Sorptional properties of carbon nanotubes produced from corn wastes

The sorption capacity of multiwalled nanotubes synthesized in the mechanical activation of amorphous carbon from corn wastes is investigated. The sorptional effectiveness of the nanotubes depends on their storage time. The use of carbon from corn waste as chelators is considered.     

Vacuum annealing of carbon nanotubes produced from amorphous carbon

In the vacuum annealing of carbon nanotubes formed by the mechanical activation of amorphous carbon (from sphagnum moss), the yield of purified nanotubes is 19–75 wt %. The potential of materials derived from sphagnum moss as enteric sorbents is considered.     

Modification of epoxy binder by carbon nanotubes obtained from vegetable raw materials

The formation of the multilayer nanotubes of a diameter from 10 up to 70 nm occurs as a result of mechanical activation of amorphous carbon obtained through pyrolysis of sphagnous moss at a temperature of 950°C. It has been established that modification of an epoxy binder by multilayer carbon nanotubes yields an improvement of the material mechanical properties and functioning parameters of the polymer composite system.     

Hydrogen storage in multilayer carbon nanotubes

Multilayer carbon nanotubes obtained by pyrolysis and mechanical activation of plant-derived amorphous carbon are excellent sorbents for hydrogen.     

Sorption properties of multilayer carbon nanotubes produced from cotton

The sorption capacity of multilayer carbon nanotubes that have been synthesized by the mechanical activation of amorphous carbon produced from cotton is investigated. The sorptional efficiency of the carbon nanotubes depends on the storage time. The use of carbon materials derived from cotton as chelators is considered.     

Processing of sphagnum moss to produce carbon nanotubes

Attention focuses on the processing of sphagnum moss and the sequence by which multiwalled carbon nanotubes are formed in the mechanical activation of amorphous carbon. Nanotube formation occurs within a mass of carbon particles.     

Kinetics of formation of multiwall nanotubes from moss

The technological aspects of the formation of nanofibrous carbon (multiwall nanotubes from 10 to 70 nm in diameter) in the process of the mechanical activation of amorphous carbon (1–27 h), which was obtained by the pyrolysis of sphagnum moss at a temperature of 950°C are considered. The sequence of the formation of a nanofiber structure and the change in the physicochemical characteristics of the formed nanotubes are presented. It is shown that the formation of nanotubes occurs in the bulk of carbon particles.     

Preparation and mechanical properties of natural rubber powder modified by carbon nanotubes

A suspension of carbon nanotubes in natural latex was obtained by liquid mixing and then was used to prepare powder natural rubber composites modified with carbon nanotubes by means of spray drying process. The composite powders were round‐like and fine, with an average diameter of less than about 5 μm. The dispersion of carbon nanotubes in the rubber matrix was improved remarkably compared with that obtained by the mechanical mixing method. By means of vulcanization tests, it was found that the addition of vulcanizing agent necessary for the powder rubber containing carbon nanotubes should be evidently greater than that in rubber prepared by mechanical mixing, there evidently existed vulcanization reversions for the natural rubber prepared by mechanical mixing, which disappeared in the powder rubber containing carbon nanotubes prepared by the spray drying process. The mechanical properties of the powder natural rubber containing carbon nanotubes were much improved because of the modification effect of carbon nanotubes in rubber. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4697–4702, 2006     

Exploitation of Carbon Nanotubes in High Performance Polyvinylidene Fluoride Matrix Composite: A Review

Among nanocarbon fillers, carbon nanotubes are considered to be an ideal reinforcement due to their miniscule size, and excellent electrical, thermal, and mechanical properties. However, carbon nanotubes can be utilized in polymer nanocomposites only if they are homogenously dispersed into polymer matrices. The multiwalled carbon nanotube has been concentrated as a reinforcement for an important type of thermoplastic polyvinylidene fluoride. This review initially focuses on carbon nanotubes modification both by mechanical methods and chemical functionalization to improve their dispersion. Moreover, the processing methods for polyvinylidene fluoride/carbon nanotubes nanocomposite have been discussed. Multiwalled carbon nanotubes facilitate the electrical conductivity, thermal, rheological, and mechanical properties of polyvinylidene fluoride.     

