碳纳米管/碳纤维/环氧树脂复合材料研究

制备了碳纳米管(CNTs)/碳纤维(CF)/环氧树脂(EP)三元复合材料。研究了CNTs含量对复合材料层间剪切强度、弯曲强度和弯曲模量的影响,并采用场发射扫描电镜分析了CNTs在基体树脂中的分散情况。结果表明:复合材料性能的变化源自于CNTs在基体树脂中的分散状态。当CNTs含量为0.2%(wt,下同)时,复合材料剪切强度和弯曲强度达到最大值,分别为99.2MPa和1811.4MPa,但其弯曲模量下降了8.7GPa。当CNTs添加量达到1%时,其弯曲模量达到135.9GPa,较未加入CNTs时提高了11.1%,层间剪切强度和弯曲强度分别降低了5.5MPa和359.5MPa。     

Influence of small amount of glass fibers on mechanical properties of discontinuous recycled carbon fiber-reinforced thermoplastics

The effect of residual contamination, such as glass fibers (GFs), on the application of discontinuous recycled carbon fibers (rCFs) is still unclear. In this study, GFs are used to substitute rCF at volume fractions (Vfs) of 0%, 1%, 2%, and 5% in carbon fiber paper-reinforced thermoplastics fabricated through a papermaking process. After an investigation with the three-point bending tests, the flexural modulus will not decrease when the GF content increased. Unlike the flexural modulus, the flexural strength decreased with an increase in the GF volume. In order to illustrate the effect of small amount of GF on flexural modulus, a modified rule of mixture (ROM) is used to derive a coefficient, Factor c₁, depicting the effect caused by discontinuous and randomly distributed reinforcement fibers. Furthermore, modified Halpin–Tsai model with Factor c₁ illustrated that the experiment results of flexural modulus is not decreased as fast as predicted results. Therefore, small amount of GF will not affect the application of rCF.     

炭纤维增强羟基磷灰石/聚乳酸复合生物材料的力学性能和体外降解性能

采用溶液共混法制备了炭纤维(CF)增强羟基磷灰石(HA)/聚乳酸(PLA)三元复合生物材料。研究了该复合材料的力学性能和体外降解性能。CF/HA/PLA复合材料具有优异的力学性能, 弯曲强度和弯曲模量均随着HA含量的增加先升高后降低, 存在一个峰值, 可分别达到430MPa和26GPa。在PBS模拟体液中降解3个月, 弯曲强度和弯曲模量分别下降到初始值的30%和36%。SEM照片显示, 降解是从复合材料的界面开始的, 降解3个月后, 界面结合处出现缝隙, 吸水率增加到5%, 质量损失只有1.6%。PBS模拟体液的pH值下降在0.1之内, 有利于骨折部位的愈合。实验结果表明, 该复合材料的机械性能满足骨折内固定材料技术指标的要求。      

Additive manufacturing of carbon fiber reinforced thermoplastic composites using fused deposition modeling

Additive manufacturing (AM) technologies have been successfully applied in various applications. Fused deposition modeling (FDM), one of the most popular AM techniques, is the most widely used method for fabricating thermoplastic parts those are mainly used as rapid prototypes for functional testing with advantages of low cost, minimal wastage, and ease of material change. Due to the intrinsically limited mechanical properties of pure thermoplastic materials, there is a critical need to improve mechanical properties for FDM-fabricated pure thermoplastic parts. One of the possible methods is adding reinforced materials (such as carbon fibers) into plastic materials to form thermoplastic matrix carbon fiber reinforced plastic (CFRP) composites those could be directly used in the actual application areas, such as aerospace, automotive, and wind energy. This paper is going to present FDM of thermoplastic matrix CFRP composites and test if adding carbon fiber (different content and length) can improve the mechanical properties of FDM-fabricated parts. The CFRP feedstock filaments were fabricated from plastic pellets and carbon fiber powders for FDM process. After FDM fabrication, effects on the tensile properties (including tensile strength, Young's modulus, toughness, yield strength, and ductility) and flexural properties (including flexural stress, flexural modulus, flexural toughness, and flexural yield strength) of specimens were experimentally investigated. In order to explore the parts fracture reasons during tensile and flexural tests, fracture interface of CFRP composite specimens after tensile testing and flexural testing was observed and analyzed using SEM micrograph.     

