电化学氧化对碳纤维表面电化学性质的影响

碳纤维表面呈现化学惰性,缺乏活性官能团,限制了碳纤维作为电化学分析电极的应用.目前,许多手段被用于碳纤维的表面改性处理.采用电化学氧化方法,在磷酸溶液中对碳纤维进行了处理,并进行了红外光谱和循环伏安试验.结果发现:处理后碳纤维的表面接上了活性官能团,大量活性碳原子被剥离出来.在K4Fe(CN)6加KCl、FeSO4加HClO4两组混合溶液体系中的电化学响应明显改善,适合作为电化学分析电极.     

“点击”化学法聚合物包覆纳米二氧化硅的研究

目的为了提高纳米二氧化硅与树脂的相容性,采用"点击"化学法研究表面接枝聚合物。方法利用普通自由基聚合制备的聚(甲基丙烯酸甲酯-马来酸酐)和聚(甲基丙烯酸甲酯-甲基丙烯酸缩水甘油酯),分别与丙炔醇和叠氮钠反应从而在分子链上引入多个炔基和叠氮基,然后与叠氮基改性的纳米二氧化硅粒子进行"点击"化学反应实现纳米二氧化硅包覆改性,并通过热重分析、红外光谱分析以及扫描电镜进行结构表征。结果聚合物接枝到了纳米二氧化硅表面,包覆第一层聚合物后,二氧化硅分散性明显提高;包覆第二层聚合物后,分散性有所下降。结论通过在纳米二氧化硅表面包覆聚合物,可以明显提高其分散性能。     

纳米二氧化钛表面改性及其在聚氨酯涂层中的分散性质

采用长链烷烃和微胶囊方法对纳米TiO2(锐钛型,粒径20nm) 进行表面改性,利用傅里叶红外光谱(FTIR)和热重分析(TGA)分别研究了改性纳米粉体的表面化学结构及接枝率,结果表明:改性纳米TiO2粉体表面成功接枝了高分子聚合物,接枝率分别为5%和12%.将改性纳米TiO2粉体(质量分数为1%～3%)与双组分聚氨酯涂料进行复合,制备了纳米TiO2/聚氨酯复合涂料,并利用扫描电子显微镜(SEM)对纳米复合涂层进行了微观检测,结果表明:微胶囊改性的纳米TiO2在涂层中的分散性最好.     

碳纤维表面接枝纳米 SiO2的工艺研究

采用偶联剂交叉处理法,成功地在碳纤维表面接枝了纳米SiO2粒子。对制备过程中各步获取的样品进行了表面形貌表征和傅里叶红外光谱分析,并讨论了纳米SiO2的浓度、反应温度和时间等实验条件对接枝效率的影响。结果表明:当纳米SiO2的浓度为4%,反应温度为100℃,反应时间为4 h时,接枝效果最佳,接枝率为5.69%。     

硅烷偶联剂链长对纳米 TiO2表面改性的影响

采用具有不同链长的硅烷偶联剂KH570和KH171分别对纳米TiO2粒子进行了表面改性。采用红外光谱(FT-IR)、热重分析(TG)、透射电镜(TEM)和润湿性实验等测试。结果表明:硅烷偶联剂有机链长的空间位阻效应对纳米粒子改性起关键作用。TEM表明经长链的KH570改性纳米TiO2分散效果更佳;热重分析和润湿性实验表明当长链KH570用量为10%时,纳米粒子表面接枝率和水接触角均达到最大,分别为8.05%和76.6°;红外光谱表明长链的KH570键合强度较KH171大。     

