改性碳纤维/有机硅复合材料的制备及力学性能研究

碳纤维是制备高性能树脂基复合材料最有前途的增强材料之一。为提高碳纤维与复合材料的界面性能,使用乙烯基三叔丁基过氧硅烷(VTPS)对碳纤维表面进行改性,并通过扫描电子显微镜和傅里叶变换红外光谱仪研究了改性方法对碳纤维表面结构的影响,考察了碳纤维添加量对复合材料力学性能的影响。结果表明,改性后的碳纤维表面引入了乙烯基、羟基和羧基等活性基团,同时保持了纤维的形貌。引入的乙烯基能够参与交联反应,促进硫化过程。此外,改性后的碳纤维能有效增强复合材料的力学性能,随着碳纤维添加量的提高,复合材料的力学性能得到显著增强。     

纳米SiO_2-NaOH-有机硅烷偶联剂表面改性对苎麻纤维/乙烯基酯树脂复合材料性能的影响

为改善苎麻纤维/乙烯基酯树脂复合材料的力学性能和吸湿性能,采用纳米SiO_2联合NaOH和有机硅烷偶联剂KH570对苎麻纤维进行改性,考察了该表面改性方法对苎麻纤维化学结构、表面形貌、结晶度及对苎麻纤维/乙烯基酯树脂复合材料的力学性能和吸水性的影响。结果表明,苎麻纤维表面的胶质被NaOH溶解,纤维吸水性变强,变得疏松,与树脂基体的黏结性增强,纤维结晶度随着碱浓度的增加先升高后降低;有机硅烷偶联剂KH570与苎麻纤维发生偶联作用,静态水接触角增大,疏水性增强,使苎麻纤维/乙烯基酯树脂复合材料界面性能提高;在有机硅烷偶联剂KH570作用下,SiO_2以纳米级尺寸与苎麻纤维表面羟基产生共价键,从而提高了苎麻纤维/乙烯基酯树脂复合材料的力学强度;实验表明,该方法改性后的苎麻纤维/乙烯基酯树脂复合材料吸水率大大降低。     

纤维热氧-接枝处理与基体改性对CF/VE复合材料力学性能的影响

针对碳纤维增强乙烯基酯树脂(CF/VE)复合材料界面性能薄弱的问题,通过热氧-接枝的方法对碳纤维表面进行改性,通过添加偶联剂改性树脂,并采用真空辅助成型工艺制备了CF/VE复合材料。通过纤维扫描电镜(SEM)表征和CF/VE复合材料力学性能测试、动态力学测试、界面粘结参数计算以及界面的微观表征验证改性方法的效果。SEM测试表明改性后纤维比表面积和粗糙度提高;TGA测试表明碳纤维氧化温度大于210℃,且氧化温度在600℃时,CF/VE复合材料综合性能最佳;CF/VE复合材料界面性能随隅联剂质量浓度的增大先提高后降低,且在其质量浓度为1%时,层间剪切强度最大,相对于未改性CF/VE复合材料的提高了74.3%;动态力学性能测试(DMA)表明改性CF/VE复合材料的玻璃化转变温度Tg较未改性的提高了约10℃;界面粘结参数A和α的定量计算表明改性CF/VE复合材料界面性能得到较大改善。     

臭氧处理对石墨纤维复合材料性能的影响

为改善石墨纤维和氰酸酯树脂间的界面性能,利用臭氧处理技术对石墨纤维进行表面处理,并采用AFM、XPS和IR对处理前后的石墨纤维表面形貌和组成进行了分析,研究了臭氧处理对石墨纤维/氰酸酯复合材料层间剪切强度和弯曲强度的影响.实验结果表明:臭氧处理提高了碳纤维表面活性,从而改善了石墨纤维/氰酸酯复合材料的界面粘结性能,进而改善了复合材料的界面和力学性能.     

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。     

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。      

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...     

国产碳纤维与东丽碳纤维与PP复合材料性能的对比研究

分别采用国产永煤及日本东丽未处理过的碳纤维及经浓硝酸处理的碳纤维,制备了碳纤维增强聚丙烯(PP)复合材料。通过测量复合材料的力学性能表明加入少量未处理的国产永煤碳纤维,CF/PP复合材料的力学性能有了很大的提高,反之未处理的东丽碳纤维增强效果不明显。通过SEM分析了表面处理前后碳纤维复合材料界面的变化,结果表明对日本东丽碳纤维进行硝酸表面处理后可显著改善基体与碳纤维的界面粘结性能,进而提高CF/PP复合材料的力学性能。     