碳纤维-Ni/尼龙66复合材料的制备与性能表征

为制备低电阻率的尼龙66基复合材料,以碳纤维和镍粉(Ni)填充尼龙66制备碳纤维-Ni/尼龙66高导电复合材料。研究填料表面改性和含量对碳纤维-Ni/尼龙66复合材料导电性能和力学性能的影响。结果表明:KH550改性碳纤维和Ni有助于降低碳纤维-Ni/尼龙66复合材料的电阻率。碳纤维-Ni/尼龙66复合材料的电阻率随着碳纤维和Ni含量的增加而减小,且碳纤维和Ni填充尼龙66的导电逾渗阈值均为20wt%,此时制备的碳纤维-Ni/尼龙66复合材料的电阻率为455Ω·cm,熔融温度为202.2℃。碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度随着碳纤维或Ni含量的增加而先增大后减小。当Ni含量为20wt%时,碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度在碳纤维含量分别为20wt%和10wt%时达到最大值,分别为98MPa和70 MPa;当碳纤维含量为20wt%时,碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度则在Ni含量为30wt%和20wt%时达到最大值,分别为120 MPa和67 MPa。     

Recycled carbon fibre-reinforced polypropylene thermoplastic composites

Comingled carbon fibre (CF)/polypropylene (PP) yarns were produced from chopped recycled carbon fibres (reCF) (20 mm in length, 7-8 μm diameter) blended with matrix polypropylene staple fibres (60 mm in length, 28 μm diameter) using a modified carding and wrap spinning process. Microscopic analysis showed that more than 90% of the reCF were aligned along the yarn axis. Thermoplastic composite test specimens fabricated from the wrap-spun yarns had 15-27.7% reCF volume content. Similar to the yarn, greater than 90% of the reCF comprising each composite sample made, showed a parallel alignment with the axis of the test specimens. The average values obtained for tensile, and flexural strengths were 160 MPa and 154 MPa, respectively for composite specimens containing 27.7% reCF by volume. It was concluded that with such mechanical properties, thermoplastic composites made from recycled CF could be used as low cost materials for many non-structural applications.     

Preparation and mechanical properties of carbon fiber reinforced hydroxyapatite/polylactide biocomposites

A novel biocomposite of carbon fiber (CF) reinforced hydroxyapatite (HA)/polylactide (PLA) was prepared by hot pressing a prepreg which consisting of PLA, HA and CF. The prepreg was manufactured by solvent impregnation process. Polymer resin PLA dissolved with chloroform was mixed with HA. After reinforcement CF bundle was impregnated in the mixture, the solvent was dried completely and subsequently hot-pressed uniaxially under a pressure of 40 MPa at 170°C for 20 min. A study was carried out to investigate change in mechanical properties of CF/HA/PLA composites before and after degradation in vitro. The composites have excellent mechanical properties. A peak showed in flexural strength, flexural modulus and shear strength aspects, reaching up 430 MPa, 22 GPa, 212 MPa, respectively, as the HA content increased. Degraded in vitro for 3 months, the flexural strength and flexural modulus of the CF/HA/PLA fell 13.2% and 5.4%, respectively, while the shear strength of the CF/HA/PLA composites remains at the 190 MPa level. The SEM photos showed that there were gaps between the PLA matrix and CF after degradation. Water uptake increased to 5%, but the mass loss rate was only 1.6%. The pH values of the PBS dropped less than 0.1. That’s because the alkaline of HA neutralize the acid degrades from PLA, which can prevent the body from the acidity harm.     

热解碳含量对碳/碳-聚酰亚胺复合材料性能的影响EI北大核心

通过化学气相渗透和浸渍-固化成型工艺制备碳/碳-聚酰亚胺复合材料。首先采用化学气相渗透法对碳毡进行热解碳的沉积,制得热解碳含量分别在7.33%(质量分数,下同),14.55%,22.00%的多孔碳/碳坯体,再经过特定的浸渍-固化工艺,依次制得碳/碳-聚酰亚胺复合材料P1,P2,P3以及未添加热解碳的对照组P0。通过SEM、线膨胀系数测试和力学性能测试,探究不同热解碳含量对碳/碳-聚酰亚胺复合材料微观形貌结构、平均线膨胀系数以及力学性能的影响。结果表明:在20~300℃的温度区间,P0,P1,P2,P3的XY向平均线膨胀系数在(0.67~0.79)×10^(-6)℃^(-1)之间,四组XY向平均线膨胀系数基本相当。P1,P2,P3的Z向平均线膨胀系数较P0依次降低41.6%,41.8%,24.1%,热解碳显著降低了材料的Z向平均线膨胀系数。P0,P1,P2,P3的XY向压缩强度依次是243.91,244.73,216.65,210.79 MPa,Z向压缩强度依次是269.22,258.80,246.68,219.20 MPa,P1压缩强度与P0相当。P0,P1,P2,P3的Z向弯曲强度依次是92.77,77.11,80.71,86.06 MPa。不同的热解碳含量对材料的力学性能影响不同,较低的热解碳含量基本保持了材料的压缩强度,而较高的热解碳含量可基本保持材料的弯曲强度。     

