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Enhancement of Elastic Modulus of Epoxy Resin with Carbon Nanotubes  [PDF]
Vijay Kumar Srivastava
World Journal of Nano Science and Engineering (WJNSE) , 2011, DOI: 10.4236/wjnse.2011.11001
Abstract: Nanocomposites consisting of multiwall carbon nanotubes (MWCNT) and epoxy resin were produced by a standard calendaring technique. In this study, 3% multiwall carbon nanotube particles were dispersed in epoxy resin by weight to produce the multiwall carbon nanotubes/epoxy composite. Nanohardness and Raman spectroscopy tests were used to obtain the modulus of elasticity and Raman intensity of MWCNTs/ epoxy resin composite. The results show that the Raman intensity increased with the increase of Raman shift and Raman intensity also affected with the reinforcement of multiwall carbon nanotubes and 1% exposure of laser power. Also, nanohardness increased with increase of modulus of elasticity, which indicated that the toughness of epoxy resin improved with the addition of multiwall carbon nanotubes.
Thermo-mechanical characterization of epoxy nanocomposites with different carbon nanotube distributions obtained by solvent aided and direct mixing.
M. Zarrelli,A. Martone,C. Formicola,F. Piscitelli
eXPRESS Polymer Letters , 2012, DOI: 10.3144/expresspolymlett.2012.56
Abstract: Two different routes, namely solvent aided dispersion and direct mixing, were employed to disperse Multi-Walled Carbon Nanotubes (MWNTs) into a mono-component epoxy system used as matrix for advanced composites. In the first route, MWCNTs were diluted in three different solvents (acetone, sodium dodecyl sulfate and ethanol) and then mixed with the matrix by tip sonication. In the second case, carbonaceous nanoparticles were added directly into the hosting system and dispersion was carried out by using three different techniques (mechanical stirring, magnetic agitation and tip sonication). The effects of the solvents and agitation energy were investigated by optical microscopy at micron level, in order assess the more efficient dispersion procedure for the considered epoxy system. It was demonstrated that parameters associated with direct mixing rather than solvent solubility govern MWCNT dispersion. Optical analysis of the nanocomposite morphology evidenced a very low density of MWCNTs micron sized aggregates in the case of direct mixed tip sonicated samples if compared to those obtained by solution aided dispersion. In addition, nanocomposites obtained by sonication showed the lowest density of MWCNTs micron sized aggregates, also when compared with mechanically and magnetically stirred system. Dynamic Mechanical Analysis (DMA) and Thermo-Mechanical Analysis (TMA) results confirm the final result that among the considered direct mixing techniques, the direct tip sonication represents the most efficient route for MWCNT dispersion. Moreover, the mixing temperature of the hosting matrix system represents a fundamental feature in enhancing the MWCNT de-bundling and dispersion. Small X-ray Scattering analysis revealed that a nanosized structure of nanotubes is formed in the case of the tip sonicated samples that is heuristically correlated with both the maximum enhancement of mechanical modulus and the maximum reduction of thermal expansion coefficients.
Carboxyl-terminated butadiene-acrylonitrile-toughened epoxy/carboxyl-modified carbon nanotube nanocomposites: Thermal and mechanical properties
H. F. Xie,Y. T. Wang,C. S. Wang,H. Y. Yin
eXPRESS Polymer Letters , 2012, DOI: 10.3144/expresspolymlett.2012.77
Abstract: Carboxyl-modified multi-walled carbon nanotubes (MWCNT–COOHs) as nanofillers were incorporated into diglycidyl ether of bisphenol A (DGEBA) toughened with carboxyl-terminated butadiene-acrylonitrile (CTBN). The carboxyl functional carbon nanotubes were characterized by Fourier-transform infrared spectroscopy and thermogravimetric analysis. Furthermore, cure kinetics, glass transition temperature (Tg), mechanical properties, thermal stability and morphology of DGEBA/CTBN/MWCNT–COOHs nanocomposites were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), universal test machine, thermogravimetric analysis and scanning electron microscopy (SEM). DSC kinetic studies showed that the addition of MWCNT–COOHs accelerated the curing reaction of the rubber-toughened epoxy resin. DMA results revealed that Tg of rubber-toughened epoxy nanocomposites lowered with MWCNT–COOH contents. The tensile strength, elongation at break, flexural strength and flexural modulus of DGEBA/CTBN/MWCNT-COOHs nanocomposites were increased at lower MWCNT-COOH concentration. A homogenous dispersion of nanocomposites at lower MWCNT–COOH concentration was observed by SEM.