混氧等离子体射流对CFRP表面性质及粘接强度的影响

目的 探究不同氧气含量下大气压混氧等离子体射流特性,分析其对碳纤维复合材料（CFRP）表面理化性质的影响,研究其改善表面浸润性及粘接强度的机理。方法 采用大气压介质阻挡放电（DBD）,产生氦氧混合等离子体射流,对CFRP表面进行处理,研究了不同氧气体积分数射流对CFRP表面的作用效果,确定了相对较佳的氧气体积分数。借助接触角测量仪、扫描电子显微镜（SEM）、原子力显微镜（AFM）和X射线光电子能谱仪（XPS）等表面分析手段,对处理前后CFRP表面的润湿性、微观形貌、粗糙度和化学成分等进行测试分析。采用环氧树脂胶粘剂,分别对射流处理前后的CFRP与铝合金表面进行粘接,并测试不同表面的粘接强度。结果 随着氧气体积分数的增加,射流长度变短,温度逐渐下降。氧气处理所得表面的浸润性相比未混氧射流处理所得表面的浸润性明显提高。当氧气体积分数为0.75%时,所得表面浸润性相对最好。与纯氦等离子体射流相比,混氧射流处理后,表面环氧树脂铺展速率更高,说明表面对胶粘剂的亲和性相对较好,所得表面粗糙度也相对更低。XPS测试结果表明,混氧射流处理所得表面含氧官能团含量更高,表面能相对较高,故表面润湿性较好。结...     

碳纤维复合贴片的界面行为研究

采用低温等离子体法对碳纤维进行表面处理,并在微波固化条件下将碳纤维与环氧树脂复合成形,制得碳纤维复合贴片.采用X射线光电子能谱仪对碳纤维表面的元素组成进行了表征,采用扫描电镜和能量散射光谱(EDS)对碳纤维/树脂界面区的形貌和元素分布进行了表征.结果表明:碳纤维经处理后,其表面氨基官能团的含量增大,有利于纤维与树脂的化...     

铜粉表面包覆硅烷偶联剂改性研究

用红外光谱分析技术研究硅烷偶联剂在铜粉表面的接枝情况,对涂层的导电性能进行测试,确定了偶联剂的处理工艺。实验表明,硅烷偶联剂可以很好地在铜粉表面形成包覆层,直接添加偶联剂比预处理效果要好。     

溶胶凝胶法包覆莫来石提高金刚石热性能的研究

以硝酸铝、异丙醇铝和正硅酸乙酯为原料,以去离子水为溶剂,采用溶胶凝胶法在金刚石表面包覆莫来石涂层,通过扫描电子显微镜(SEM)、热重分析(TG)、傅里叶变换红外光谱(FT-IR)等测试方法,对包覆涂层后的金刚石表面形貌、结构以及热性能等进行了分析。结果表明:采用溶胶凝胶法包覆后,在金刚石表面可以形成连续的莫来石涂层,化学组成属典型的莫来石(3Al2O3·2SiO2)结构。包覆莫来石涂层改善了金刚石表面的化学结构和热性能,在出现明显的失重速率加快之前几乎没有出现热失重现象,使金刚石的抗氧化温度提高了75℃。     

甲基丙烯酸甲酯原位聚合包覆铜金粉

为了提高铜金粉的耐腐蚀性能,采用甲基丙烯酸甲酯(MMA)原位聚合对铜金粉进行了有机聚合物的包覆,以吸光度、光泽度与接枝率为主要评价指标,探讨单体用量、引发剂用量、偶联剂用量对原位聚合过程的影响,并采用IR、SEM和XRD等手段对包覆前后的铜金粉进行表征.结果表明:当m(MMA)/m(Cu)=0.2时,表面包覆PMMA后的铜金粉具有良好的耐腐蚀性能与光泽度;当m(AIBN)/m(MMA)=0.05时,耐腐蚀性能最佳,而此时的接枝率也达到最高点,即耐腐蚀性能与接枝率之间存在一定的对应关系;偶联剂MPS的加入有利于提高铜金粉的耐腐蚀性能,这是由于其分子结构中具有甲氧基(OCH3)与碳碳双键(C＝C),形成具有特殊功能的"分子桥"所致,从而将铜金粉与PMMA通过化学键牢固地结合起来.     

