A novel method for coating of carbon nanotube on cellulose fiber using 1,2,3,4-butanetetracarboxylic acid as a cross-linking agent

Carbon nanotubes (CNTs) were coated by the exhaustion method and stabilized on a cotton surface using 1,2,3,4-butanetetracarboxylic acid (BTCA) as a crosslinking agent and sodium hypophosphite (SHP) as a catalyst. The Influence of CNTs on the performance of the cellulose fiber was investigated using Fourier transform infrared spectrophotometer (FTIR), thermo-gravimetric analyzer, scanning electron microscope (SEM), zeta potential analyzer, reflectance spectroscope, wrinkle recovery tester and bacteriological culture tube. The possible interactions between CNTs, the cross-linking agent and cellulose functional groups at the surface were elucidated by FTIR spectroscopy. The results indicated that the stabilized CNTs modify the surface of the fibers and increase the thermal stability of the substrate. SEM showed a uniform coating of CNTs on the fiber surface.     

Highly conductive polymer composites based on controlled agglomeration of carbon nanotubes

This paper reports an innovative approach to enhance electrical conductivity of fiber composites based on non-conductive fiber and polymer matrix. The dispersion of carbon nanotubes (CNTs) is carried out using a fiber sizing agent which contains uniformly distributed CNTs. The infusion of the sizing agent into the fiber preform prior to resin infusion gives rise to high agglomeration of CNTs on the fiber surface and results in electrical conductivities of 2-3 orders of magnitude higher than those of specimens prepared by a calendering approach.     

戊二醛交联改性再生纤维素纤维的研究

以氯化1-丁基-3-甲基咪唑离子液体为溶剂对木质纤维素进行溶解并纺丝,得到再生纤维素纤维,再使用戊二醛对再生纤维素纤维进行交联改性,研究其交联改性条件对再生纤维素纤维力学性能的影响。结果表明:经戊二醛交联后,再生纤维素纤维的断裂强度有明显的提高;在戊二醛质量分数为4%,反应温度为50℃,反应时间为30 min的交联条件下,所得再生纤维素纤维的断裂强度为3.2 cN/dtex。     

Crosslinking cotton with formaldehyde in phosphoric acid

Cotton print cloth was treated with a solution of formaldehyde in concentrated orthophosphoric acid (a strong cellulose swelling agent). The treatment produces a crosslinked cotton with extremely high wet wrinkle recovery and moisture absorptivity, and very low dry wrinkle recovery. The variations in physical properties are explained in terms of crosslink distribution throughout the fiber and specifically by differences in interlamellar and intralamellar crosslinking. Data on the chemical and physical properties of the fabric as well as electron micrographs of fiber cross-sections are presented and compared or contrasted with data from similar treatments employing other solvents such as water (a moderate swelling agent), acetic acid (a weak swelling agent), and sulfuric acid (a solvent which restricts crosslinking to the periphery of the fiber). Although the treatment causes extensive fiber swelling, it produces very little change in crystallinity and no change in crystal lattice type. Also discussed are the effects of combining this wet crosslinking and conventional dry-cure crosslinking with methylol amides in a two-stage process, in which the wet crosslinking is used either as a pretreatment or as an aftertreatment.     

离子交换纤维微观形貌特点及结构修饰研究

利用比表面积测试仪、扫描电子显微镜等物理化学方法对颗粒与纤维状离子交换剂的链间交联与微观形貌进行了研究,通过刚性交联剂对聚丙烯-苯乙烯-二乙烯基苯(PP-ST-DVB)离子交换纤维骨架结构进行了修饰改造。结果表明:离子交换纤维由于不能通过交联剂与致孔剂参与下的单体聚合构建具有丰富微孔的高分子骨架,所以不存在丰富孔结构和高比表面积特征,其内部为连续凝胶相结构;外比表面积大、传质距离短、交联键分布均匀是其反应动力学和渗透压稳定性能优异的主要原因;刚性交联剂在PP-ST-DVB纤维上的附加交联反应使其比表面积从原来的0.5 m~2/g提高到200 m~2/g以上,附加交联反应所形成的分子尺度微孔孔径分布窄,具有超高交联树脂的结构特点。     

