SCRIMP用环氧树脂体系及其复合材料的性能研究

采用粘度、凝胶时间及力学性能测试以及示差扫描量热分析和扫描电镜研究了上纬环氧树脂2511-A体系的工艺性能,固化反应行为及其采用西曼树脂浸渍膜塑成型工艺(Seeman Composites Infusion Molding Process,SCRIMP)制成的环氧玻璃纤维复合材料的性能。结果表明:2511-A体系在25～35℃下粘度保持在600 mPa.s以下的时间长达120 min,满足SRCIMP成型工艺要求,其玻璃化转变温度为112℃。复合材料的孔隙率仅为0.19%,且具有良好的力学性能。     

Residual thermal stresses in bismaleimide/carbon fiber composite laminates

This is a study of residual thermal stresses in composite laminates, due to curing cycles. An extended formulation of Classical Lamination Theory (CLT) is adopted, which is able to take into account geometrical nonlinear effects owed to finite displacements. The approach is applied to square asymmetric laminates that have different dimensions and thicknesses. Final laminate shapes are evaluated after complete curing cycles; they can be cylindrical or saddle-like, and their equilibrium configuration stable or unstable depending on thickness vs. side length ratio. The same laminates are stacked, press-cured and the radii of curvature experimentally measured. In addition, they are modeled by means of finite element method (FEM) codes, using both linear and nonlinear techniques. Except for the thick laminates, the results obtained using nonlinear theoretical and numerical approaches show good agreement with experiment. Thermal residual strains are computed from non-mechanical strains by subtracting laminae free thermal deformations; the corresponding stresses are evaluated through layer stiffnesses. Residual stresses are evaluated both theoretically and experimentally. For thicker laminates the disagreement is mainly due to a mixed viscous phenomenon which takes place in resin interlaminar layers and matrix intralaminae. The share of relaxed stresses is evaluated and methods that include optimal cooling path techniques are suggested.     

轨道车辆用碳纤维复合材料涂装工艺

介绍了碳纤维复合材料的水性涂料选型、表面处理、施工工艺和技术要求,总结了碳纤维复合材料水性透明涂层体系和水性复合涂层体系的施工参数.通过附着力试验证明了这2个体系的漆膜在碳纤维复合材料表面的附着力满足轨道车辆的使用要求.     

Multi-walled carbon nanotube/polyimide composite film fabricated through electrophoretic deposition

Multi-walled carbon nanotube (MWCNT)/polyimide composite films were fabricated through electrophoretic deposition (EPD) of MWCNT-polyamic acid colloidal suspension which was derived from carboxylated-MWCNTs and poly(pyromellitic dianhydride-co-4,4′-oxydianiline) (PMDA-ODA). Under electric field, both negatively charged MWCNTs and PMDA-ODA colloid particles migrate onto a positively charged anode simultaneously, and are converted to a coherent MWCNT/polyimide composite film in the ensuing imidization reaction. Uniform dispersion of MWCNTs in the composite film was observed using transmission electron microscopy. The thickness of the prepared composite film can be tuned by varying processing conditions such as deposition time and anode conductivity. The electrical conductivity of the composite film increased with increasing the concentration of MWCNTs in EPD suspension. The mechanical reinforcement of polyimide using MWCNTs was evaluated by tensile testing and nanoindentation testing.     

静电纺PLA/丝素-明胶复合纤维膜的性能研究

通过静电纺丝先制备聚乳酸(PLA)纤维膜,在PLA纤维膜上分别喷射不同比例的丝素-明胶纺丝液制得PLA/丝素-明胶复合纤维膜,对复合纤维膜的溶解性能、尺寸稳定性、力学性能及生物性能进行表征。结果表明:与丝素-明胶纤维膜相比,PLA/丝素-明胶复合纤维膜的溶失率明显下降,尺寸稳定性及柔软性得到改善,且经甲醇处理后,复合纤维膜的力学性能提高。将制备的复合纤维膜进行小鼠胚胎细胞(3T3)培养实验,3T3在PLA/丝素-明胶复合纤维膜上能更好地粘附、伸展和繁殖。     

Reduction of microvoids in composite laminates fabricated by bladder assisted composite manufacturing (BACM)

Bladder Assisted Composite Manufacturing (BACM) is a recently developed out‐of‐autoclave process designed to fabricate geometrically complex, hollow composite parts. This paper assesses the ability of three new BACM process variations to fabricate parts with high fiber and low void contents. This was achieved by fabricating 4‐ply cylinders from a carbon/epoxy prepreg at cure pressures of 207 and 483 kPa. The fiber/void content, mechanical properties, and energy consumed during the curing of the cylinders are investigated and compared to the original BACM process. The fiber content of the cylinders were observed to be dependent on both bladder pressure and BACM variation used, reaching a maximum fiber content of 66% which is 5% greater than that obtained by the original BACM process. The elastic moduli and failure strength results for the cylinders were found to increase with fiber content and showed no preference to any of the studied BACM process variations. In addition, the void content of the cylinders were reduced by 94% with the utilization of a porous bleeder fabric when compared to the original BACM process. POLYM. COMPOS., 37:561–572, 2016. © 2014 Society of Plastics Engineers     

