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Mechanical and morphological characterization of polymer-carbon nanocomposites from functionalized carbon nanotubes
Abstract
Carbon nanotubes were functionalized with poly(vinyl alcohol) (PVA). The water-soluble PVA–functionalized carbon nanotubes were then embedded into PVA matrix via a wet-casting method, resulting in polymer–carbon nanocomposite films with homogeneous nanotube dispersion. Composites with pristine and functionalized nanotubes were tested in tension. It was found that the mechanical properties of these nanocomposite films were significantly improved compared to the neat polymer film. Functionalization allowed good distribution of the nanotubes in the matrix, leading to higher film strength. Scanning electron microscopy shows an apparent good wetting of the nanotubes by the PVA matrix. These results are supportive of good interfacial bonding between the functionalized carbon nanotubes and the hosting polymer matrix.
... The main raw materials in this research are carbon fiber in the form of woven and epoxy resin which are widely found in the market. The carbon fiber used is woven twill type HDC-522-3K, brand name AMP-07, Taiwan product [10], while the resin used is an epoxy resin type (Eposchan) which is formed from two mixtures, namely Epoxy EPR 174 and Hardener EPH 555 with a composition as recommended by the producer. Supporting materials needed include Acetone as thinner. ...
... Microstructure imaged from the SEM display video. From SEM can produce stereo-paired images, where the observed sample/specimen can be tilted or rotated [8][9][10]. Figure 3 shows the surface microstructure and cross-section of the carbon fiber composite. ...
Developed countries are currently developing unmanned aerial vehicles (UAV), and the ability to fly these aircraft is still limited, especially in terms of distance and length of the flight. This capability can be increased by various technological developments, one of which is reducing the weight of the aircraft body by using lightweight and strong materials. So that the aircraft becomes lighter and stronger so that can reach longer distances, the material can use a polymer composite formed from polymer resin with carbon fiber reinforcement. This polymer composite material has been used in several parts of commercial aircraft and has even been used in fighter aircraft.t. This study aims to determine how much influence the curing time and type of carbon fiber composite forming process have on the mechanical strength and to observe the microstructure of the carbon fiber bond with the resin in its formation. The results of the mechanical characterization by means of a tensile test with the ASTM 3039 standard showed that the difference in curing time had no significant effect on the mechanical strength, whereas the curing time of 2 hours showed the highest strength. The difference in the process of forming these composites shows that the mechanical strength of the composite formed by VARI (Vacuum Assisted Resin Infusion) shows a high value, which is around 501 MPa, while the carbon fiber composite formed by the manual method, hand layup has a strength of only up to 288 MPa. From the observation of the microstructure of the carbon fiber composites, it can be seen that the carbon fiber composites formed by the VARI method have very good, compact, uniform, and non-porous surfaces.
... They attributed the results to the relatively large BC particles' size (250 µm) and distribution. Regarding nanosized materials, Paiva et al. [35] also reported a 4.8% decrease in strength when using nanosized carbon tubes (2.5 wt%) for reinforcing PVA composites. In this research, they attributed the reduction in strength to the tendency of the nanoparticles to agglomerate, preventing the uniform dispersion within the matrix. ...
... The effect of BC additive on thermal transitions of PLA and hemp-PLA composites was evaluated using DSC analysis. The first heating cycle is performed to eliminate the thermal history of the polymeric material [35]. As such, data retrieved from the second heating cycle were considered for discussion. ...
The present study investigated the effect of biochar (BC) addition on mechanical, thermal, and water resistance properties of PLA and hemp-PLA-based composites. BC was combined with variable concentration to PLA (5 wt%, 10 wt%, and 20 wt%) and hemp (30 wt%)-PLA (5 wt% and 10 wt%); then, composites were blended and injection molded. Samples were characterized by color measurements, tensile tests, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and water contact angle analysis. Experimental results showed that adding 5 wt% of BC enhanced the composite’s tensile modulus of elasticity and strength. Hence, the use of optimized loading of BC improved the mechanical strength of the composites. However, after BC addition, thermal stability slightly decreased compared with that of neat PLA due to the catalytic effect of BC particles. Moreover, the water-repelling ability decreased as BC content increased due to the specific hydrophilic characteristics of the BC used and its great porosity.
