碳纤维湿法缠绕用环氧树脂基体研究

以TDE-85树脂和AFG-90树脂为主体树脂,混合芳香胺为固化剂,研究了一种适合于碳纤维复合材料湿法缠绕成型的树脂配方。结果表明,该树脂的黏度低(＜550 mPa·s)、适用期长,其浇铸体具有优异的力学性能,其拉伸强度为107 MPa,拉伸模量为4．09 GPa,弯曲强度为161 MPa,弯曲模量为3．88 GPa,断裂伸长率超过6%。用其制备的T-700碳纤维缠绕复合材料界面粘接好,NOL环层间剪切强度达到66．8 MPa,拉伸强度达到2．44 GPa。     

聚吡咯层对碳纤维/环氧树脂复合材料界面粘结性能的影响

以三氯化铁为氧化剂,采用吡咯液相沉积聚合方法制备聚吡咯-碳纤维(PPy-CF),然后与环氧树脂(EP)复合,制得PPy-CF/EP复合材料,并对其进行拉伸性能测试,研究了聚合温度对PPy-CF/EP复合材料界面剪切强度(IFSS)的影响。结果表明:在CF表面吡咯沉积聚合最佳工艺条件为聚合温度70℃,时间30min,经过吡咯沉积聚合改性后,得到的PPy-CF/EP复合材料的IFSS有所提高;最佳条件下制得的PPy-CF/EP复合材料的IFSS是CF/EP复合材料的1.24倍;在PPy-CF中,PPy与CF之间无化学键作用,PPy-CF/EP复合材料的IFSS与PPy-CF表面含氧基团和粗糙度有关;吡咯化学沉积聚合改性是一种提高纤维与树脂界面粘结性能的有效方法。     

Preparation of transparent and conducting carbon nanotube/N-hydroxymethyl acrylamide composite thin films by in situ polymerization

The preparation of optically transparent and electrically conductive composite thin films composed of multi-walled carbon nanotube (MWCNT) and poly N-hydroxymethyl acrylamide were fabricated by a simple in situ polymerization technique. The film displays conductivities up to 10³ S/m depending on the MWCNT loading and a sheet resistance as low as 53 Ω/□ for an optical transparency greater than 95% at 550 nm. The dispersability characteristics of the suspension were determined by measuring specific surface charge, rheological behavior and UV–vis spectra.     

碳纤维增强树脂基复合材料的应用研究

碳纤维增强树脂基复合材料以其优异的综合性能成为当今世界材料学科研究的重点。本文介绍了的碳纤维增强复合材料的性能，简述了增强机理、成型工艺及其应用领域和发展趋势。     

Nylon 610 and carbon nanotube composite by in situ interfacial polymerization

Poly(hexamethylenesebacamide) (nylon 610) nanocomposites containing well dispersed multi-walled carbon nanotubes (MWNTs) were successfully produced via the in situ interfacial polymerization of two liquid phases, one containing hexamethylenediamine in the presence of MWNTs and the other containing sebacoyl chloride. The processing consisted of dispersing acid-treated MWNTs in an aqueous phase containing a Triton X-100 surfactant. Scanning and transmittance electron microscopies showed that the individual MWNTs were uniformly dispersed in the nylon 610 matrix. Tensile tests of the composite sheet showed a 170% increase in the Young's modulus with slight increases in the tensile strength and the elongation at break (about 40 and 25%, respectively). This suggests an interaction between the acid-treated MWNTs and nylon 610. The thermal stability of the composite was also enhanced by the incorporation of MWNT into nylon 610 matrix.     