Optimizing the Processing Conditions for the Reinforcement of Epoxy Resin by Multiwalled Carbon Nanotubes  [PDF]
S. Arun,Mrutyunjay Maharana,S. Kanagaraj
Journal of Nanotechnology , 2013, DOI: 10.1155/2013/634726
Abstract: The reinforcement of epoxy by MWCNTs is done to obtain the required properties of composites. However, the homogeneous dispersion of MWCNTs in epoxy is a critical problem. Hence, an attempt is made to optimize the processing conditions for dispersing the MWCNTs in epoxy by solvent dispersion technique. The epoxy/MWCNTs mixture was prepared using three methods: (1) magnetic stirring at 55°C, (2) hot air oven process at 55°C, and (3) vacuum oven process at room temperature. The nanocomposites having 0.1 and 0.2?wt.% of MWCNTs were prepared, for each method. The mechanical properties of nanocomposites were studied as per ASTM-D695, and the thermal conductivity was measured using KD2 probe. It is observed that the compressive strength, Young’s modulus, and thermal conductivity of 0.2?wt.% of MWCNTs prepared by vacuum oven method were found to be enhanced by 39.4, 10.7, and 59.2%, respectively, compared to those of pure epoxy. Though the properties of nanocomposites were increased with MWCNTs’ concentration irrespective of the processing techniques, the vacuum-processed sample showed the most enhanced properties compared to any other method. It is concluded that a unique method for the dispersion of MWCNTs in epoxy is the solvent dispersion technique with vacuum drying process. 1. Introduction The usage of nanoparticles as the reinforcement in a polymer matrix is increased enormously to achieve the required properties of composites. Among all the fillers such as TiO2, ZrO2, and nanoclay, multiwalled carbon nanotubes (MWCNTs) were paid a lot of attention because of their attractive mechanical properties which were reported by Gojny et al. [1]. Good aspect ratio of MWCNTs with the specific surface area of 1300?m2/g helps in effective stress transfer from the matrix, which was studied by Yu et al. [2]. The desirable properties of MWCNTs made them a candidate for reinforcing the polymer matrix. Kim et al. [3] found that the homogenous dispersion of the MWCNTs which gives good interaction between the matrix and the reinforcement must be ensured, in order to achieve the improved properties of epoxy/MWCNTs nanocomposites. Starkova et al. [4] also evaluated the mechanical properties of the epoxy-based composites. The enhancement of Young’s modulus of 0.1?wt.% composites was found to be 2% compared to that of pure epoxy. Mahfuz et al. [5] studied the influence of MWCNTs in epoxy, and it was found that the mechanical and thermal properties of the composites were increased. It was observed by He and Tjong [6] that the homogeneous dispersion of reinforcement was
Tribological Behavior of Multi-Walled Carbon Nanotube/Epoxy Resin Nanocomposites

WANG Shi-kai~,CHEN Xiao-hong~,SONG Huai-he~,LI Sheng-hua~,JIN Yuan-sheng~ hemical Reaction of Ministry of Education,Beijing University of Chemical Technology,Beijing,Chin,

摩擦学学报 , 2004,
Abstract: Carbon nanotubes (WMNTs)/epoxy resin nanocomposites were prepared making use of ultrasonic dispersion and casting molding. The influence of the MWNTs on the friction and wear behaviors of the resulting nanocomposites sliding against AISI-1045 steel was investigated on an Optimol-SRV tribotester at ambient condition. The worn surface morphologies of the composites were observed on a scanning electron microscope. It was found that the incorporation of the MWNTs contributed to greatly increase the friction-reducing and antiwear abilities of the WMNTs/EP composites. Moreover, the MWNTs/EP composite prepared in the presence of ultrasonic dispersion with a larger power had better friction-reducing and antiwear abilities than that prepared with the ultrasonic dispersion of a smaller power, which was attributed to the different dispersion uniformity of the WMNTs in the resin matrix thereat. The epoxy resin was dominated by adhesion fatigue peeling off and severe plastic deformation as it slid against the steel, while the adhesion and plastic deformation were considerably abated for the nanocomposites under the same test conditions, which was attributed to the strengthening and self-lubricating functions of the WMNTs.
Preparation, Characterization, and Modeling of Carbon Nanofiber/Epoxy Nanocomposites
Lan-Hui Sun,Zoubeida Ounaies,Xin-Lin Gao,Casey A. Whalen,Zhen-Guo Yang
Journal of Nanomaterials , 2011, DOI: 10.1155/2011/307589
Abstract: There is a lack of systematic investigations on both mechanical and electrical properties of carbon nanofiber (CNF)-reinforced epoxy matrix nanocomposites. In this paper, an in-depth study of both static and dynamic mechanical behaviors and electrical properties of CNF/epoxy nanocomposites with various contents of CNFs is provided. A modified Halpin-Tsai equation is used to evaluate the Young's modulus and storage modulus of the nanocomposites. The values of Young's modulus predicted using this method account for the effect of the CNF agglomeration and fit well with those obtained experimentally. The results show that the highest tensile strength is found in the epoxy nanocomposite with a 1.0 wt% CNFs. The alternate-current (AC) electrical properties of the CNF/epoxy nanocomposites exhibit a typical insulator-conductor transition. The conductivity increases by four orders of magnitude with the addition of 0.1 wt% (0.058 vol%) CNFs and by ten orders of magnitude for nanocomposites with CNF volume fractions higher than 1.0 wt% (0.578 vol%). The percolation threshold (i.e., the critical CNF volume fraction) is found to be at 0.057 vol%.