... Three-point bending tests carried out on nanocomposites are reported in Figures 9 and 10. As reported in the literature [12,20,22,38], the mechanical properties are very sensitive to the dispersion state. Thus, a poor CNT dispersion state (DD = 4.9) leads to a decrease of more than 20% for the Young's modulus, whereas the best dispersion state (DD = 74.5) ...
... The decrease of mechanical properties of nanocomposites compared to the neat network ones can be directly linked to the non-polymerized DGEBA prepolymer confined in the CNT agglomerates and/or to non-stoichiometric zones, as reported previously from reaction kinetics analyses. This reinforcing effect of CNT can be explained by the "crack-front pinning" process at the crack tip [38]. In such a process, the crack-front length increases as the crack meets rigid inclusions. ...
Carbon nanotube (CNT)-reinforced nanocomposites represent a unique opportunity in terms of designing advanced materials with mechanical reinforcement and improvements in the electrical and thermal conductivities. However, the toxic effects of these composites on human health have been studied, and very soon, some regulations on CNTs and on composites based on CNTs will be enacted. That is why the release of CNTs during the nanocomposite lifecycle must be controlled. As the releasing depends on the interfacial strength that is stronger between CNTs and polymers compared to CNTs in a CNT agglomerate, two dispersion states—one poorly dispersed versus another well dispersed—are generated and finely described. So, the main aim of this study is to check if the CNT dispersion state has an influence on the CNT releasing potential in the nanocomposite. To well tailor and characterize the CNT dispersion state in the polymer matrix, electronic microscopies (SEM and TEM) and also rheological analysis are carried out to identify whether CNTs are isolated, in bundles, or in agglomerates. When the dispersion state is known and controlled, its influence on the polymerization kinetic and on mechanical properties is discussed. It appears clearly that in the case of a good dispersion state, strong interfaces are generated, linking the isolated nanotubes with the polymer, whereas the CNT cohesion in an agglomerate seems much more weak, and it does not provide any improvement to the polymer matrix. Raman spectroscopy is relevant to analyze the interfacial properties and allows the relationship with the releasing ability of nanocomposites; i.e., CNTs poorly dispersed in the matrix are more readily released when compared to well-dispersed nanocomposites. The tribological tests confirm from released particles granulometry and observations that a CNT dispersion state sufficiently achieved in the nanocomposite avoids single CNT releasing under those solicitations.
... All these sectors benefit from PVA's unique properties, including excellent film formation, resistance to organic solvents, gas barrier properties, especially to oxygen, adhesive properties, biocompatibility, and to some extent, biodegradability (Chiellini et al., 2003). PVAbased composites have been developed in the past using various fillers like inorganic oxides (Yang, 2007;Dodda et al., 2015), clays (Strawhecker and Manias, 2000;Podsiadlo et al., 2007;Sapalidis et al., 2012), CNTs (Shaffer and Windle, 1999;Paiva et al., 2004;Ciambelli et al., 2005;Liu et al., 2005;Bhattacharya et al., 2006;Miaudet et al., 2007;Minus et al., 2010;Surdo et al., 2011;Li et al., 2013), graphene oxide (Salavagione et al., 2009a;Zhao et al., 2010;Swati et al., 2015;Ma et al., 2016), reduced graphene oxide (Salavagione et al., 2009b;Pourjavadi et al., 2015;Manna et al., 2016), or biomaterials (Sapalidis et al., 2007), all targeting to significantly improve the mechanical and thermal stability along with gas permeability, while trying to preserve the excellent optical transparency of PVA. As mentioned previously, the key parameter for successful preparation of polymer nanocomposites is the effective filler dispersion. ...
... Shaffer and Windle fabricated a series of PVA/CNTs nanocomposites (10-60%), and measured the thermomechanical and electrical properties of the developed films (Shaffer and Windle, 1999). Paiva et al. (2004) prepared functionalized CNTs/PVA composites, with nanotubes well dispersed into the PVA matrix affording films with higher strength compared to parent PVA films. Liu et al. (2005) prepared PVA films with functionalized SWCNTs with excellent optical transparency due to enhanced CNTs-polymer interactions. ...