等离子体处理碳纤维/树脂复合材料

为了提高碳纤维/树脂复合材料的表面浸润性,采用等离子体直接对复合材料进行表面处理,通过接触角测试、拉伸试验、金相显微分析和红外光谱分析,探究了等离子体处理碳纤维/树脂复合材料的最佳处理工艺、处理前后碳纤维/树脂复合材料的力学性能和表面官能团的变化。结果显示:电流、气压和处理时间均对碳纤维/树脂复合材料表面浸润性有明显影响,当电流为1.0A、气压为1.0Pa、处理时间为10min时,表面浸润性最佳;处理后碳纤维/树脂复合材料的拉伸强度没有减小,反而提高了8%。红外光谱分析显示处理后碳纤维/树脂复合材料表面酯基链发生断裂,酯基数量降低,相应形成更多的酮基、羧基和醇羟基,表面极性增强,浸润性显著提高。研究解决了碳纤维/树脂复合材料表面呈惰性的问题,为其表面功能涂层制备奠定了基础。     

乙烯基酯复合材料/橡胶界面性能研究

通过对橡胶表面进行处理并涂刷柔性过渡层,研究橡胶与乙烯基树脂复合材料的界面粘接性能。结果表明,橡胶表面经过化学处理后,出现大量细小微裂纹,使得橡胶与乙烯基酯复合材料的界面粘接强度得到大幅度提高;在经过化学处理后的橡胶表面涂刷柔性能渡层,二者界面剥离强度提高到2.90 k N/m,粘合强度达到2.30 MPa。     

Properties of thermo-chemically surface treated carbon fibers and of their epoxy and vinyl ester composites

Carbon fibers were surface treated by a continuous gas phase thermo-chemical treatment. The surface and the mechanical properties of the fibers were investigated before and after treatment and compared to the properties obtained with a conventional industrial electro-chemical surface treatment. The increase of the oxygen atomic content was much sharper, the surface chemistry was better controlled, and the tensile strength of the fibers increased slightly with the thermo-chemical surface treatment. The thermo-chemical surface treatment created a topography which amplitudes were under 10 nm, thus creating some mechanical interlocking with the matrix. The electro-chemical surface treatment did not generate such a topography. The improvement of interfacial adhesion with a vinyl ester matrix was limited, revealing that oxidation of the carbon fiber surface alone cannot tremendously improve the mechanical properties of carbon fiber–vinyl ester composites.     

Improving the interfacial property of carbon fiber/vinyl ester resin composite by grafting modification of sizing agent on carbon fiber surface

The poor interfacial adhesion between carbon fibers (CFs) and vinyl ester resin (VE) has seriously hampered the application of CFs/VE composites. In this work, the interfacial adhesion was efficiently enhanced by grafting acrylamide with epoxy sizing agent on CFs surface. The grafting reaction was feasible according to the thermodynamic calculation. The optimal grafting condition was 80 °C for 10 min based on the kinetic investigation by differential scanning calorimeter. Surface morphology and surface composition of modified carbon fibers (MCFs) were characterized, which indicated that acrylamide was grafted successfully on CFs surface and the surface roughness was increased slightly. After grafting, the interface shear strength of MCFs/VE composites was significantly improved by 86.96% and the interlaminar shear strength was enhanced by 55.61% due to the covalent bonds in interphase and the toughening effect of sizing gent. Moreover, the static and dynamic mechanical properties of composites with different interfacial adhesion were measured, which further confirmed the effect of the grafting modification.     

Composites from Natural Fibers and Soy Oil Resins

The goal of this project is to develop new composites using fibers and resins from renewable resources. The ACRES (Affordable Composites from Renewable Sources) group at the University of Delaware has developed new chemistries to synthesize rigid polymers from plant oils. The resins produced contain at least 50% plant triglycerides and have mechanical properties comparable to commercially available synthetic resins such as vinyl esters, polyesters and epoxies. This project explores the development of all-natural composites by using natural fibers such as hemp and flax as reinforcements in the ACRES resins. Replacing synthetic fibers with natural fibers has both environmental and economic advantages. Unlike carbon and glass fibers, natural fibers are abundantly available from renewable resources. In terms of cost, natural fibers are cheaper than the synthetic alternatives. The natural fibers and plant-based resins have been shown to combine to produce a low cost composite with good mechanical properties. Tensile strength in the 30 MPa range has been obtained for a composite containing about 30 wt% Durafibre Grade 2 flax. The tensile modulus was found to be 4.7 GPa for a 40 wt% flax composite. Similar numbers where obtained for the hemp composites obtained from Hemcore Inc. Composites from renewable resources offer significant potential for new high volume, low cost applications.     

碳纤维改性对不饱和聚酯自修复复合材料性能的影响

采用H_2O_2和浓HNO_3对碳纤维(CF)表面分别进行氧化处理,得到氧化碳纤维(OCF1和OCF2),采用硅烷偶联剂γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH-570)对OCF1进行接枝处理,得到接枝改性碳纤维(KCF),将改性前后CF应用于不饱和聚酯(UP)自修复复合材料中,分析比较了不同改性剂及改性方法对碳纤维/不饱和聚酯(CF/UP)自修复复合材料性能的影响。利用FTIR、XPS、SEM表征CF与CF/UP自修复复合材料的化学结构与形貌,通过TGA、万能拉力试验机、悬臂梁冲击仪、邵氏硬度计等对复合材料的热稳定性、力学性能及自修复效率进行测试。结果表明:氧化、接枝反应均可增加CF表面的粗糙度和活性官能团含量,从而改善CF与UP基体的界面相容性。其中OCF1/UP自修复复合材料的综合力学性能比OCF2/UP自修复复合材料好,KCF/UP自修复复合材料的力学性能在三者之中最佳,其自修复效率最高,可达67.03%。     

