碳纤维的电聚合处理及其对复合材料性能的影响

一、引言 碳纤维电聚合表面处理是近年发展起来的一项新技术。所谓电聚合处理,就是在电场引发下使单体在碳纤维表面聚合,从而在碳纤维表面生成聚合物涂层。在电聚合中可以通过选用不同的单体和聚合条件来改变聚合物涂层的性质,以改善碳纤维复合材料(CFRP)的性能。电聚合处理有可能在碳纤维表面生成聚合物接枝,使聚合物涂层和碳纤维产生化学键接。同时,聚合物涂层内一些活性基团能与基体树脂中的官能团发生化学反应,这样就可大大提高碳纤维与树脂间的粘结强度。     

60Coγ-辐射接枝对粘胶基碳纤维的表面改性

为了提高粘胶基碳纤维与树脂的界面粘接性能,采用60Coγ-射线辐射接枝方法对粘胶基碳纤维进行表面改性,研究了接枝溶液种类和吸收剂量对接枝率和复合材料界面性能的影响,吸收剂量对碳纤维抗拉强度的影响,利用扫描电子显微镜分析了辐射接枝后碳纤维表面和复合材料剪切断口断裂形貌的变化.结果表明,环氧/丙酮溶液体系是碳纤维辐射接枝改性的理想溶液,在此溶液中辐射,当吸收剂量大于0.1 kGy时,纤维表面的接枝率为4.2%,复合材料的ILSS提高了20%以上;在合适的吸收剂量下辐射可提高碳纤维的抗拉强度;接枝后纤维表面粗糙度明显增大,与树脂的机械锲合作用增强.     

面向3D打印的连续碳纤维上浆工艺及其对复合材料性能的影响

对连续纤维增强热塑性复合材料(CFRTPCs)进行3D打印能够实现无模具快速制造,扩展增材制造的实际应用。为进一步提高3D打印连续碳纤维增强复合材料制件的性能,采用热塑性上浆剂对干碳纤维进行上浆处理,以尼龙6(PA6)为基体打印连续碳纤维增强复合材料,对比了上浆前后碳纤维表面性质及复合材料力学和界面性能。结果表明,上浆后碳纤维表面极性官能团增加,纤维与树脂浸润性改善;纤维表面粗糙度增加,纤维与树脂的机械结合力增强;上浆后碳纤维增强PA6复合材料较原始碳纤维增强PA6复合材料层间剪切强度提高42. 2%,层间结合增强,弯曲强度提高了82%,弯曲模量提高2. 46倍; 3D打印的上浆后碳纤维增强PA6复合材料试样断面上有明显纤维拔出现象,界面性能显著改善。     

苎麻纤维增强原位阴离子聚合尼龙6复合材料的制备及性能研究

以己内酰胺为单体,经热处理的苎麻纤维(RF)为增强材料,采用真空辅助树脂传递模塑成型工艺(VARTM)成功制备了苎麻纤维增强原位阴离子聚合尼龙6(APA6)复合材料.主要研究了热处理前后苎麻纤维表面官能团、结晶性能、力学性能和微观形貌的变化,并对复合材料的冲击断面、力学性能和热性能进行了考察.研究表明:当热处理温度为280℃时,苎麻纤维表面的羟基数量显著减少,结晶度略有降低,拉伸强度和模量有所下降,但苎麻纤维的形貌未有明显变化.RF/APA6复合材料中苎麻纤维与树脂的界面结合良好,与APA6相比,复合材料的拉伸强度略有提高,拉伸模量和弯曲性能得到明显提升,同时热稳定性显著提高.     

苎麻纤维增强原位阴离子聚合尼龙6复合材料的制备及性能研究

以己内酰胺为单体,经热处理的苎麻纤维(RF)为增强材料,采用真空辅助树脂传递模塑成型工艺(VARTM)成功制备了苎麻纤维增强原位阴离子聚合尼龙6(APA6)复合材料。主要研究了热处理前后苎麻纤维表面官能团、结晶性能、力学性能和微观形貌的变化,并对复合材料的冲击断面、力学性能和热性能进行了考察。研究表明:当热处理温度为280℃时,苎麻纤维表面的羟基数量显著减少,结晶度略有降低,拉伸强度和模量有所下降,但苎麻纤维的形貌未有明显变化。RF/APA6复合材料中苎麻纤维与树脂的界面结合良好,与APA6相比,复合材料的拉伸强度略有提高,拉伸模量和弯曲性能得到明显提升,同时热稳定性显著提高。     