A series of poly(vinyl alcohol) (PVA) nanocomposite films containing quaternized hyperbranched polyethyleneimine (PEI) functionalized multi-walled carbon nanotubes (ox-CNTs@QPEI) are prepared by solvent casting technique. The modified carbon-based material exhibits high aqueous solubility, due to the hydrophilic character of the functionalized hyperbranched dendritic polymer. The quaternized PEI successfully wraps around nanotube walls as polycations provide electrostatic repulsion. Various contents of ox-CNTs@QPEI ranging from 0.05 to 1.0% w/w were employed to prepare functionalized PVA nanocomposites. The developed films exhibit adequate optical transparency, improved mechanical properties and extremely high antibacterial behavior due to the excellent dispersion of the functionalized CNTs into the PVA matrix.
... To improve the interfacial interaction, chemical modification of the filler surface is usually required. Presently, most research on polymer composites focuses on the effects of interfacial interactions on the improvement of mechanical properties [3][4][5], flame retardant properties [6][7][8], thermal conductivities [9,10], and electrical conductivities [11,12] while ignoring the impact on the material stability. Allen et al. reviewed the aging behavior of filled polymers and suggested that the matrix/filler interface plays an important role in the aging of these materials [13]. ...
The nature of the functional groups on the filler surface is one of the key influences on the interfacial interaction in the aging of polymer composites. However, the characteristics of this interfacial effect and its relation with functional groups remain unclear. In this study, we investigated the effects of interfacial interactions on the photooxidative aging of silica-filled polypropylene (PP) composites in which the interfaces comprise functional groups possessing different photooxidative properties. Results showed that the effects of interfacial interactions on the photooxidative aging of the silica-filled PP composites were closely related to the composition of the interfacial functional groups. Since the effect of interfacial interactions on the PP oxidation rate was correlated with the concentration of the interfacial functional groups, an aging kinetic model of interfacial effects could be constructed for determining the role of interfacial functional groups in the photooxidative aging of PP composites. This study will provide new ideas for developing interfacial antioxidant strategies for polymer composites.
... Nanostructured semiconductors have a great interest due to their unique physicochemical properties, which are different than their bulk [1][2][3]. In recent years ZnO, a multifunctional material, has attracted attention of many researchers due to their interesting properties suitable for optoelectronics and electrical applications such as, ultraviolet lasers devices, thin-film transistor, light-emitting diodes, solar cells, biological sensors [4,5]. ...
... Electrical conductivity varies with the concentration of the conductive component, and it has been reported that it can be made more or less dependent on the strain to fabricate strain sensors with different sensitivities [7,10,11]. Many computational and experimental techniques have been used to study these composites, ranging from numerical simulations to several experimental techniques, the most widely used being scanning electron microscopy (SEM) [12][13][14] for a surface analysis and confocal Raman microscopy measurements [15][16][17][18] for a bulk analysis. The fabrication procedures and subsequent processing have also been reported to significantly affect the composite electromechanical properties [19]. ...
The increasing interest in stretchable conductive composite materials, that can be versatile and suitable for wide-ranging application, has sparked a growing demand for studies of scalable fabrication techniques and specifically tailored geometries. Thanks to the combination of the conductivity and robustness of carbon nanotube (CNT) materials with the viscoelastic properties of polymer films, in particular their stretchability, “surface composites” made of a CNT on polymeric films are a promising way to obtain a low-cost, conductive, elastic, moldable, and patternable material. The use of polymers selected for specific applications, however, requires targeted studies to deeply understand the interface interactions between a CNT and the surface of such polymer films, and in particular the stability and durability of a CNT grafting onto the polymer itself. Here, we present an investigation of the interface properties for a selected group of polymer film substrates with different viscoelastic properties by means of a series of different and complementary experimental techniques. Specifically, we studied the interaction of a single-wall carbon nanotube (SWCNT) deposited on two couples of different polymeric substrates, each one chosen as representative of thermoplastic polymers (i.e., low-density polyethylene (LDPE) and polypropylene (PP)) and thermosetting elastomers (i.e., polyisoprene (PI) and polydimethylsiloxane (PDMS)), respectively. Our results demonstrate that the characteristics of the interface significantly differ for the two classes of polymers with a deeper penetration (up to about 100 μm) into the polymer bulk for the thermosetting substrates. Consequently, the resistance per unit length varies in different ranges, from 1–10 kΩ/cm for typical thermoplastic composite devices (30 μm thick and 2 mm wide) to 0.5–3 MΩ/cm for typical thermosetting elastomer devices (150 μm thick and 2 mm wide). For these reasons, the composites show the different mechanical and electrical responses, therefore suggesting different areas of application of the devices based on such materials.