Mechanical,dielectric and microwave absorption properties of carbon black (CB) incorporated SiO<Subscript>2f</Subscript>/PI composites

Structural and functional integrated absorbing materials have received extensive attention in recent years. Single-layer absorbing material composites in X and Ku bands (8.2–18 GHz) were prepared by using different proportion of carbon black (CB) incorporated quartz glass fiber reinforced polyimide resin (SiO_2f/PI). The morphology, mechanical, dielectric and microwave absorbing properties of the composites were investigated. Different contents of CB with different distributions were observed according to the fractural morphology of the composites. When the CB content is up to 8 wt%, the flexural strength of the composite reaches a maximum value of 705?±?5 MPa. The real and imaginary parts of complex permittivity both show an increasing trend with the CB content increase. Meanwhile, the real and imaginary parts decrease with the increase of frequency, exhibiting frequency-dependent dielectric response. The reflection loss of the composite was calculated based on the transmission line theory, which is in a good agreement with the experiment.     

Scavenging phenomenon and improved electrical and mechanical properties of polyaniline–divinylbenzene composite in presence of MWCNT

A semi-doped polyaniline (PANI)–dodecylbenzenesulfonic acid (DBSA) complex is added with a suspension of multiwall carbon nanotubes (MWCNT)–divinylbenzene (DVB) to prepare PANI–MWCNT based thermosetting conductive resin system. Firstly, unreinforced nanocomposites with various loading of MWCNT are prepared. Continuous improvement in the electrical conductivity is observed with increasing MWCNT loading in the composite, while improvement in the mechanical properties is observed only up to 0.2 wt% MWCNT loading. On further MWCNT loading, the decrease in mechanical properties is observed. Flexural strength increased by 18% with 0.2 wt% of MWCNT in the unreinforced nanocomposite while electrical conductivity increased continuously to 0.68 S/cm (at 0.5 wt% of MWCNT loading) from 0.25 S/cm (neat sample). DSC and TGA analysis show that MWCNT effectively contributed to enhance the scavenging effect of PANI, affecting degree of DVB polymerization at higher loading of MWCNT. Samples were characterized by FTIR analysis. DMA analysis is also performed to understand the mechanical behavior of the cured unreinforced nanocomposite under dynamic loading. SEM observation has been employed to understand the dispersion behavior of MWCNT into the matrix. PANI-wrapping behavior on MWCNT is observed from the SEM images. Wrapping of PANI on MWCNT increased doping state and surface area of PANI which subsequently contribute to the increased scavenging behavior of PANI at higher MWCNT loading. A structural thermosetting nanocomposite with electrical conductivity of 0.68 S/cm, flexural modulus of 1.87 GPa and flexural strength up to 35 MPa is prepared. In addition, PANI–DBSA/DVB matrix with MWCNT is also used to impregnate carbon fabrics to prepare highly conductive CFRPs. A CFRP with 1.67 S/cm electrical conductivity in through-thickness direction and 328 MPa flexural strength is obtained with the addition of 0.2 wt% MWCNT into the resin system.     

CIP/GF/CF/EP吸波复合材料的制备及力学性能

为制备兼具力学性能和电磁吸收性能的结构型吸波材料,采用真空辅助成型工艺设计制备一种以羰基铁粉(CIP)为吸收剂,玻璃纤维(GF)为透波层,碳纤维(CF)为反射层,环氧树脂(EP)为基体的吸波复合材料。研究了不同质量比CIP/EP对吸波复合材料力学性能和微波吸收性能的影响。通过FTIR和DSC分析可知CIP未与EP发生化学反应。SEM结果表明CIP能够在EP树脂基体中均匀分散,不趋向于纤维表面。力学测试分析结果显示:当CIP/EP质量比达到30%时,CIP/GF/CF/EP复合材料的力学性能最佳,拉伸强度为347.56MPa,拉伸模量为25.99GPa,较纯GF/CF/EP复合材料提升了4.3%和5.7%;弯曲强度为339.6MPa,弯曲模量为23.7GPa,较纯GF/CF/EP复合材料提升了18.2%和71.2%。矢量网络分析可知复合吸波板的吸波性能随CIP含量的增加而增加,且吸波损耗反射峰值朝低频段移动。     