炭纤维表面官能团异氰酸酯化及阴离子接枝尼龙6研究--(Ⅰ)接枝方法与表征

提出了炭纤维(CF)表面接枝的一种新方法。通过CF表面官能团的异氰酸酯化,利用异氰酸酯作为MC尼龙6聚合的活化剂,成功地通过阴离子接枝聚合方法制备了表面接枝尼龙6(PA6)的CF。扫描电子显微镜(SEM)结果表明．接枝了PA6的CF表面呈粗颗粒状形态与织构。X光光电子能谱(XPS)结果表明阴离子接枝PA6的CF表面N／C比例由0．0295提高到0．0573。称量法表明接枝率可达1．8％以上。     

^60Coγ—辐射接技对粘胶基碳纤维的表面改性

为了提高粘胶基碳纤维与树脂的界面粘接性能，采用^60Coγ—射线辐射接枝方法对粘胶基碳纤维进行表面改性，研究了接枝溶液种类和吸收剂量对接枝率和复合材料界面性能的影响，吸收剂量对碳纤维抗拉强度的影响，利用扫描电子显微镜分析了辐射接枝后碳纤维表面和复合材料剪切断口断裂形貌的变化。结果表明，环氧／丙酮溶液体系是碳纤维辐射接枝改性的理想溶液，在此溶液中辐射，当吸收剂量大于0．1kGy时，纤维表面的接枝率为4．2％，复合材料的ILSS提高了20％以上；在合适的吸收剂量下辐射可提高碳纤维的抗拉强度；接枝后纤维表面粗糙度明显增大，与树脂的机械锲合作用增强。     

γ射线辐照对碳纤维表面接枝改性的影响

为提高碳纤维/环氧树脂复合材料的界面粘结性能, 采用γ射线共辐照接枝方法对碳纤维表面改性, 利用X光电子能谱仪(XPS)、 扫描电子显微镜(SEM)、 电子万能材料试验机, 研究了在缩乙二醇丙酮溶液和环氧氯丙烷丙酮溶液中经200 kGy剂量的γ射线辐照接枝后, 碳纤维的表面化学元素及官能团组成、 表面形貌、 复合材料剪切断面形貌及其层间剪切强度(ILSS)的变化。研究表明, 缩乙二醇类接枝液的接枝效果较理想, 碳纤维接枝率达7%; 辐照处理碳纤维表面O/C比值和含氧官能团含量增加, 以此制备的碳纤维/环氧复合材料的ILSS提高, 最大提高率达31.2%; 同时还发现辐照接枝后的碳纤维表面粗糙度增大。     

碳纤维表面改性及对其复合材料性能的影响

采用γ射线辐照法、电化学聚合法改性碳纤维表面,研究了以三缩四乙二醇为接枝单体,在不同的辐照剂量下辐照处理碳纤维,以及电化学聚合衣康酸改性碳纤维。利用扫描电子显微镜、X光电子能谱仪、电子万能试验机研究了处理前后的碳纤维的表面形貌、复合材料的断面形貌、表面化学组成及复合材料层间剪切强度(ILSS)的变化。研究结果表明,2种处理方法都能有效提高碳纤维表面活性,与环氧树脂的浸润性提高,复合材料断面纤维拔出明显减少。在200kGy的辐照剂量下处理得到的碳纤维与环氧树脂复合材料的ILSS的提高幅度最大,达到31.2%。同时经电聚合处理后的碳纤维与环氧树脂复合材料的ILSS的提高幅度要大于经γ射线辐照处理后的试样,达到40%。     

环氧改性水性聚氨酯上浆剂对碳纤维/氰酸酯树脂复合材料界面性能的影响

使用自行合成的环氧改性水性聚氨酯(EWPU)上浆剂对碳纤维进行表面处理,主要研究了EWPU上浆剂对碳纤维表面及碳纤维/氰酸酯树脂复合材料界面性能的影响。采用扫描电镜(SEM)、傅里叶红外光谱(FTIR)、X射线光电子能谱(XPS)和静态接触角等表征方法对比研究了二次上浆处理前碳纤维(CF)和处理后碳纤维(MCF)的表面形貌、表面化学元素组成和浸润性的变化,并通过单纤维破碎实验和短梁剪切法,研究了EWPU上浆剂对碳纤维/氰酸酯树脂复合材料界面力学性能的影响。结果表明,经EWPU上浆处理后碳纤维表面O/C值增加了39.13%,表面活性官能团的含量增加了14.97%,碳纤维与树脂的初始和稳态接触角分别减小了19.41%和20.59%,碳纤维/氰酸酯树脂复合材料的单丝界面剪切强度和层间剪切强度分别增加了13.42%和14.29%。     

Cellulose fiber/poly(ethylene-co-methacrylic acid) composites with ionic interphase

Cellulose fiber/thermoplastic composites with ionic interphase were prepared from modified cellulose fibers and poly(ethylene-co-methacrylic acid) (PE-co-MA). The cellulose fiber was treated by using coupling agent or sodium hydroxide followed by introduction of ionic quaternary ammonium groups on the fiber surface, which was then compounded with the polymer having anionic groups. The effect of the ionic interface on the composite physical and thermal dynamic properties was investigated. An obvious improvement in mechanical strength of the ionic-interface composites was observed due to acid–base interactions. The improved adhesion could be ascribed to the interaction between cationic grafted groups at the cellulose fiber surface and the anionic groups in the PE-co-MA.     