... In light of this, it has been observed that some polymer/CNT nanocomposites have tensile strengths between 0.1 and 5 GPa and Young's moduli between 5 and 200 GPa [76]. Using CNTs as reinforcement generally improved the mechanical properties of some polymers, including epoxy [77][78][79][80], polystyrene (PS) [81], polyethylene [82,83], PMMA [84,85], poly (pphenylene benzobisoxazole) (PBO) [86], polyvinyl alcohol (PVA) [87], polyester elastomers (PEE) [88], polycarbonate (PC) [89], polyamide-6 [90], To prevent agglomerations or bundles that adversely influence the mechanical properties of PMNCs, typically when CNTs content exceeds 2-3%, the optimal CNT loading must be carefully examined [92]. The detrimental impact on the tensile strength of nanocomposite is specifically caused by the inadequate interfacial interaction between CNT and polyester [93,94,95,96,97]. ...
Due to the anisotropic, heterogeneous structure, and advanced mechanical properties of these materials combined with the size effects in micromachining, micromachining of nanocomposites is thought to be a challenging operation. In terms of high cutting force, poor surface quality, and rapid tool wear, it results in worse machinability. The first of these two parts of this review paper will provide a thorough overview of the mechanical characteristics of diverse nanocomposites, while the second part will concentrate on the micro-machinability of these nanocomposite materials.
... At specified NPs volume fractions, the smaller NPs have a larger interfacial area, resulting in a large area of stress transfer regions (Lau et al. 2004). Strength also influences the efficiency of load transfer (Paiva et al. 2004). In contrast to composites with strong interfacial interaction (Thostenson and Chou 2002), composites with poorly adherent NPs would have insufficient strength due to noncontinuity produced by interfacial de-bonding, which inhibits the NPs from effectively transferring the applied load. ...
The development of natural fiber (NFr) composites for a variety of applications is on the rise. The optimization of the interfacial bonding (IFB) between the reinforcing NFr and polymer matrix is perhaps the single most critical aspect in the development of natural fibre polymer composites (NFPCs) with high mechanical performance. While the IFB is critical in determining the mechanical properties of the NFPCs, such as stress transfer, it is one of the least understood components. This article offers a summary of IFB mechanisms, different modification approaches targeted at lowering incompatibility and improving IFB, and evaluation of the impact of IFB. It has been found that 1) In general, interdiffusion, electrostatic adhesion, chemical reactions, and mechanical interlocking are accountable for the IFB; 2) the incompatibility of the fibre and matrix, which results in poor dispersion of the fiber, weak IFB, and ultimately worse composite quality, may be addressed through strategic modifications; and 3) Interfacial interactions between polymers and nanoparticles (NPs) are significantly improving their performance in areas like thermal, mechanical, robust IFB, and moisture absorption. As a result, this review study could be an important resource for scholars interested in coating and treating NFr to further enhance their surface characteristics.
... At specified NPs volume fractions, the smaller NPs have a larger interfacial area, resulting in a large area of stress transfer regions (Lau et al. 2004). Strength also influences the efficiency of load transfer (Paiva et al. 2004). In contrast to composites with strong interfacial interaction (Thostenson and Chou 2002), composites with poorly adherent NPs would have insufficient strength due to noncontinuity produced by interfacial de-bonding, which inhibits the NPs from effectively transferring the applied load. ...