近期碳纤维及其复合材料的新发展

综述了近一年来东丽通过2013年9月收购世界最大的大丝束聚丙烯腈基碳纤维(PAN-CF)企业ZOLTEK后,其销售额比去年同期提高40%,同时不断提高小丝束PAN-CF产能,开发出T1100超高性能新品种,并大力发展下游复合材料产业链,使之一举成为世界顶级碳纤维企业。其他两家日本PAN-CF厂家及更多的日本企业纷纷发展碳纤维复合材料(CFRP)产业,特别是面向航空工业和汽车产业的高档CFRP制品,以确保未来的领先地位和日本经济的可持续发展。并介绍了碳纤维增强热固性树脂和热塑性树脂的新发展和新技术,特别是美国火箭发动机壳体材料的沿革和复合材料的脱热压罐技术的发展趋势。     

碳纤维及预浸料工程设计探讨

本文对碳纤维及其预浸料装置生产工艺特点及主要生产安全环保问题进行了适当的分析,指出了工程设计中应注意的工艺技术要求,关键的技术参数和安全保证措施．     

A radial infusion model for transverse permeability measurements of fiber reinforcement in composite materials

The goal of this article was to develop a method for simultaneously determining the principal values of an unsaturated permeability tensor for fibrous reinforcements which accounts for finite dimension of the inlet gate, when its diameter is comparable or larger than thickness of a fabric preform. An analytic solution for the direct problem of liquid spreading in a transversely orthotropic fabric preform is derived and analyzed. This solution is compared with a point source approximate solution used by other authors. Algorithms for evaluating the principal components of transverse and equivalent in-plane permeability are proposed. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Resin flow monitoring inside composite laminate during resin film infusion process

In this article, a novel method of measuring resin flow front under vacuum condition is presented. The in situ monitoring system with metal hollow probe based on gas flow balance can be used in resin film infusion (RFI) process, where resin film is used and transverse flow is dominated along thickness direction of fiber preform. The diameter of the probe was chosen to increase the measuring accuracy, and the reliability of the method was evaluated by comparison of visualization experiment. Experimental results demonstrate that the method is suitable for monitoring resin flow in RFI process with and without autoclave, and can obtain the information about resin filling time, nonuniform flow front, and the permeability of fiber preform. Furthermore, by means of the established monitoring system, the influences of pressure and lay‐up sequence of carbon fiber fabric on epoxy resin flow during RFI process were investigated. In addition, resin flow pattern with changing viscosity of epoxy resin was studied. POLYM. COMPOS., 35:681–690, 2014. © 2013 Society of Plastics Engineers     

Joining of carbon fiber reinforced polymer laminates by a novel partial cross‐linking process

Direct joining of partially cross‐linked and freshly infiltrated carbon fiber reinforced epoxy resin plates made from HTA/RTM6 is investigated as function of the partial curing degree. Partial cross‐linking maintains a certain chemical reactivity of the thermosetting resin which can be used for bonding to a second, freshly infiltrated resin part. A final curing cycle guarantees complete cross‐linking of the joined component. The bonding behavior and the interface morphology of the joined plates are analyzed by mechanical testing, acoustic emission analysis and microscopy. A significant dependence of the bonding and interfacial properties on the partial curing degree is found. Very low and very high partial curing degrees (below 70% and above 80%) result in low fracture toughness and discontinuous crack propagation. Intermediate curing degrees between 70% and 80% mainly show high fracture toughness, stable crack propagation and a ripple like interface morphology. The latter is created by the surface morphology of the partially cross‐linked plate with the typical peel‐ply imprint and results in a high contact surface and mechanical interlocking. The combination of chemical reactivity and high contact surface seems to be advantageous for the enhanced fracture toughness and the improved failure mode of samples with intermediate partial curing degree. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42159.     

Properties of silicon-containing carbon fiber materials prepared using cellulose

Silicon-containing carbon fiber sorbents, which exhibited sufficiently high sorption activity and increased stability to the action of oxygen at high temperatures, as compared with that of an analogous material based on individual cellulose, were prepared by the carbonization and the subsequent activation of cellulose compositions with polycarbosilane.     

Curing processes simulation of complex shape carbon fiber reinforced composite components produced by vacuum infusion

Thermal processes of carbon fiber‐reinforced composite parts curing cycle were studied experimentally and by mathematical simulation. Flat panel, T‐stringer, and five‐stringer detail based on tetrafunctional MY721 epoxy resin were investigated. Application of standard curing cycle (heating followed by isothermal exposure at 180°C) leads to the overheating of 28°C in flat panel and of 30°C in T‐stringer of 24 mm thickness. The model considers the vacuum bag with auxiliary materials as separate layers. This approach allows to simulate the shifting of thermal field to the vacuum bag side. Simulation results show good agreement with the experimentally observed temperature fields. The model helps to optimize the curing cycle to reduce the local overheating. The same temperature regime could be used for all three geometries. Therefore, the optimization can be carried out only for the simple‐shape parts to save the calculation time and simplify experiments at the stage of model testing. POLYM. COMPOS., 37:2252–2259, 2016. © 2015 Society of Plastics Engineers     