Influence of cold remote nitrogen oxygen plasma treatment on carbon fabric and its composites with specialty polymers

The parameters controlling performance of a fiber-reinforced polymer composite are type of matrix and fibers, their amount, aspect ratio, fiber orientation with respect to loading direction, fiber–matrix interface, and processing technique. In the case of carbon fiber reinforcement, fiber–matrix interface has always been a serious concern, because of chemical inertness of carbon fibers toward matrix and hence efforts are continued to enhance the fiber–matrix adhesion. A recent technique of cold remote nitrogen oxygen plasma was employed for surface treatment of carbon fabric (CF) to enhance its chemical reactivity and mechanical interaction toward matrix material. Untreated and plasma treated CF were used as bidirectional reinforcement for developing high performance composites with various specialty polymer matrices such as Polyetherimide, Polyethersulfone, and Polyetheretherketone. Treated CF reinforced composites showed appreciable improvement in most of the mechanical properties, which varied with type of plasma, its dozing and matrix used. X-ray Photoelectron Spectroscopy confirmed improvement in O/C and N/C ratio indicating inclusion of Oxygen and Nitrogen on the surfaces of fibers due to plasma treatment, which was responsible for enhanced adhesion. Similarly, Fourier Transform Infrared–Attenuated Total Reflectance Spectroscopy indicated presence of ether, carboxylic, and carbonyl functional groups on the plasma-treated surface of fibers. Raman spectroscopy indicated slight distortion in graphitic structure of treated CF. Scanning Electron Microscopy also indicated changes in the topography of treated CF, indicating enhanced mechanical interlocking with matrix.     

Surface treatment of coir (Cocos nucifera) fibers and its influence on the fibers’ physico-mechanical properties

Coir, an important lignocellulosic fiber, can be incorporated in polymers like polyacrylate in different ways for achieving desired properties and texture. But its high level of moisture absorption, poor wettability and insufficient adhesion between untreated fiber and the polymer matrix lead to debonding with age. In order to improve the above qualities, adequate surface modification is required. In our present work, fiber surface modification by ethylene dimethylacrylate (EMA) and cured under UV radiation. Pretreatment with UV radiation and mercerization were done before grafting with a view to improve the physico-mechanical performance of coir fibers’. The effects of mercerization on shrinkage and fiber weight losses were monitored at different temperature and alkali concentration. We observed that, fiber shrinkage is higher at low temperature and 20% alkali treated coir fibers yielded maximum shrinkage and weight losses. It was found that higher shrinkage of the polymer grafted fiber showed enhanced physico-mechanical properties. The grafting of alkali treated fiber shows an increase of polymer loading (about 56% higher) and tensile strength (about 27%) than 50% EMA grafted fiber. The fiber surface topology and the tensile fracture surfaces were characterized by scanning electron microscopy and were found improved interfacial bonding to the modified fiber–matrix interface.     

Interface property of carbon fibers/epoxy resin composite improved by hydrogen peroxide in supercritical water

Carbon fibers were treated by hydrogen peroxide in supercritical water and the surface morphologies of treated carbon fibers were observed by atomic force microscopy. It was found that surface roughness of the treated carbon fiber was improved obviously. Furthermore, X-ray photoelectron spectroscopy (XPS) was used to analyze surface functional groups of carbon fibers. It was found that functional groups containing oxygen were significantly increased compared with untreated carbon fibers. The maximal interlaminar shear strength (ILSS) of treated carbon fibers/epoxy resin composite was 110.5 MPa, which was higher than 63.5 MPa for untreated carbon fibers/epoxy resin composite. It also indicated that interface property of carbon fibers/epoxy resin composite was improved by hydrogen peroxide in supercritical water.     

Investigation of structure,mechanical and tribological properties of short carbon fiber reinforced UHMWPE-matrix composites

Structural, mechanical and tribological properties of composite materials based on ultra-high molecular weight polyethylene reinforced with carbon fibers were investigated. The effect of surface modification of carbon fibers on the interaction at the fiber–matrix interface in UHMWPE based composites was studied. It was found that the thermal oxidation of carbon fibers by air oxygen at 500 °C can significantly enhance the interfacial interaction between the polymer matrix and carbon fibers. This allowed us to form composite materials with improved mechanical and tribological properties.     