Tensile Properties of Polyimide Composites Incorporating Carbon Nanotubes-Grafted and Polyimide-Coated Carbon Fibers

The tensile properties and fracture behavior of polyimide composite bundles incorporating carbon nanotubes-grafted (CNT-grafted) and polyimide-coated (PI-coated) high-tensile-strength polyacrylonitrile (PAN)-based (T1000GB), and high-modulus pitch-based (K13D) carbon fibers were investigated. The CNT were grown on the surface of the carbon fibers by chemical vapor deposition. The pyromellitic dianhydride/4,4′-oxydianiline PI nanolayer coating was deposited on the surface of the carbon fiber by high-temperature vapor deposition polymerization. The results clearly demonstrate that CNT grafting and PI coating were effective for improving the Weibull modulus of T1000GB PAN-based and K13D pitch-based carbon fiber bundle composites. In addition, the average tensile strength of the PI-coated T1000GB carbon fiber bundle composites was also higher than that of the as-received carbon fiber bundle composites, while the average tensile strength of the CNT-grafted T1000GB, K13D, and the PI-coated K13D carbon fiber bundle composites was similar to that of the as-received carbon fiber bundle composites.     

Composition and properties of functional groups on surface of carbon sorbents modified by aminocaproic acid

The composition and properties of functional groups on the surface of carbon sorbents modified with aqueous solutions of aminocaproic acid of different concentrations were studied using physicochemical analysis methods: including acid-base titration, the Kjeldahl method, scanning electron microscopy, X-ray microanalysis, and X-ray photoelectron spectroscopy. The initial carbon sorbent was shown to have almost no functional groups on its surface. It was ascertained that the surface functionalization of carbon sorbent results in a change in microstructure and an increase in the amount of oxygen- and nitrogen-containing groups with increasing concentration of the modifying agent followed by its further polycondensation on the surface. According to the XPS data, the formation of the bond between aminocaproic acid and the carbon surface of sorbents occurs via a carboxylic group.     

Influence of aging behavior of Armos fiber after oxygen plasma treatment on its composite interfacial properties

This work concerns the aging behavior of Armos fiber and Armos fiber reinforced poly (phthalazinone ether sulfone ketone) (PPESK) composite after oxygen plasma treatment. Armos fiber surface chemical composition, surface morphology and roughness, and surface wettability as a function of storage time in air after oxygen plasma treatment were measured by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and dynamic contact angle analysis (DCAA) system, respectively. The fiber surface aging behavior could be detected obviously in chemical composition and surface wettability, whereas the surface morphology and roughness remained nearly stable after storing in air as long as 10 days after oxygen plasma treatment. The effects of surface aging behavior after oxygen plasma treatment on Armos fiber reinforced PPESK composite interfacial properties were evaluated by interlaminar shear strength (ILSS) test and humid resistance measurement. It was found that the values of ILSS reduced and the composite humid resistance properties decayed. The polar functional groups that were reoriented from the surface into the bulk of the fibers or moved away from the fiber surfaces, maybe responsible for the weak interfacial strength between the fiber and the matrix in composite system.     

Preparation and Characterization of Carbon Microfiber Through Shear Pulverization Using Pan-Mill Equipment

Carbon microfiber was prepared through shear pulverization using the self-designed pan-mill type equipment at ambient temperature from short carbon fiber (CF). The effects of shear stress on structure transformations, particles size, microfiber morphology, surface functional groups and crystalline properties during pulverization were studied by laser diffraction particle size analyzer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), x-ray photoelectron spectroscopy (XPS) and wide-angle x-ray diffraction (WAXD), respectively. SEM analysis indicated that CF was milled into microfiber due to the strong shear and squeezing force. The average particle size of carbon microfiber was reduced to 12.7 μm and specific surface area was increased to 0.6 m²/g after 40 milling cycles. FT-IR and XPS analyses showed that the oxygen-containing groups increased after shear pulverization, and WAXD results illustrated that shear stress offered by mill discs had an obvious damage on the crystal structure of CF, leading to a decrease of crystallinity. Thermal analysis showed that carbon microfiber exhibited good thermal stability. The pan-milling shear pulverization technique is an environment-friendly and efficient method for preparing carbon microfiber.     