碳纳米管在炭纤维表面的可控自组装

采用催化化学气相沉积法将碳纳米管(CNTs)原位生长于炭纤维(CF)表面并自组装成不同形貌的CNTs/CF杂化结构。使用扫描电子显微镜、拉曼光谱仪对制备的纳米/微米杂化结构进行微观形貌分析和结构表征。结果显示,随着温度的升高,碳纳米管在炭纤维表面由均匀分布状态转变为取向生长状态,并且长度及石墨化程度均不断增加。结合碳纳米管结构参数的变化,使用纳米悬臂梁模型解释了这一杂化结构的形成机理。模型分析表明,杂化结构的形貌转变是由不同温度下在炭纤维表面生长的碳纳米管的结构参数不同所造成的,因此可以通过调整相关结构参数控制碳纳米管在炭纤维表面的自组装过程。     

碳纳米管和偶联剂协同作用对热塑性复合材料力学性能的影响

将碳纳米管（CNTs）和硅烷偶联剂（AMEO）分散至纤维表面,制备聚芳硫醚（PAS）/玻璃纤维布/CNTs/AMEO复合材料,并探究复合材料的表面形貌和力学性能。结果表明：未经偶联剂处理的体系中,CNTs与纤维的结合性较弱。将CNTs进行羧化和偶联剂处理,能够提高CNTs和纤维之间的结合强度,提升纤维与PAS之间的应力传递,进一步提高复合材料的力学性能。当AMEO加入量为400、800、1 200、1 600μL/gCNTs,复合材料的拉伸强度分别为352、381、403、390 MPa,弯曲强度分别为380、414、443、478 MPa。由此得出,CNTs和AMEO协同作用明显提高复合材料的力学性能。     

交联剂对聚醚酰胺弹性纤维力学性能的影响

采用两步法工艺路线,以PA6齐聚物、聚醚和少量交联剂为原料共聚合成聚醚酰胺热塑性弹性体(TPAE)。对TPAE进行模拟纺丝,对初生纤维进行拉伸和热定型。测定了纤维的力学性能。利用WAXD分析了交联剂对TPAE结晶性能的影响,讨论了纤维弹性及回复率与纺丝条件、交联剂用量的关系。结果表明,随交联剂含量的增加,拉伸丝较初生丝的结晶度提高幅度小,交联剂的化学交联作用明显。交联剂的引入使TPAE纤维断裂强度和弹性回复率提高,断裂伸长率降低,交联剂质量分数(相对PA6)为0.7%时,TPAE纤维的弹性回复率可提高到95%以上。     

Crosslinking of cotton in the presence of poly(vinyl alcohol). Analysis and composition of products

The spectrophotometric method developed by Finley for the determination of poly(vinyl alcohol) in paper coatings has been adapted for analysis of cotton fabrics crosslinked with finishes containing a poly(vinyl alcohol) additive. The effect of time and pH of hydrolysis on the analysis, and the dependency of the durability of the poly(vinyl alcohol) on the crosslinking agent are established. Evidence of chemical attachment to the cellulose of the cotton fiber through the crosslinking agent is offered.     

交联羧甲基化水葫芦纤维研制及其吸水与保水性能考察

以水葫芦纤维为原料,在乙醇、KOH碱性溶液中,以氯乙酸为醚化剂,制备了羧甲基化水葫芦纤维.并用FeCl3作交联剂,制得交联羧甲基化水葫芦纤维基吸水剂.通过FT-IR,SEM进行化学和表面结构表征、通过滴定法测定羧甲基纤维素的含量、通过称量法测定水葫芦基吸水剂在蒸馏水和典型的化肥液中的吸水率.考察了KOH、氯乙酸、交联剂用量以及反应温度对吸水率的影响,并进一步考察了水葫芦基吸水剂对土壤的保水性能.结果表明:水葫芦纤维、氯乙酸及KOH的适宜质量比为1∶1.25∶1.05;在60 ℃醚化2.0 h,接着在22℃用0.45 ％(wt)的FeCl3(相对羧甲基化水葫芦纤维)交联,所得交联羧甲基化水葫芦纤维基吸水剂在蒸馏水中的吸水率可达78 mL·g-1,在弱电解质(尿素)溶液中的吸水率略有下降、而在强电解质(氯化钾和碳酸铵)溶液中的吸水率明显下降;含5％交联羧甲基化水葫芦纤维基吸水剂的泥土,其保水率明显提高.     

Growth of carbon nanotubes on carbon fibers using the combustion flame oxy-acetylene method

Multi-walled carbon nanotubes (MWCNTs) were directly grown on carbon fibers (CFs) using the combustion flame oxy-acetylene method. Ferrocene deposited on the fiber surface acts as a catalyst for carbon nanotubes (CNTs) growth. The effects of ferrocene concentration on the morphology of the CNTs coating were investigated. Growth temperature ranges from 500 to 650 °C at atmospheric pressure, while growth surface is a continuous 10 × 1000 mm² tape. CNTs are produced with a dense entanglement, covering the CFs uniformly. Tube outer diameters are in the range of 20–40 nm. Tube length is quite long (about 4–5 μm) and uniform. Particularly, growth times are very short: about 0.3–0.6 s. Growth morphology and other characteristics of the as-grown tubes were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy dispersive X-ray (EDX) and by Raman spectroscopy.     