Oxidized multiwalled carbon nanotubes as effective reinforcement and thermal stability agents of poly(lactic acid) ligaments

In this study, nanocomposites of poly(lactic acid) (PLA) containing 0.5, 1, and 2.5 wt % oxidized multiwalled carbon nanotubes (MWCNT–COOHs) were prepared by the solved evaporation method. From transmission electron microscopy and scanning electron microscopy micrographs, we observed that the MWCNT–COOHs were well dispersed in the PLA matrix and, additionally, there was increased adhesion between PLA and the nanotubes. As a result, all of the studied nanocomposites exhibited higher mechanical properties than neat PLA; this indicated that the MWCNT–COOHs acted as efficient reinforcing agents, whereas in the nonoxidized multiwalled carbon nanotubes, the mechanical properties were reduced. Nanotubes can act as nucleating agents and, thereby, affect the thermal properties of PLA and, especially, the crystallization rate, which is faster than that of neat PLA. From the thermogravimetric data, we observed that the PLA/MWCNT–COOH nanocomposites presented relatively better thermostability than PLA; this was also verified from the calculation of activation energy. On the contrary, the addition of MWCNT–COOH had a negative effect on the enzymatic hydrolysis rate of PLA. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

碳纳米管填充PMI泡沫的制备及其吸波性能研究

将碳纳米管引入到PMI泡沫中,制备具有吸波性能的PMI泡沫,分析了碳纳米管对于PMI化学结构、泡孔结构以及力学性能的影响。结果表明,5%碳纳米管填充的PMI泡沫反射率能达到-15.23 dB,但碳纳米管的加入,会对PMI泡孔结构、力学性能造成不利影响。     

碳纳米管增强陶瓷基复合材料研究进展

鉴于其优良的力学性能、独特的物理和化学性能,碳纳米管被认为是最理想的增韧材料。本文主要从制备方法和力学性能两方面综述了碳纳米管增韧陶瓷基复合材料的研究现状,并针对研究中存在的问题,提出了相应的设想和发展趋势。     

Modification of carbon nanotubes and its effect on properties of carbon nanotube/epoxy nanocomposites

We have studied an effect of three types of modifications of carbon nanotubes (CNTs) on dispersion and mechanical properties of final epoxy‐amine based nanocomposites. First approach includes end‐walled covalent chemical modification at the ends of nanotubes. The second one is side‐walled covalent chemical modification along the whole length of nanotubes. The third procedure is noncovalent, physical modification done by the CNT surface coating with polyaniline. The modification of nanotubes was determined by X‐ray photoelectron spectroscopy. The prepared epoxy‐amine nanocomposites were characterized by dynamic‐mechanical analysis, tensile testing, light microscopy, transmission electron microscopy, and thermogravimetry. We observed an improvement of the mechanical properties and the thermal stability by addition of the carbon nanotubes to the epoxy matrix. The strong interactions between the nanotube and the polymer matrix were discovered in the nanocomposites with physically modified nanotubes. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Optimized process for the inclusion of carbon nanotubes in elastomers with improved thermal and mechanical properties

The effects of addition of reinforcing carbon nanotubes (CNTs) into hydrogenated nitrile–butadiene rubber (HNBR) matrix on the mechanical, dynamic viscoelastic, and permeability properties were studied in this investigation. Different techniques of incorporating nanotubes in HNBR were investigated in this research. The techniques considered were more suitable for industrial preparation of rubber composites. The nanotubes were modified with different surfactants and dispersion agents to improve the compatibility and adhesion of nanotubes on the HNBR matrix. The effects of the surface modification of the nanotubes on various properties were examined in detail. The amount of CNTs was varied from 2.5 to 10 phr in different formulations prepared to identify the optimum CNT levels. A detailed analysis was made to investigate the morphological structure and mechanical behavior at room temperature. The viscoelastic behavior of the nanotube filler elastomer was studied by dynamic mechanical thermal analysis (DMTA). Morphological analysis indicated a very good dispersion of the CNTs for a low nanotube loading of 3.5 phr. A significant improvement in the mechanical properties was observed with the addition of nanotubes. DMTA studies revealed an increase in the storage modulus and a reduction in the glass‐transition temperature after the incorporation of the nanotubes. Further, the HNBR/CNT nanocomposites were subjected to permeability studies. The studies showed a significant reduction in the permeability of nitrogen gas. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Impure carbon nanotubes as reinforcements for acrylated epoxidized soy oil composites

Stable dispersions of impure multiwall carbon nanotubes (multiwall carbon nanotubes and carbon soot) in an acrylated epoxidized soy oil (AESO) based thermosetting resin were obtained by mechanical stirring. The required stirring time increased with an increasing amount of carbon nanotubes. Thermogravimetric analysis of the polymerized samples showed some loss of multiwall carbon nanotubes due to sedimentation. The mechanical properties of the polymerized samples improved significantly (the modulus increased by 30%) for 0.28 wt % dispersed multiwall carbon nanotubes. Higher multiwall carbon nanotube loads resulted in significant aggregation during polymerization. The mechanical properties were compared with existing models for nanocomposites. Wide‐angle X‐ray scattering, optical microscopy, and transmission electron microscopy demonstrated the formation of aggregates at higher multiwall carbon nanotube loads, which reversed the potential for mechanical improvement. Because of the stability of the original dispersion, the aggregates were believed to form during polymerization. This aggregation was magnified by the carbon soot, so only small amounts of impure multiwall carbon nanotubes could be used as reinforcements. Transmission electron micrographs showed good adhesion of the polymer matrix to the nanotubes upon the rupture of the polymer matrix. AESO was believed to act as a solubilizing surfactant, in line with previously published results. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1325–1338, 2005     