自组装制备准一维金纳米复合导线

为了获得性能优异的微电子材料,通过化学镀和自组装制备了平均直径小于50 nm的准一维金纳米复合导线.通过实验证实了金纳米线的形成机制,即纳米金复合导线是纳米金微粒在巯基化的碳纳米管表面通过自组装而形成的.碳纳米管分别依次与浓硝酸和浓硫酸的混酸(1:4)、LiAlH4、PBr3和NaHS反应,可得到活性基团巯基修饰的碳纳米管.分别用XPS、TEM、XRD等对实验结果进行了表征.     

Nitrogen plasma modification of viscose-based activated carbon fibers

Viscose-based activated carbon fibers (VACFs) were treated by a dielectric-barrier discharge plasma at different conditions. Nitrogen was used as the feed gas to create nitrogen radicals. The textural characteristics were analyzed by SEM, BET and XRD. The surface chemical functional groups were analyzed by XPS. The results show that after nitrogen plasma modification (NPM), the external surface of the VACFs was etched and became rougher, the surface area and pore volume decreased, the average micropore width barely changed, the PSD of the VACF became narrower and the graphitic crystallites of VACF had been destroyed slightly. XPS revealed that NPM could remarkably change the distribution of the oxygen functional groups on the VACFs surface and there were more nitrogen atoms incorporated into the aromatic ring. A tentative explanation for the modification process is proposed.     

Surface study of composite photocatalyst based on plasma modified activated carbon fibers with TiO2

Composite photocatalyst was prepared by the nitrogen plasma modification of active carbon fibers (ACF) loaded with TiO₂ using a tetrabutyl titanate hydrolyzing process. The surface morphology was characterized by SEM. The specific surface area and the pore size distribution of ACF were compared by N₂ adsorption before and after modification loaded TiO₂. The surface chemical functional groups and the performance of photocatalyst were investigated by XPS and formaldehyde decomposition respectively. The results show that after carrier surface nitrogen plasma modification, the surface morphology of composite photocatalyst barely changed, the surface area and pore volume decreased slightly, XPS revealed that nitrogen plasma modification could remarkably change the distribution of the oxygen functional groups on the carrier surface and adsorbing oxygen species on the surface of the composite photocatalyst increased. The efficiency of formaldehyde photocatalysis purification was improved by modification.     

PBO纤维表面改性处理的研究进展

聚对苯撑苯并二噁唑(PBO)纤维因其比强度高、比模量高、耐热性好、阻燃性好以及优异的介电性能,现已在安全防护、建筑汽车等领域得到广泛应用。由于PBO纤维表面光滑、化学惰性,导致其与基体树脂界面结合差,进一步影响复合材料的整体性能,这大大限制了PBO纤维优异综合性能的发挥,所以对PBO纤维表面进行改性处理显得尤为重要。介绍了近年来国内外针对PBO纤维不同表面改性方法及对应复合材料性能改善程度的研究进展,从PBO纤维改性方法的分类入手,阐述了各种方法的基本原理。通过对这些处理方法的比较,阐述了国内PBO纤维表面改性的研究进展,指出了国内外在PBO纤维表面改性处理上的差距,为未来的发展方向提供了参考。PBO纤维表面改性方法包括化学刻蚀法、等离子体处理、表面涂层法、化学接枝法、紫外刻蚀法、上浆剂处理等。各种改性技术各有利弊,在选择改性方法时,理应考虑达到工艺快捷有效、经济环保和无损纤维性能等指标。未来,在PBO纤维表面改性的处理方法领域,将逐步向绿色环保的上浆剂处理方向发展。