Novel carbon‐nanotube‐based organogels as candidates for oil recovery

A simple method for synthesis of novel organogels based on multiwalled carbon nanotubes (MWCNTs) is reported. Three classes of organogels were synthesized by crosslinking polymerization of dodecyl methacrylate with various weight percentages of 1,4‐butanediol dimethacrylate, vinyl‐group‐modified MWCNTs or pristine MWCNTs in the presence of 2,2‐azoisobutyronitrile as initiator. In this reaction, the carbon nanotubes (CNTs) served simultaneously as an adsorbent, a comonomer and a crosslinking agent. The oil‐absorbent containing CNTs showed much higher swelling capacity in oil and organic solvents compared with that without CNTs. Therefore, CNT‐based organogels can be introduced as a promising candidate for environmental protection and oil recovery. © 2012 Society of Chemical Industry     

Influence of foaming and carbon nanotubes on sound transmission loss of wood fiber‐low density polyethylene composites

The aim of this study was to investigate the effect of carbon nanotubes (CNTs) and foaming on sound transmission loss (STL) of wood fiber‐low density polyethylene composite. For this purpose, low density polyethylene, wood fiber, foaming agent, coupling agent and modified CNTs were mixed in an internal mixer to produce test samples. The standard circular samples were produced by using compression molding method in a hot press machine. Sound transmission loss was measured by an impedance tube. Results showed that the use of CNTs improved the foam morphology in the composites. Foaming and the use of CNTs improve the STL of composites (especially at medium and higher frequencies) and the highest STL was obtained for wood fiber/LDPE foamed composites containing 1% CNT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45096.     

Acetone sensing and modeling through functionalized Ag-catalysts and CNTs via low cost metal-organic framework-derived ZnO nanostructures

Cost-effective synthesis, portability, quick response and fascinating features of semiconducting metal oxide sensors have drawn much accredited to be utilized in wide variety of potential sensing applications. Herein, flexible acetone sensor was fabricated through spray coating method using different conductive inks of carbon nanotubes (CNTs), zinc oxide (ZnO) and silver (Ag) nanoparticles solutions on cellulose paper. Morphological analysis revealed the fiber like morphology of cellulose over which CNTs, ZnO and Ag nanoparticles are uniformly distributed. The energy dispersive X-ray spectroscopic analysis was performed to observe the elemental composition in the as-prepared samples. The recovery time toward acetone was greater for CNTs/Ag acetone sensor at 95% as compared to CNTs/ZnO/Ag sensor. Additionally, sensing time of the samples towards acetone was measured and the observed response time was greater for CNTs/ZnO/Ag (0.52 s) acetone sensor as compared to CNTs/Ag sensor (0.41 s). Hence, CNTs/ZnO/Ag can be easily employed for sensing applications due to quick response.     

Synthesis of hybrid ZnO/CNTs nanoparticles and their reinforcement in nylon‐6 polymer fibers

In this investigation, in situ synthesis of zinc oxide nanoparticles in the presence of multiwalled carbon nanotubes (CNTs) have been carried out using a sonochemical technique. Zinc(II)acetate was used as a source of ZnO in the presence of ethylene glycol (EG) to obtain zinc oxide (ZnO) nanoparticles. The synthesized hybrid ZnO/CNTs nanoparticles were used as reinforcements to enhance the mechanical, thermal and UV absorbing properties of Nylon‐6 composite fibers. The polymer nanocomposites (PNC) were fabricated by dry mixing Nylon‐6 polymer powder with the ZnO/CNTs hybrid nanoparticles as the first step, then followed by the drying and melt extrusion process of fiber materials in a single‐screw extruder. The extruded fibers were stretched and stabilized using a godet set‐up and wound on a Wayne filament winder machine. The hybrid ZnO/CNTs infused Nylon‐6 composite fibers were compared with commercial ZnO, CNTs infused Nylon‐6 composite fibers and neat Nylon‐6 fibers for their structural and thermal properties. The morphological characteristics of ZnO/CNTs nanoparticles were carried out using X‐ray diffraction and transmission electron microscopy (TEM) techniques. The Nylon‐6 PNC fibers which were of ～80 μ size were tested mechanically. The tensile tests revealed that failure stress of the 1% infused ZnO/CNTs Nylon‐6 PNC fibers is about 73% higher than the neat extruded Nylon‐6 fiber and the improvement in the tensile modulus is 377.4%. The DSC results show an increase in the glass transition temperature and crystallization for ZnO/CNTs infused Nylon‐6 PNC fibers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effects of nitrogen-doped carbon nanotubes on the discharge performance of Li-air batteries