三维针刺碳毡增强碳/氮化硼复合材料的力学和介电性能

三维针刺碳毡中碳纤维的排布方式有利于电磁波的吸收。采用碳基体和氮化硼（BN）基体与三维针刺碳毡复合, 可望获得耐高温吸波复合材料。本文中采用先驱体浸渗裂解法（PIP）制备多孔三维针刺碳/碳（C/C）复合材料, 再利用化学气相渗透法（CVI）将BN引入C/C复合材料中, 最终获得了C/C--BN复合材料。研究了CVI时间对三维针刺C/C--BN复合材料微结构、 力学性能及介电性能的影响规律。随着CVI时间的增加, C/C--BN的密度增加, 孔隙率降低, 抗弯强度提高, 介电常数增加,介电损耗降低。在CVI时间达160h后, C/C--BN密度为1.43g/cm3, 总气孔率为25%, 抗弯强度达到82MPa。      

含炔基酚醛树脂改性PSA及碳纤维布/PSA-EPAN复合材料性能

合成了乙炔基苯基偶氮酚醛树脂（EPAN）,通过溶液共混的方法用其对含硅芳炔树脂（PSA）进行改性,研究了PSA-EPAN树脂的热性能,并制备了PSA-EPAN的碳布预浸料,经热模压制备碳纤维布（T300CF）增强PSA-EPAN复合材料,对其力学性能进行了研究。结果表明：EPAN均匀分布于PSA树脂中,EPAN共混改性PSA树脂的固化温度提高,混入质量分数为7%的EPAN,N₂中固化PSA-EPAN树脂在800℃残留率超过90%,其玻璃化转变温度高于500℃,PSA-EPAN共混树脂浇铸体的弯曲性能高于PSA树脂,达40.7 MPa,提高了95.5%;PSA树脂经T300CF/PSA-EPAN复合材料力学性能显著提高,弯曲强度达到了423.5 MPa,提高了74%,层间剪切强度（ILSS）提高至29.53 MPa,增加了65%。     

Manufacture of a polymer-based carbon nanocomposite as bipolar plate of proton exchange membrane fuel cells

The aim of this paper is to prepare a polymer-based carbon nanocomposite reinforced by carbon fiber cloth (CF) to be utilized as bipolar plate of proton exchange membrane (PEM) fuel cell. For this purpose, some single, double, and triple-filler composites were manufactured by using phenolic resin as polymer (P) and graphite (G), carbon fiber (CF) and expanded graphite (EG) as fillers. The production method was compression-molding technique. The electrical conductivity, flexural strength, toughness, hardness, porosity, and hydrogen permeability tests were then measured to determine the mechanical and physical properties. A triple-filler composite containing 45 wt.% G, 10 wt.% CF, 5 wt.% EG, reinforced by a layer of CF cloth, was selected as composite bipolar plate. The electrical conductivity, thermal conductivity, and flexural strength of this composite were 74 S/cm, 9.6 W/m K, and 74 MPa, respectively, which are higher than the specified value by department of energy in USA (DOE). The composite bipolar plate used in the single fuel cell assembly showed a maximum power density 810 mW/cm². In this paper, a material selection was performed on the different materials of bipolar plates. It can be concluded that the composite bipolar plates are more suitable for high life time stationary applications.     

热塑性酚醛树脂对碳纤维环氧树脂基复合材料性能的影响

利用热重分析(TGA)、扫描电镜(SEM)和三点短梁法对添加不同含量的热塑性酚醛树脂(PF)的复合材料体系改性效果进行了研究,考察了不同含量的酚醛树脂对固化体系力学性能及热性能的影响.结果表明,随着酚醛树脂含量的增加,碳纤维环氧树脂基复合材料(CFRP)的弯曲强度和弯曲弹性模量呈递减趋势;层间剪切强度(ILSS)呈现先增加后减小的趋势,当酚醛树脂的含量为20%时,层间剪切强度达到111.31MPa,提高约7%;热稳定性较其它含量时高,复合材料体系的综合性能最好.     