原位聚合法制备环氧树脂/石墨复合材料的性能研究

采用原位聚合法制备了环氧树脂/石墨复合材料,并对其进行热重(TG)、扫描电镜(SEM)和力学性能分析。结果表明,环氧树脂/石墨复合材料的邵氏硬度和抗弯强度随石墨含量而变化,当其含量为17.44%(质量分数)时,两者出现最大值,抗弯强度达到22.4 MPa,邵氏硬度达到5.21 HD;石墨的加入也使复合材料的电性能和热性能得到提高,其耐热温度可达350℃。     

环氧树脂/短切碳纤维复合材料性能研究

制备出了短切碳纤维增强TDE-85环氧树脂复合材料,研究了碳纤维的含量对复合材料力学性能和耐热性能的影响。结果表明,碳纤维的加入有利于复合材料力学性能和耐热性能的提高,并在碳纤维含量为0.25%时,复合材料的拉伸强度、冲击韧性、弯曲强度和弯曲模量达到最大,分别提高了29.33%、25.31%、30.28%和68.93%。此外,对复合材料的弯曲断裂面进行了微观形貌分析,结果表明一定量的碳纤维可以较好地分散在树脂基体中,同时,碳纤维原丝和树脂基体的界面结合比较弱,主要依赖于两相之间的物理嵌合。     

Multiwalled carbon nanotube/polyacrylonitrile composite fibers prepared by in situ polymerization

Multi‐walled carbon nanotubes (CNTs) were mixed with polyacrylonitrile (PAN) by in situ polymerization or by mechanically mixing. The mixtures were then wet‐spun into fibers, respectively. The effects of mixing method on the interfacial bonding between the components in the fibers and the properties of the fiber were investigated by Raman spectroscopy, TEM, SEM, and tensile strength testing. By in situ polymerization mixing, a thin layer of PAN molecules is observed to cover the surface of the CNT, which increases the diameter of CNT evidently. Results of Raman spectroscopy indicate that the layer of PAN molecules are strongly attached onto the surface of CNT through grafting polymerization, leading to strong chemical bonding between CNTs and PAN matrix in the obtained fibers. In contrast, no obvious chemical interactions are observed between them in the fibers prepared by mechanically mixing. In both cases, the CNTs have significantly strengthened the PAN fibers. However, the fibers prepared from in situ polymerization mixing are much stronger because of the interfacial bonding effect between the PAN molecules and CNTs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

液体成型用环氧树脂体系与碳纤维表面浸润性能研究

采用1,4-丁二醇二缩水甘油醚(BDDGE)、聚乙二醇二缩水甘油醚(PEGDGE)、双酚A聚氧乙烯醚06(BPE-06)3种活性环氧树脂稀释剂,分别制备了低黏度适合复合材料液体成型工艺(LCM)的环氧树脂体系,研究了体系与国产碳纤维(HF10)的表面浸润性。首先,研究了稀释剂结构、用量对环氧树脂体系与碳纤维湿润性的影响;其次,研究了稀释剂/树脂/固化剂体系的湿润温度、反应程度对树脂与碳纤维表面的浸润性影响。采用DCAT21表面/界面张力仪分析了树脂与碳纤维界面的前进接触角;采用Young-Dupre法,计算了树脂与碳纤维的热力学粘附功。结果表明,采用稀释剂降低黏度,可以有效改善树脂体系与碳纤维的浸润性;相同黏度时,不同结构稀释剂提高浸润性效果顺序为:PEGDGEBPE-06BDDGE;升高温度可以提高环氧树脂与碳纤维的浸润性;随着反应程度的提高,树脂体系与碳纤维的湿润性变好。     

Comparison of polyimide/multiwalled carbon nanotube (MWNT) nanocomposites by in situ polymerization and blending

In this research, multiwalled carbon nanotube (MWNT) was oxidized and then modified to form carboxylic groups (? COOH) on the surface and the end of the tube. After that, the MWNT was added to polyimide matrix to enhance its mechanical and electrical properties by in situ polymerization and blending. The PI/MWNT composites were obtained by spin coating and multistep thermal curing process. The comparison of in situ polymerization and blending as well as the effect of unmodified and modified MWNT were discussed in this study. The results indicate that in situ polymerization is able to make a perfect dispersion by adding modified MWNT into polyimide matrix. Thermal and mechanical properties of the composites can be improved by hydrogen bonding interaction between the modified MWNT and polyimide matrix. Electrical resistance of the composites can be decreased to meet the criterion of electrostatic charge (ESC) mitigation as the surface resistance is reduced into the range of 10⁶–10¹⁰ Ω/cm² by adding modified MWNT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of stress transfer between fiber and matrix on toughness of polymer composite