A Micro-Mechanical Model for Elastic Modulus of Multi-Walled Carbon Nanotube/Epoxy Resin Composites
International Journal of Composite Materials , 2012, DOI: 10.5923/j.cmaterials.20120202.01
Abstract: Multi-walled carbon nanotube (MWCNT) powder was used as reinforcement in epoxy resin with weight percentages 0.5, 1, 2 and 3% respectively. Dispersion of MWCNTs in the epoxy resin was obtained by a three mill rolling process. Tensile strength, compressive strength and elastic modulus were obtained from load versus displacement results. A theoretical model was developed to calculate the elastic modulus and compare with the experimental results. There was a similar trend in the experimentally obtained elastic modulus and in a modified Halpin-Tsai theory. Results show that the tensile strength, compressive strength and elastic modulus of epoxy resin are increased with the increasing of percentage of MWCNT fillers. The significant improvements in tensile strength, compressive strength and elastic modulus were attributed to the excellent dispersion of MWCNT filler in the epoxy resin.
Microstructure and Properties of Polypropylene/Carbon Nanotube Nanocomposites  [PDF]
Dimitrios Bikiaris
Materials , 2010, DOI: 10.3390/ma3042884
Abstract: In the last few years, great attention has been paid to the preparation of polypropylene (PP) nanocomposites using carbon nanotubes (CNTs) due to the tremendous enhancement of the mechanical, thermal, electrical, optical and structural properties of the pristine material. This is due to the unique combination of structural, mechanical, electrical, and thermal transport properties of CNTs. However, it is well-known that the properties of polymer-based nanocomposites strongly depend on the dispersion of nanofillers and almost all the discussed properties of PP/CNTs nanocomposites are strongly related to their microstructure. PP/CNTs nanocomposites were, mainly, prepared by melt mixing and in situ polymerization. Young’s modulus, tensile strength and storage modulus of the PP/CNTs nanocomposites can be increased with increasing CNTs content due to the reinforcement effect of CNTs inside the polymer matrix. However, above a certain CNTs content the mechanical properties are reduced due to the CNTs agglomeration. The microstructure of nanocomposites has been studied mainly by SEM and TEM techniques. Furthermore, it was found that CNTs can act as nucleating agents promoting the crystallization rates of PP and the addition of CNTs enhances all other physical properties of PP. The aim of this paper is to provide a comprehensive review of the existing literature related to PP/CNTs nanocomposite preparation methods and properties studies.
Carbon Nanotube-Reinforced Thermotropic Liquid Crystal Polymer Nanocomposites  [PDF]
Jun Young Kim
Materials , 2009, DOI: 10.3390/ma2041955
Abstract: This paper focuses on the fabrication via simple melt blending of thermotropic liquid crystal polyester (TLCP) nanocomposites reinforced with a very small quantity of modified carbon nanotube (CNT) and the unique effects of the modified CNT on the physical properties of the nanocomposites. The thermal, mechanical, and rheological properties of modified CNT-reinforced TLCP nanocomposites are highly dependent on the uniform dispersion of CNT and the interactions between the CNT and TLCP, which can be enhanced by chemical modification of the CNT, providing a design guide of CNTreinforced TLCP nanocomposites with great potential for industrial uses.
Effect of aging on the reinforcement efficiency of carbon nanotubes in epoxy matrix  [PDF]
A?ssa Allaoui,Pierre Evesque,Jinbo Bai
Physics , 2009, DOI: 10.1007/s10853-008-2728-5
Abstract: The reinforcement efficiency of carbon nanotubes (CNTs) in epoxy matrix was investigated in the elastic regime. Cyclic uniaxial tensile tests were performed at constant strain amplitude and increasing maximum strain. Post-curing of the epoxy and its composite at a temperature close to the glass transition temperature allowed us to explore the effect of aging on the reinforcement efficiency of CNT. It is found that the reinforcement efficiency is compatible with a mean field mixture rule of stress reinforcement by random inclusions. It also diminishes when the maximum strain increased and this effect is amplified by aging. The decrease of elastic modulus with increasing cyclic maximum strain is quite similar to the one observed for filled elastomers with increasing strain amplitude, a phenomenon often referred as the Payne effect.
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