Due to growing environmental consciousness and the depletion of oil supplies, numerous efforts have been made to replace synthetic fibers in fiber-reinforced composites with natural fibers (NFr). The low cost and abundance of NFr and its biodegradability and low density have encouraged researchers worldwide to study their potential applications in several industrial sectors. However, NFr has several disadvantages: excessive moisture absorption and subsequent swelling and degradation, low chemical and fire resistance, and insufficient interfacial interactions with polymers. Consequently, there is great interest in modifying the surface of NFr using a variety of methods. This chapter presents an overview of the NFr, its characterization, the problems associated with adding NFr to polymer composites. This literature survey suggests an in-depth review of photocatalysis by utilizing photocatalysts nanoparticle (PHNPs) aimed at increasing the hydrophobicity and interfacial bonding between the NFr and the matrix Using a photo-induced oxidation mechanism to disassemble water molecules, pollutants, and bacteria in a wet environment. Additionally, we reviewed the effects of these PHNPs on the moisture absorption, mechanical characteristics, and dimensional stability of NFr composites. As a result, this review article may make a valuable contribution to researchers interested in coating and treating NFr to further enhance their surface characteristics.
... This implies there is a long way to go with cellulose fibers to replace glass fibers. However, cellulose can be processed to reinforce PP for some b Fig. 13 a Comparing neat materials with cellulose nanomaterials (CN), CNT and PVOH composites, b The plot near the origin (Kunugi et al. 1990;Vigolo et al. 2000;Dalton et al. 2003;Zhang et al. 2003Zhang et al. , 2004Paiva et al. 2004;Chen et al. 2005Chen et al. , 2018Liu et al. 2005Liu et al. , 2018Bhattacharyya et al. 2006;Xu et al. 2010;Di et al. 2012;Mercader et al. 2012;Uddin et al. 2012;Behabtu et al. 2013;Koga et al. 2013;Salajkova et al. 2013;Hamedi et al. 2014;Lu et al. 2014;Wei et al. 2015;Yee et al. 2018) Fig. 14 Fiber-reinforced polypropylene (PP) composites. GFglass fiber, CNT-carbon nanotubes, RC-regenerated cellulose fiber, WF-wood flour, CN-cellulose nanomaterials (Belgacem et al. 1994;Cantero et al. 2003;Nunez et al. 2003;Qiu et al. 2003;Xia et al. 2004;Manchado et al. 2005;Borja et al. 2006;McIntosh et al. 2006McIntosh et al. , 2007Cheng et al. 2007;Zhao et al. 2007;Johnson et al. 2008;Masuda and Torkelson 2008;Prashantha et al. 2009;Yang and Gardner 2011;Huque et al. 2012;Suzuki et al. 2013Suzuki et al. , 2014Cao et al. 2014;Iwamoto et al. 2014b;Khoshkava and Kamal 2014;Unterweger et al. 2014;Matuana and Stark 2015;Peng et al. 2016;Franciszczak et al. 2017;Risnasari et al. 2018;Wang et al. 2018;Kim et al. 2019b;Mihalic et al. 2019) applications, which do not require the high performance achieved with glass fibers, rather only higher than neat PP. ...
The current materials predominately come from fossil feedstocks and minerals. The pressures from climate change and plastic pollution challenge us to develop a bioeconomy, replacing petroleum-based products with bio-based and biodegradable products. Cellulose emerges as a versatile biopolymer to make hydrogels for absorbents, aerogels for insulation, membranes for filters, films for packaging, and fibers for textiles and reinforcements. Wood-based cellulose is increasingly perceived by relevant stakeholders to be renewable, biodegradable, and sustainable. Can the properties of cellulose-based materials compete with conventional synthetic materials? Knowledge and discoveries concerning cellulose properties and applications are scattered throughout the scientific literature base. This paper surveys the mechanical properties of cellulose-based materials in the literature using tensile properties as indicators and visualizes the data compared with other competitive materials. The goal is to provide insights into the potential and challenges of using cellulose-based products to replace synthetic materials for a sustainable society.