Thanks to their lightweight properties, formability and low cost, polymers have become an essential material for manufactured products. To improve the mechanical properties, almost all polymers are blended with some kind of fiber made from glass, carbon, organic or natural material. The importance of interfacial strength between matrix and fiber is a well known requirement for effective mechanical properties and some experimental results indicate that low interfacial strength helps increase the toughness of composites. In this paper, models of composite reinforced by fiber aligned with maximum principal stress under uni‐tensile loading are simulated. Based on the simulation result, we discuss the effect of interfacial strength, aspect ratio of fiber and friction force between matrix and fiber on stable deformation and provide the guidelines for establishing composites with high modulus and toughness. POLYM. COMPOS. 2011. © 2011 Society of Plastics Engineers     

碳纤维增强环氧树脂基复合材料的性能研究

研究了WBS-3环氧树脂固化体系的反应特性,分析了该固化体系浇铸体的性能;并以碳纤维(T-700S)为增强材料,采用手糊成型螺栓加压工艺制备了WBS-3/T-700S复合材料,研究了复合材料的常温力学性能、高温力学性能、水煮后力学性能和动态力学性能,并对弯曲断面进行分析。研究结果表明,WBS-3树脂基体黏度低、适用期长且韧性好,适合于手糊成型、缠绕成型等低成本制造工艺;由此制得的WBS-3/T-700S复合材料具有优良的力学性能和耐高温性能,其弯曲强度为1434MPa,拉伸强度为1972MPa,剪切强度为76.1MPa,玻璃化温度(Tg)超过210℃;该WBS-3/T-700S复合材料具有很好的界面粘接性(树脂对纤维的浸润性良好)、较低的空隙率且纤维分布均匀。     

The pull-out and failure of a fiber bundle in a carbon fiber reinforced carbon matrix composite

The interfacial failure is examined for a unidirectionally reinforced carbon fiber/carbon matrix composite. A novel tensile test is conducted which realizes the processes of interfacial debonding and subsequent pull-out of a fiber bundle from the surrounding composite medium. The critical stress at the onset of delamination cracking is related to the fracture energy (the critical energy release rate for mode II cracking). A force-balance equation of a fiber bundle, which is quasi-statically pulled-out of the composite socket, is formulated in terms of the inter- and intra-laminar shear strengths of the composite. This equation is successfully used to estimate the delamination crack length along the debonded fiber bundle, as a function of the stress applied to the bundle.     

Flexible polymer‐multiwall carbon nanotubes composite developed by in situ polymerization technique

Mechanically robust and flexible polymer‐multiwall carbon nanotubes (MWCNT) composites are developed by in situ polymerization technique, where MWCNT are embedded in nontoxic, bio‐compatible acryl amide‐based polymer matrix. The addition of glycerol in the composite imparts required flexibility and a further addition of poly (3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) shows significant improvements in tensile modulus, strength, and toughness compared to the polymer matrix. The composite is characterized by Scanning electron microscopy, Raman spectroscopy Attenuated total reflectance Fourier Transform infrared spectroscopy. At optimized conditions; the composite forms a heterojunction diode with n‐Silicon having an electronic rectification ratio of 2.11 at ±1 V and a further addition of conducting polymer PEDOT: PSS in the composite enhances the electronic current rectification to 13.63 at ±1 V, with the turn on voltage of the device at 0.35 V. POLYM. COMPOS., 37:2860–2870, 2016. © 2015 Society of Plastics Engineers     

Effect of external heat flux on the thermal diffusivity and ablation performance of carbon fiber reinforced novolac resin composite

Ablation is an effective and reliable method largely used in aerospace structures and other high temperature conditions to protect the payload from the damaging effects of external high heat flux. In an ablation process, the high heat fluxes are dissipated by the material through a series of endothermic processes. This finally leads to the loss and the consumption of the material itself. The ablative material keeps the surface temperature within a certain range, and as a consequence an increase of the heat flux will not cause a consistent temperature rise, but will bring about an increase of the surface recession rate. The objective of this work is to give information on the effect of the external heat flux to evaluate effective thermal diffusivity behavior and ablation performance of carbon fiber reinforced composite based on novolac resin. Here, we calculate the effective thermal diffusivity of this composite at different heat flux conditions using inverse solution technique of conservation equations of mass and energy. The ablation performance evaluation is based on experimental transient ablation rate measurement in oxyacetylene flame test. The results of this work explained the ablation process and thermal diffusivity behavior of this composite as a high performance heat shield at high external heat fluxes.     