Viscoelastic effects related to residual thermal stresses in bismaleimide/carbon fiber composite laminates

This paper studies the effects of the residual stresses which originate in the laminates made of composite materials owing to the curing process, and on stresses affected by time and temperature. In order to sustain high operating temperatures, the polymer composites' laminates are made of high performance matrices that usually require processing cycles at high temperatures. The strong thermal variation due to the subsequent cooling process induces residual stresses, owing to the thermoelastic orthotropy of the material. For non-symmetrical stacking sequences, these stresses notably modify the shape of the laminate and reduce both its static strength and buckling load, as a consequence of the latent content of elastic energy stored by the pre-loading. The polymeric composites show a viscoelastic behavior, which implies a constitutive law dependent on both time and temperature. For this reason, the analysis of the phenomenon should account for the creep and the relaxation mechanisms. The configuration of asymmetric laminate is evaluated by both analytical and numerical finite element (FEM) methods. The actual shape of laminates of different geometries is also experimentally determined. On the basis of the analysis of the shape of laminates measured after different thermal cycles, the evolution of residual stresses with time and temperature is analyzed.     

Toughening of carbon fiber/epoxy composite by inserting polysulfone film to form morphology spectrum

Fracture toughness of the polysulfone(PSf) film modified epoxy composite having a morphology spectrum was investigated. The epoxy resin was based on diglycidyl ether of bisphenol-A (DGEBA type) and diaminodiphenylsulfone (DDS). 1K carbon fabric was used as reinforceing material. The morphology spectrum which has gradual change of the morphological feature resulting from the concentration gradient of PSf in the composite can be obtained by inserting the PSf film in carbon fiber reinforced epoxy prepreg before cure. The relative rate of the dissolution and diffusion of the PSf in the epoxy determine the concentration gradient of the PSf. As the concentration of the PSf increases, the morphology changes from sea-island to nodular structure. The fracture toughness of the composite with 20 wt% PSf film was 2.7 times higher than that of the unmodified composite. This result was ascribed to the plastic deformation of the continuous PSf rich phase in the semi-IPN having morphology spectrum.     

日本碳纤维复合材料在汽车领域应用的新进展

介绍了日本碳纤维生产企业近几年的扩产计划与战略布局,以及日本碳纤维生产企业与合作科研单位在碳纤维复合材料（CFRP）的研发进展情况.指出占据世界碳纤维市场70％份额的日本碳纤维生产商一贯高度重视CFRP的下游应用,尤其率先在汽车领域应用研发的大量投入,成为全球碳纤维行业发展的领衔者,亟须我国碳纤维产业的顶层设计和从业者们的高度重视和借鉴.     

静电纺PAA/PAN复合碳纤维膜的制备及其性能研究

采用不同结构的二酐、二胺单体设计制备了含对称结构单元和含不对称结构单元的聚酰胺酸(PAA),通过静电纺丝分别制备PAA、聚丙烯腈(PAN)、PAA/PAN复合物的纳米纤维膜(ENFs),将ENFs在空气中热稳定化后,在1 000℃的氮气气氛中碳化,制成不同前驱体的静电纺碳纳米纤维膜(ECNFs);研究PAA结构单元的对称性及PAA与PAN的复合对ENFs的热稳定化、碳化行为以及ECNFs导电性能的影响。结果表明:含不对称结构单元PAA的ENFs碳化收率较高,制备的ECNFs石墨微晶尺寸较大;将含不对称结构单元PAA与PAN复合时ENFs在1 000℃碳化时质量保持率达45%,且得到的ECNFs的石墨微晶尺寸与平均堆叠层数分别达1.69 nm和4.71,优于其他前驱体的ECNFs的微晶结构;PAA中的不对称结构单元及其与PAN的复合都有助于提升ECNFs的电导率,复合物的ECNFs的电导率最高可达9.08 S/cm;含不对称结构单元PAA与PAN形成了良好的协同碳化效应,可促使ECNFs的石墨晶粒的堆积和生长,提高ECNFs的导电性能。     

钓鱼竿用大丝束碳纤维预浸料的研制

本文简要介绍了钓鱼竿用大丝束(60K)碳纤维预浸料熔胶膜法浸渍工艺，并着重就影响预浸料质量的几个主要因素进行了讨论。     

关于碳纤维及其复合材料测试方法的标准化

论述了国内外碳纤维及其织物、预浸料、复合材料的测试方法及标准化,供国内有关测试单位及专业技术人员参考。     

Impact-Induced delamination in [05, 905, 05] carbon fiber/polyetheretherketone composite laminates

This paper reports both experimental and numerical investigations on delamination mechanisms in [0₅, 90₅, 0₅] carbon fiber(CF)/poly(etheretherketone) (PEEK) laminate subjected to low-velocity impact. It was found that the CF/PEEK composite exhibits the same damage mechanisms as epoxy-based composites, but superior delamination resistance. For the crossply laminate, the impact delamination results from a Mode II interlaminar fracture process, and a close association exists between the interlaminar shear stress field and the delamination growth. The prediction of impact-induced delamination sizes is discussed.