Graphic abstract
... Tensile strength and Young's modulus of the resulting new material have demonstrated an improvement as high as 34% and 60%, respectively [6]. The results obtained by Paiva et al. [7] showed that Young's modulus of SWNT/poly(vinyl alcohol) (PVA) composite has improved by 55% when only 5 wt% of functionalized SWNTs has been used to fabricate the composite. Also, an increase in the tensile modulus of more than 130% for MWNTs/PVA composites at values as low as 2 wt% nanotube loading has been reported [8]. ...
A better understanding of the bonding and aggregation processes occurring between carbon nanomaterials and metal oxide particles in aqueous solutions is important in the development of novel nanosolids for applications in the areas of sensor development, highly conductive paint, nanotube alignment, polymer composites, Li-ion batteries, and many other areas. The current investigation reviews these processes and presents a detailed description of the aggregation processes occurring between carbon nanomaterials and metal oxide particles (metals) in various aqueous solutions. The results indicate that the charge attraction between the particles results in a strong homogeneous bonding that occurs within the aqueous solution and for the first time demonstrate and describe the aggregation process of these nanoparticles. The relative importance of many parameters that impact the aggregation process is identified and discussed, and guidelines for controlling the aggregation process are presented. This is a simple and cost-effective process to manufacture a novel nano-solid based on carbon nano-material and metal oxide. In addition, the process is easy to scale up and optimize. The methodology could lead to many significant applications as well as commercialization.
... The smaller nanoparticles possesses larger interfacial area at a specific nanofillers volume-fractions, resulting in high area of stress transfering regions [162]. The effectiveness of load transferring is also function of the strength [163]. Unlike composites with high interfacial interaction [164], poor strength will suffice for composites with poorly adhered fillers ascribed to non-continuity due to interfacial de-bonding hindering the nanofiller from effectively transfering the applied load. ...
Polymer nanocomposites (PNCs), and plant fiber reinforced polymer biocomposites (GBCs), and nano-biocomposites (GPNCs) are versatily applied in various industrial, automotive, aerospace, marine, and oil and gas sectors because of their design flexibility and vast range of properties. Researches have shown that composites behavior are highly dependant on the properties of its constituting components. However, numerious experimental and simulative studies have demonstrated that composite characteristics does not necessarily align with the rule of mixtures. This trend implies that other factors exist which influence the overall composites physicochemical behavior apart from properties of the constituting components. Polymer matrices/nanofillers interfacial interactions is a major parameter highly affecting nanocomposite behavior. Thus, this paper elucidates various interactions between PNCs components, aspects of polymer/fiber interface in GBCs, and GPNCs, their modes of enhancements, methods of measuring various interactions, and influence of interfacial interactions on selected properties of PNCs, GPNCs, and GBCs.
... The SEM images of the fractured surfaces of the PVA/SF-SWNT composites were shown in figure 3. The crosssection of the nanocomposites looked smooth, and no residual structure of SWNT was observed for the nanocomposite. Similar morphological behavior was also observed for PVA based carbon nanotube composite film and can be attributed to the strong interfacial interactions between SWNT and the PVA matrix [30,31]. Additionally, the roughness of the nanocomposite increases with the concentration of SWNT. ...
Polyvinyl alcohol/surfactant-free single-walled carbon nanotube (PVA/SF-SWNT) nanocomposites were synthesized by a facile solution-cast technique. The effect of SF-SWNT on the structural, surface-morphological, mechanical, electrical, and electrochemical properties of the nanocomposite was studied. The surface morphology and Fourier Transform Infrared Spectroscopy demonstrate an increased degree of interaction between PVA and SF-SWNT resulting in improved mechanical strength of the nanocomposite. Incorporation of SF-SWNT was found to improve the DC electrical conductivity by almost five orders of magnitude. Furthermore, the effect of SWNT on the electrochemical properties of the nanocomposite was also studied. The PVA/SF-SWNT composite exhibits specific capacitance as high as 26.4 F g ⁻¹ at a current density 0.5 mA g ⁻¹ , which is four times higher than that of PVA (6.1 F g ⁻¹ ). The impedance spectroscopy analysis reveals that the incorporation of SWNT reduces the charge transfer resistance of the nanocomposites resulting in better capacitive performance.