石墨烯及其聚合物复合材料在锂离子电池中的应用研究进展

石墨烯的出现为设计和构建新型功能复合材料提供了广阔的空间,文中详细综述了石墨烯及其聚合物复合材料在锂离子电池中的研究进展。石墨烯是一种极有发展潜力的负极材料,储锂性能受到结构特征、含氧官能团和杂质原子等多种因素影响,导致储锂行为和机理较为复杂。将具有储锂活性的聚合物与石墨烯复合作为正极材料,储锂性能受到聚合物氧化还原的可逆性和复合结构等因素影响。聚合物还作为晶格匹配剂和交联剂,有利于提高石墨烯与氧化物复合的结构稳定性。最后指出,聚合物种类和制备方法的选择是以改善储锂性能为原则,有针对性和预见性地设计和制备高性能锂离子电池电极材料。     

Measurement of interfacial residual stress in SiC fiber reinforced Ni-Cr-Al alloy composites by Raman spectroscopy

Raman spectroscopy was used to measure Raman spectra of the inner SiC fibers and surface C-rich layers of SiC fibers, composite precursors and SiCf/Ni-Cr-Al composites. The residual stresses of the inner SiC fibers and surface C-rich layers were calculated, and the effect of the(Al + Al_2O_3) diffusion barrier layer on the interfacial residual stress in the composites was analyzed in combination with the interface microstructure and energy disperse spectroscopy(EDS) elements lining maps. The results show that the existence of(Al + Al_2O_3) diffusion barrier improves the compatibility of the SiCf/Ni-Cr-Al interface,inhibits the adverse interfacial reaction, and relieves the residual stress inside SiC fibers and at the interface of composite material. Heat treatment can reduce the residual stress at the interface. As the heat treatment time increases, the residual stress at the interface decreases.     

Electrophoretic deposition of aramid nanofibers on carbon fibers for highly enhanced interfacial adhesion at low content

Here, an anodic electrophoretic deposition was adopted to facilitate the large-scale uniform coating of nano-fillers onto carbon fibers to enhance the interfacial properties between carbon fibers and epoxy matrix. As interface–reinforcing materials, aramid nanofibers were introduced because of their superior mechanical properties and epoxy matrix-friendly functional groups. Furthermore, aramid nanofibers can be readily coated on carbon fibers via electrophoretic deposition because they are negatively-charged in solution with high electrical mobility. Finally, aramid nanofiber-coated carbon fibers showed significantly improved interfacial properties such as higher surface free energy and interfacial shear strengths (39.7% and 34.9% increases, respectively) than those of a pristine carbon fiber despite a very small amount of embedding (0.025 wt% of aramid nanofibers in a carbon fiber), and the short beam strength of the laminated composite prepared with the aramid nanofiber-coated carbon fibers was also improved by 17.0% compared to a non-modified composite.     

改性碳纳米管处理碳纤维的效果表征

采用浓硫酸/浓硝酸氧化处理多壁碳纳米管(MWCNTs),再将氧化后的碳纳米管与硅烷偶联剂(KH560)进行接枝,制备了硅烷偶联剂表面化学修饰的MWCNTs。在此基础上,将改性前后的碳纳米管分散在环氧树脂体系中,涂覆处理碳纤维。研究处理前后碳纤维力学性能和界面性能的变化。通过红外光谱(FTIR)和透射电镜(TEM)分析,表明KH560已成功接枝到多壁碳纳米管上;通过分散性实验证明了改性后的碳纳米管分散性提高;对处理后的碳纤维进行力学性能测试,并用扫描电镜(SEM)观察分析断面形态变化,结果表明,当碳纳米管的含量为0.5%时,改性碳纳米管处理的碳纤维拉伸强度和拉伸模量分别提高23.83%和7.11%,界面性能增强。     

石墨烯/功能聚合物复合材料

常规的聚合物与石墨烯组成复合材料时，聚合物的引入经常会损害石墨烯的一些性能，如降低石墨烯材料本征的高导电性、导热能力、高比表面积等，因此石墨烯/聚合物复合材料的应用也受到颇多限制。如果基于不同的应用，通过设计或选用具有特定性能的功能聚合物，可以有针对性地增强石墨烯某些特定的性质，提高石墨烯/聚合物复合材料的应用性能，减弱甚至消除复合材料应用的限制性。本文基于上述这一功能聚合物定义范畴，以石墨烯/聚合物复合材料中石墨烯的维度进行分类，包括三维网络结构石墨烯、二维薄膜结构石墨烯、一维纤维结构石墨烯，介绍并讨论石墨烯/功能聚合物复合材料的制备方法和当前的应用进展，并分析存在的问题及发展前景。