞和内胞细观实体模型进行参数化建模,面胞模型考虑了纱线空间轨迹的偏移和横截面的挤压变形。用体素网格离散模型并施加合适的边界条件,将各组分材料的损伤模型编入到有限元分析软件ABAQUS用户定义材料子程序UMAT中。分别对内编织角为30°和45°的三维四向碳纤维/环氧树脂编织复合材料的面-内胞模型进行数值分析,经体积加权平均获得不同厚度编织复合材料试件的纵向拉伸模量和强度,通过统计具有相同破坏模式的积分点数量研究复合材料的渐进损伤过程。结果表明:基于面-内胞模型预测三维四向编织复合材料的纵向拉伸力学性能与试验值吻合良好,损伤分析结果合理地反映了面胞和内胞的渐进损伤过程。      

碳纤维在高温下的结构、性能演变研究

针对碳纤维在碳/碳烧蚀防热复合材料中应用的基础问题,论述了不同碳纤维结构、成分、表面特征,及其力学性能和热物理性能的高温演变规律,揭示了碳纤维灰分含量对碳纤维力学性能和热氧化性能的影响。确定了在碳/碳复合材料复合成型过程中,碳纤维结构受基体碳影响的变化规律和碳纤维表面特征对碳/碳材料宏观力学性能的影响。阐明了碳/碳复合材料中碳纤维的力学性能对纤维发生折断烧蚀的阻碍作用和通过控制碳/碳成型最高温度实现提高性能的途径。     

碳纤维在电子束辐射过程中对树脂基复合材料界面性能的影响

采用XPS和Raman分析了电子束辐射对碳纤维表面性质的影响，研究了碳纤维与基体树脂之间的不充分接触对电子束固化复合材料层间剪切强度的影响，同时分析了碳纤维表面吸附的水分，碳纤维与基体树脂之间的空隙率和碳纤维表面在碳酸氢铵电解液中进行阳极氧化处理后对电子束固化复合材料界面性能的影响，分析了碳纤维表面在电子束辐射过程中与树脂基体的作用机理。     

三维四向编织复合材料弹性性能的理论预测

在对三维四步(1×1)编织物结构分析的基础上,进一步完善了基元、面元和角元的三细胞模型,使修正后的模型实现了空间上的几何连续性,较为真实地模拟了编织预制件的纤维走向。然后,基于修正后的三细胞模型并采用刚度平均法预测了三维编织复合材料的弹性性能,通过与现有实验结果的比较,验证了该模型的适用性。      

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。     

Processing of hybrid wood plastic composite reinforced with short PET fibers

Poly(ethylene terephthalate) (PET) fibers (virgin, waste, and mixed) were incorporated in the composite poly(methyl methacrylate) (PMMA)–wood. Hybrid composite panels were prepared by pressure molding. Toluene-2,4-diisocyanate (TDI) and (3-mercaptopropyl)trimethoxysilane (MPTMS) were used as cross-linking bonding agents for modification of wood fibers. Influence of cross-linking bonding agents, structure, and composition of PET fibers was examined by studying thermomechanical properties as well as moisture absorption. Moisture absorption was lower for composites with bonding agents. Mechanical testing revealed that the addition of PET fibers drastically enhances properties of the composites. Covalent and hydrogen bonds formed with the addition of bonding agents have also improved mechanical properties compared to the untreated composites.     

碳纤维/乙烯基酯树脂拉挤复合材料界面性能研究

对PAN基碳纤维在线热氧化表面处理,分析了处理前后碳纤维的表面形貌,通过拉挤成型工艺制备出碳纤维/乙烯基酯树脂复合材料。对拉挤复合材料的微观结构观察以及力学性能测试表明:碳纤维经表面处理后表面粗糙度增加,与乙烯基酯树脂的界面粘结性明显改善,复合材料的力学性能尤其是层间剪切强度得到显著提高。对不同界面性能的碳纤维复合材料进行动态热机械分析(DMTA),认为界面性能的改善可降低损耗模量,提高复合材料的耐疲劳性能。     

三维编织碳纤维/环氧树脂复合材料横向压缩性质的温度效应

采用实验和有限元方法,研究了三维编织碳纤维/环氧树脂复合材料在低温场（20、0、-50、-100℃）中横向压缩性质温度效应。研究结果表明：温度对碳纤维/环氧树脂横向压缩模量、屈服应力及切向模量均有不同程度影响。三维编织碳纤维/环氧树脂复合材料横向压缩后,试样表面形貌受温度影响显著。低温场中,表面鳞纹现象减弱,且纱线-树脂间界面出现开裂。温度降低导致碳纤维/环氧树脂内部产生热应力。热应力对碳纤维/环氧树脂力学性能影响有限,不是温度效应的主导因素。基体性质随温度变化是三维编织碳纤维/环氧树脂复合材料横向压缩性质温度效应的主要机制。     

纳米CaCO_3/PET短纤维/聚丙烯复合材料的制备及性能

制备了纳米CaCO3/聚丙烯、聚对苯二甲酸乙二酯(PET)短纤维/聚丙烯、CaCO3/PET短纤维/聚丙烯复合材料。分别测试了复合材料的力学性能,结果发现,与纳米CaCO3/聚丙烯、PET短纤维/聚丙烯两相复合材料相比,三相复合材料的力学性能尤其是冲击性能有明显的提高。采用X射线衍射(XRD)、动态力学分析(DMA)、电子扫描(SEM)系统研究了复合材料的增强机理,结果发现,在三相复合材料中,纳米CaCO3的加入明显提高了PET短纤维与聚丙烯基体界面之间的作用力和相容性,同时纳米CaCO3与PET短纤维的协同效应诱导了聚丙烯β晶的生成。     

Effects of anodic oxidation treatment for three dimensional carbon fibre braided fabric on properties of its composite

Abstract

An anodic oxidation treatment method is developed in this paper which is capable of modifying the surfaces of carbon fibres in three-dimensional 3D braided fabrics conveniently and uniformly. The results on the utilisation of this method in the surface treatment of 3D carbon fibre braided fabrics are presented. The effects of anodic oxidation treatment of 3D fabrics on the properties of phenolic resin composites are analysed and discussed. By appropriate treatment, the interfacial shear strength and compressive strength may be improved by 20 and 59.3 respectively. As far as the impact properties of the composites are concerned, the crack initiation energy was increased and the crack propagation energy decreased. Concerning ablative properties of the composites, the linear ablative rate was decreased by 10.7 and the maximum temperature of the underside of the ablative section was reduced by 2.7.