高性能T800碳纤维复合材料树脂基体

在分析T800 碳纤维表面上胶剂的基础上, 系统研究了适用于制备高性能T800 碳纤维复合材料的树脂基体, 测试了树脂浇注体及其复合材料的力学性能和热机械性能, 研究了树脂基体对T800 碳纤维复合材料界面性能的影响。结果表明, T800 碳纤维表面上胶剂中酯基含量较高, 与缩水甘油酯类环氧树脂有良好的界面相容性, 经复配和优化的树脂体系其T800 碳纤维复合材料的层间剪切强度达到138 MPa , NOL 环拉伸强度达到2530MPa , 玻璃化温度( Tg ) 达到213 ℃, 具有优异的界面性能和耐热性能。      

Fabrication and mechanical properties of glass fibre–carbon fibre polypropylene functionally gradient materials

Hybrid fibre mat reinforced polypropylene (PP) composites with carbon(CF) and glass fibre (GF) were prepared and four kinds of functionally gradient materials (FGM) were fabricated by changing the spatial distribution of GF and CF. To measure the mechanical properties of FGMs and hybrid composites, flexural tests and instrumented impact tests were performed. The flexural strengths and the flexural moduli of hybrid composites increased following the rule of mixture as the relative volume content of CF increased. On the other hand, the total impact absorption energy of hybrid composites decreased with the increment of CF relative volume content. Compared with GF–CF PP isotropic hybrid composite, the composites with compositional gradient showed similar flexural strengths, but characteristic flexural moduli. Especially, sandwich-type FGMs with a CF-rich outer layer and a GF-rich inner layer exhibited higherflexural moduli than others. Total impact absorption energies of four FGMs were also similar, but the ratios of crack initiation energy,Ei, to crack propagation energy, Ep, or ductility index, were quite different.     

湿热环境下介质因素对CF/UPR复合材料的影响

研究了45℃几种介质环境中碳纤维/不饱和聚酯树脂(CF/UPR)复合材料的吸湿特性和静态力学性能的变化规律,对湿热老化前后CF/UPR复合材料进行了IR和SEM分析。结果表明,CF/UPR复合材料在5%NaCl和5%H2SO4的吸湿行为符合菲克第二定律,浸泡720h后,复合材料弯曲强度保留率均发生下降,且以碱性条件下的弯曲强度保留率下降最为严重;IR和SEM结果表明,湿热环境导致该复合材料发生基体的水解反应、界面脱粘以及基体塑化、溶胀并由此产生裂纹等缺陷。     

碳纤维增强树脂基复合材料制孔技术研究现状与展望

碳纤维增强树脂基复合材料(CFRP)具有优越的物理和力学性能,已在航空制造工业中得到大量应用。在主承力结构中,CFRP与金属材料的连接通常为机械连接。然而,CFRP的各向异性严重影响了其制孔质量。由于CFRP和金属具有截然不同的材料属性,CFRP/金属叠层结构制孔技术成为飞机装配过程中的一大难题。本文首先阐述了CFRP及其叠层结构在切削过程中的切屑形成机制、钻削力和钻削热的研究现状;其次,剖析了钻削过程中典型加工损伤,如毛刺与撕裂、分层缺陷及孔壁表面损伤的产生原因和影响因素;然后,介绍了CFRP制孔刀具材料和几何结构的优化设计研究进展,并综述了螺旋铣孔、变工艺参数钻削、"以磨代钻"和振动辅助制孔等多种CFRP及其叠层结构加工新技术及钻削过程的仿真研究。最后,借鉴钎焊工具和超声振动技术的独特优势,提出了磨粒有序排布钎焊金刚石工具的超声振动加工构想,以达到CFRP及其叠层结构的精密高效制孔加工这一目的。     

电化学氧化对高强高模碳纤维表面结构及力学性能的影响

利用循环伏安多重扫描法分析了不同电解质的氧化能力及其氧化特点,讨论了在表面氧化处理中不同电解液体系对高模高强碳纤维力学性能的影响,提出了适合高强高模碳纤维表面处理的工艺条件,并通过Raman光谱、XPS与SEM的表征,研究了电化学氧化对高强高模碳纤维表面结构及力学性能的影响。研究结果表明,与NH₄H₂PO₄溶液相比,用NH₄H₂PO₄与CH₃COONH₄复合的电解质溶液对碳纤维进行表面处理,能大幅度提高纤维表面含氧官能团,而且纤维表面sp²杂化碳原子相对含量也较多,在提高了碳纤维/环氧树脂复合材料层间剪切强度(ILSS)的同时,还较好地保持了高强高模碳纤维本体力学性能。当CH₃COONH₄与NH₄H₂PO₄的物质的量之比为2:1时,碳纤维/环氧树脂复合材料的ILSS与未处理纤维相比提高了168%,而碳纤维拉伸强度却下降很小,此复合电解质溶液是一种较为理想的对高强高模碳纤维进行表面改性的电解质体系。