机械混炼制备碳纳米管/天然橡胶复合材料特性分析

通过机械混炼方法将碳纳米管与天然橡胶复合，与炭黑补强样品相比，碳纳米管在橡胶中的混入速度快，功率消耗低，温升幅度小，混炼胶的硫化焦烧时间略有增加，硫化返原现象减轻，硫化剂用量应适当增加。加入碳纳米管后，橡胶DSC曲线中的结晶熔融峰面积减少，交联反应放热峰变宽。碳纳米管复合材料的回弹、压缩疲劳性能明显优于炭黑补强样品，耐老化性能较好，拉伸、撕裂性能水平有待提高。     

Effect of carbon nanotubes on the curing and thermomechanical behavior of epoxy/carbon nanotubes composites

The processing of carbon nanotube based nanocomposites is one of the fastest growing areas in materials research due to the potential of significantly changing material properties even at low carbon nanotube concentrations. The aim of our work is to study the curing and thermomechanical behavior of carbon nanotube/epoxy nanocomposites that are critical from an application standpoint. Multiwall carbon nanotubes–epoxy composites are prepared by solvent evaporation based on a commercially available epoxy system and functionalized multiwalled carbon nanotubes. Three weight ratio configurations are considered (0.1, 0.5, and 1.0 wt%) and compared to both the neat epoxy to investigate the nano‐enrichment effect. We focus here on the modification of the curing behavior of the epoxy polymer in the presence of carbon nanotubes. It has been observed that introducing the multiwall carbon nanotubes delays the polymerization process as revealed by the modification of the activation energy obtained by differential scanning calorimetry. The viscoelastic response of the nanocomposites was studied from the measurements of storage modulus and the loss factor using dynamic mechanical analysis to evaluate the effect of the interface in each matrix/carbon nanotube system with changing matrix mobility. These measurements provide indications about the increase in the storage modulus of the composites, shift in the glass transition temperature due to the restriction of polymer chain movement by carbon nanotubes. POLYM. COMPOS., 35:441–449, 2014. © 2013 Society of Plastics Engineers     

Computational investigation of the mechanical properties of nanomaterials

The mechanical responses of carbon nanotubes are examined using classical molecular dynamics simulations. Several different types of nanotubes are considered, including pristine single-walled tubes that are empty, filled with fullerenes to form peapods, filled with other nanotubes to form multi-walled tubes, or chemically functionalized. In addition, the responses of single-walled nanotubes with wall vacancies are considered. The results show how the bending force of filled nanotubes increases relative to the bending force of empty nanotubes and indicates how these increases come about. In addition, the simulations reveal the way in which the magnitude of these increases depend on the type of filling material and, in the case of multi-walled tubes, the number of inner tubes. These simulations further illustrate the way in which the inner nanotubes support higher external loads than the fullerenes in cases when the outer nanotubes are identical. The results also indicate that both the bending and buckling forces depend on temperature and the reasons for this dependence are discussed. Lastly, the simulations demonstrate the way in which the introduction of vacancy defects and covalently bound functional groups to the nanotube walls degrades the nanotubes' mechanical properties.     

镍纳米管的电化学组装与表征

以多孔阳极氧化铝（AAO）为模板，通过敏化和活化处理，再采用电化学方法沉积镍，组装成具有稳定结构的镍纳米管。透射电镜（TEM）分析表明，镍纳米管的管径在纳米范围内，长度最长可达微米。实验表明：适当的敏化和活化条件，以及电化学沉积镍时的电流和时间是影响镍纳米管生长的关键因素。     

Morphology,thermal stability,and dynamic mechanical properties of atactic polypropylene/carbon nanotube composites

Nanocomposites based on atactic polypropylene (aPP) and multiwall carbon nanotubes were prepared by melt blending at 80°C with a Barabender mixer. The morphology, thermal stability, and dynamic mechanical properties of the obtained composites were studied subsequently. SEM observations indicate that the nanotubes are well dispersed in the aPP matrix. Each nanotube is covered by a layer of aPP molecules. Thermal stability of the aPP in nitrogen is found to be enhanced significantly by the addition of nanotubes. Peak temperature of the DTG curve for the nanocomposite with 5 wt % nanotube loading shows about 70°C higher than that of pure aPP. Dynamic mechanical properties of aPP are also influenced by nanotubes, as shown by the increase in the storage modulus as well as significantly broadened loss tanδ peak. These effects of nanotubes on the thermal stability and mechanical properties of aPP are explained by the adsorption effect of the aPP molecules on the nanotube surfaces in this study. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1087–1091, 2005