Influence of fibre surface oxidation–reduction followed by silsesquioxane coating treatment on interfacial mechanical properties of carbon fibre/polyarylacetylene composites

Carbon fibre was treated with oxidation–reduction followed by silsesquioxane coating method to improve the interfacial properties of carbon fibre/polyarylacetylene (CF/PAA) composites. The treatment method was divided into three phases, i.e., oxidation with oxygen plasma, reduction with LiAlH₄, and coating treatment with vinyl silsesquioxane (VMS–SSO). The fibre surface composition and functional group were analyzed using X-ray photoelectron spectroscopy (XPS). The polar functional groups, especially C–OH which could react with Si–OH on silsesquioxanes, were increased after redox reaction. VMS–SSO coating treatment imported vinyl groups which could react with PAA resin during PAA cure process. The surface morphology of carbon fibre was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The mechanical interfacial properties of the CF/PAA composites were characterized by short-beam bending testing method. Interlaminar shear strength (ILSS) of the CF/PAA composites in different treatment phases were increased by 31.7%, 28.8%, and 59.3%, respectively. The conclusion that oxidation–reduction followed by silsesquioxane coating treatment is an effective method to improve the interfacial properties of the CF/PAA composites can be drawn. This method can be used in other resin systems if the functional groups on silsesquioxane are changed according to those in resins.     

铁基非晶条带-玻璃纤维混杂复合材料力学特性

针对铁基非晶条带-玻璃纤维混杂增强树脂基复合材料,研究了表面处理、热处理对非晶条带力学性能的影响,在此基础上选取了适宜的树脂基体,制备了混杂复合材料,测试了基本力学性能并分析了破坏模式。结果表明：酸蚀表面处理对条带的拉伸性能影响很小,但改变了条带的表面形貌和表面能,从而提高了条带与树脂的粘结性能;混杂复合材料纵向拉伸弹性模量符合混合定律,横向拉伸弹性模量主要由非晶条带贡献,并且非晶条带的承载对混杂复合材料的横向拉伸强度起到了一定的作用;弯曲破坏和剪切破坏均产生受压侧纤维层与非晶条带的分层以及纤维断裂。     

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。     

Composites based on bimodal vinyl ester resins with low hazardous air pollutant contents

Vinyl ester (VE) resins with a bimodal distribution of molecular weights were prepared via methacrylation of epoxy monomers. Bimodal VE resins and neat polymers had viscosities and mechanical properties similar to that of commercial resins. E-glass composites were prepared and also found to have similar mechanical and thermo-mechanical properties relative to composites fabricated using commercial resins. However, the fracture toughness of the bimodal resins was superior to that of the commercial resins partially as a result of increased molecular relaxations that were manifested in a broader glass transition. Overall, bimodal resins allow for the use of low styrene content (33 wt%), while maintaining excellent thermal, mechanical, and fracture properties for the neat resins and composites.     

Effect of CuO nanostructure morphology on the mechanical properties of CuO/woven carbon fiber/vinyl ester composites

The effect of CuO nanostructure morphology on the mechanical properties of CuO/woven carbon fiber (WCF)/vinyl ester composites was investigated. The growth of CuO nanostructures embedded in the surface of woven carbon fibers (WCFs) was carried out by a two-step seed-mediated hydrothermal method; i.e., seeding and growth treatments with controlled chemical precursors. CuO nanostructural morphologies ranging from petal-like to cuboid-like nanorods (NRs) were obtained by controlling the thermal growth temperature in the hydrothermal process over a growth time of 12 h. The Cu²⁺/O⁻ ratio and the rate of reaction greatly influenced the formation of CuO nanostructures as self-assembled shapes on the crystal planes in the order L[0 1 0] > L[1 0 0] > L[0 0 1]. Morphological variations were analyzed by scanning electron microscopy, X-ray diffraction, and Brunauer–Emmett–Teller surface area analysis. The impact behavior, in-plane shear strength, and tensile properties of the CuO/WCF/vinyl ester composites were analyzed for different CuO NR morphologies at various growth temperatures and molar concentrations. The CuO/WCF/vinyl ester composites had improved impact energy absorption and mechanical properties because the higher specific surface area of CuO NRs grown as secondary reinforced nanomaterials on WCFs enhanced load transfer and load-bearing capacity.     

Effect of Cold Plasma Treatment on the Mechanical Properties of RTM Composites

Cold plasma technology was used to treat the surface of carbon fibers braided by PET in this paper and SEM was used to analyze the fracture microstructure of composite interlaminar shear stress (ILSS). The result shows that the surface polarity of carbon fibers was modified by cold plasma treatment, which increases the impregnation of PET braided carbon fibers during the process of resin flowing, improves the interfacial properties of RTM composites, and therefore enhances the mechanical properties of the KTM composites.