High-temperature vapor deposition polymerization polyimide coating for elimination of surface nano-flaws in high-strength carbon fiber

The effect of polyimide coatings on the filament tensile strength of high-strength polyacrylonitrile-based carbon fiber was studied by using dip and high-temperature vapor deposition polymerization (VDP) coating processes. Unlike a VDP on a cold substrate, high-temperature VDP has the potential to directly synthesize and isotropically deposit a polyimide, from diamine and dihydride monomers without any by-products, on a substrate heated up to 200 °C. The average filament tensile strength of the flaw-sensitive carbon fiber improved with all the polyimide coatings used. Nevertheless, for the same monomers, the high-temperature VDP coating process was advantageous for high-efficiency surface flaw healing compared to the dip-coating process, resulting in a 25% increase in the average tensile strength of the carbon fiber. These results were evident not only for the carbon fibers without artificial nano-notches but also for those with artificial notches less than 30 nm in depth. Thus, we clearly showed the potential for the VDP polyimide coating to heal surface nano-flaws of the carbon fiber. The different infiltrations of the coating into nano-notches and its effect on the filament tensile properties were characterized, as well as discussing the impact of the VDP coating with an interlayer between the coating and the fiber.     

Fabrication of polystyrene/multiwalled carbon nanotube composite films synthesized by in situ microemulsion polymerization

A microemulsion polymerization method was used to achieve better compatibility between polystyrene (PS)/multiwalled carbon nanotubes (MWCNTs) nanocomposites and the host PS matrix to form films with excellent electrical and thermal properties. The films were prepared by embedding the PS/MWCNTs nanocomposite into the PS matrix. The MWCNTs were functionalized with PS nanoparticles to avoid the phase separation problem between the filler and host matrix and to enhance the good dispersibility of MWCNTs in the PS host matrix. The confirmation of the synthesis was analyzed by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and Raman spectroscopy. The variation effect of the PS‐linking density on the MWCNT was revealed by scanning electron microscopy and transmission electron microscopy. An enhancement of the thermal and mechanical properties was revealed by thermal gravimetric analysis, differential scanning colorimetric analysis, and dynamic mechanical analysis. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Thermal degradation of high‐temperature fluorinated polyimide and its carbon fiber composite

High‐temperature polymers are being used for a broad range of applications, such as composite matrices for structural applications (e.g., high speed aircraft). Polyimides are a special class of polymers that meet the thermal and oxidative stability requirements for high temperature composite aerospace applications. A weight loss study was performed on a fluorinated polyimide resin and its carbon fiber composite in an effort to determine its thermal stability and degradation mechanisms. Experiments were conducted using a preheated oven and thermogravimetric analysis to obtain the weight loss. Regardless of the method used, the resin and composite exhibited excellent thermal stability (less than 1% weight loss) below 430°C, regardless of 2–20 min of exposure. After 20 min of exposure at 510°C, the composite remained relatively stable with only 5.3% weight loss using the oven technique, whereas the neat polyimide sustained 12.6%. When degradation occurred, it was found to be the result of thermolysis and oxidation (to a lesser extent). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

改性双马树脂/碳纤维复合材料体系耐湿热性能研究

对5428/T700复合材料的吸湿率、不同吸湿条件下的玻璃化转变温度及高温湿态力学性能进行了研究。结果表明,5428/T700体系具有较低的吸湿率,经70℃去离子水水煮72 h,吸湿率为0.5%,饱和吸湿率(水煮360 h)为0.8%。而且随着复合材料吸湿量的增加,其Tg下降缓慢;5428/T700复合材料在干态170℃下的弯曲性能和层间剪切性能保持率在70%以上,在湿态150℃下的弯曲性能和层间剪切性能保持率在50%以上;5428/T700复合材料在湿态150℃下的开孔压缩强度保持率在80%以上。