Carbon nanotubes (CNTs) and nitrogen-doped carbon nanotubes (N-CNTs) were synthesized using a floating catalyst chemical vapor deposition method and characterized by scanning electron microscopy (SEM), transmission electron microscopy, Raman and X-ray photoelectron spectroscopy. The study found that the as-prepared CNTs and N-CNTs showed different discharge capacity as cathode materials in Li-air battery. To further study the reason why N-doping improves the electrochemical performance exceptionally, the discharge products on the two kinds of nanotubes were detected by SEM, XRD and Raman. SEM study showed, for the first time, that more uniform distribution of discharge products on the surface of CNTs arising from N-doping affected the boost of discharge capacity, a result which was discussed in detail. In comparison to non-doped CNTs, nitrogen doping was considered to be a promising way to improve the performance of carbon based cathode material for Li-air batteries.     

Effect of carbon nanotube length and density on the properties of carbon nanotube-coated carbon fiber/polyester composites

Carbon nanotubes (CNTs) have been synthesized on the surface of carbon fiber/fabric using catalytic chemical vapor deposition (CVD) at a temperature of 550 °C. A coating of Ni catalyst on the fiber surface is applied using the electroless dip coating method. The dependence of the length and quantity of CNTs on the growth time is studied by varying the run time of the CVD reactor from 5 to 25 min. Scanning electron microscopy shows good coverage of the carbon fiber surface by the CNTs. It is observed that both the length and density of CNTs are functions of the growth time. Up to a critical growth time, both the storage modulus and the interfacial shear stress of CNT-coated carbon fiber/polyester composites are seen to increase substantially.     

Water-Soluble Carbon Nanotubes from Bitumen Waste: Synthesis, Functionalisation and Derivatisation for its Use as Superabsorbent

A simple method for the preparation of carbon nanotubes (CNTs) from bitumen waste and their derivatisation with polyacrylamide was achieved. Synthesised CNTs were functionalised in the presence of dilute nitric acid followed by derivatisation with polyacrylamide using the mixture of potassium persulphate-ferrous ammonium sulphate as a redox initiator and N,N′-methylene-bis-acrylamide as a crosslinking agent. The functionalisation and derivatisation of the CNTs were confirmed through Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. The effect of derivatisation on the thermal properties of the CNTs was studied by thermogravimetric analysis, differential thermogravimetric analysis and differential thermal analysis. The crosslinked derivatised product, CNT-cl-poly(AAm), was thermally more stable than the functionalised CNTs. The water-absorption capacity of the derivatised CNTs was investigated in deionised water as a function of time, temperature and pH of the swelling medium. CNT-cl-poly(AAm) was found to be an efficient water-absorption device with the maximum absorption capacity of 476 %.     

The effect of acetylation on the crystallinity of BC/CNTs nanocomposite

BACKGROUND: Bacterial cellulose (BC) synthesized by Acetobacter xylinum has been shown to be a potential matrix for impregnating carbon nanotubes (CNTs) to produce bacterial cellulose/carbon nanotubes (BC/CNTs) nanocomposite. The objective of this study was to investigate the crystal structure of BC/CNTs nanocomposite after acetylation treatment. Approximately 0.05 w/v% CNTs were added onto continuously developed BC. Then, the BC/CNTs nanocomposite was acetylated heterogeneously. RESULTS: The crystallinity characteristic of formed BC/CNTs acetate was analyzed using an X‐ray diffractometer (XRD). The crystallization index (CrI) of BC/CNTs acetate was better than BC acetate, i.e. 97:3 and 93:7, respectively. The crystallite size of BC microfibrils in BC/CNTs sheet was reduced because of the impregnated CNTs. However, the reduction of crystallite size for BC/CNTs acetate was lower than that of BC acetate showing that the existence of CNTs within BC micofibrils had protected the BC crystal structure from further destruction by acetylating agent. CONCLUSION: CNTs is a powerful substance that acted as a void filler between BC crystalline structure and protected the nano‐biocomposite from total degradation by the acetylation process. Copyright © 2011 Society of Chemical Industry     

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