... Dans le but d'élaborer des biocapteurs reproductibles, le polymère doit être réparti de façon homogène à la surface de l'électrode (autant sur les plots, que sur leurs pointes, et entre eux). La microscopie électronique à balayage permet d'accéder à ce genre d'informations [303][304][305] . ...
Cette thèse explore deux voies d’amélioration des performances d'un biocapteur électrochimique d'affinité pour la détection des anticorps anti-NS1 de la dengue.La première volonté est l'amélioration de la limite de détection et de la sensibilité des biocapteurs par microstructuration du transducteur. Une modélisation basée sur les éléments finis a permis de définir la gamme optimale des paramètres géométriques des microplots. Après construction, les électrodes recouvertes de microplots ont été caractérisées par voltampérométrie cyclique et par microscopie électronique à balayage. A l'issue de l'optimisation, des biocapteurs à glucose ont été construits afin de démontrer l'accroissement des performances d’un biocapteur ampérométrique. Enfin, dans le but de valider l'intérêt des microplots pour un biocapteur d'affinité, un modèle d'immunocapteur impédance métrique sans marquage permettant la quantification de l'anticorps de la sous-unité B de la toxine du choléra est étudié avant de procéder à la réalisation d'un immunocapteur d'intérêt pour l'anticorps de la dengue. Ils sont réalisés sur deux types d'électrodes : les électrodes recouvertes de microplots et des électrodes interdigitées.La seconde volonté est l'amélioration de la longévité du stockage des biocapteurs à flux latéral par microencapsulation des biomolécules marquées, nécessaires à la détection par compétition. Pour cela, des microcapsules de polymère, fabriquées à faible coût, sont développées. Le bleu de méthylène et l'enzyme glucose oxydase ont été encapsulées sous forme sèche. Leur relargage a été suivi par spectrophotométrie UV-Visible et/ou par électrochimie après cassure des microcapsules par action mécanique et/ou par ultrasons.
... Dans le but d'élaborer des biocapteurs reproductibles, le polymère doit être réparti de façon homogène à la surface de l'électrode (autant sur les plots, que sur leurs pointes, et entre eux). La microscopie électronique à balayage permet d'accéder à ce genre d'informations [303][304][305] . ...
This thesis explores two ways to enhance the performance of an electrochemical affinity biosensor for the detection of dengue anti-NS1 antibodies.
The first goal was to improve the limit of detection and sensitivity of biosensors using microstructuration of the transducer. Based on finite element modelling, an optimal range of the microcone geometric parameters was defined. After construction, the microcone-covered electrodes were characterised using cyclic voltammetry and scanning electron microscopy. At the end of the optimisation process, glucose biosensors were fabricated to demonstrate the increased performance gains of an amperometric biosensing platform. Finally, in order to validate the interest of the microcones for an affinity biosensor, a label-free impedimetric immunosensor allowing the quantification of the cholera toxin B-subunit was studied as a model before performing an immunosensor of interest for dengue antibodies. The immunosensors were made on two types of electrodes: microcone-coated electrodes and interdigitated electrodes.
A second goal was to improve the shelf-life of lateral-flow biosensors by microencapsulating labelled biomolecules, mandatory for competitive detection. For this purpose, low-cost polymer microcapsules have been developed. Methylene blue and an enzyme, glucose oxidase, were encapsulated in a dry state. Their release was followed by UV-visible spectroscopy and/or electrochemistry after breaking the microcapsules by mechanical action and/or with ultrasonic agitation.
... CNT to PLA increased its modulus and hardness by 4.6% and 10%, respectively. This enhancement in mechanical properties is attributed to the reinforcing effect of CNTs that has been widely reported for polymeric materials [46][47][48]. ...
To understand the interrelationship between the microstructure and degradation behavior of poly(lactic acid) (PLA), single-walled carbon nanotubes (CNTs) were introduced into PLA as nucleating agents. The degradation behavior of PLA-CNT nanocomposites was examined under accelerated weathering conditions with exposure to UV light, heat, and moisture. The degradation mechanism proceeded via the Norrish type II mechanism of carbonyl polyester. Differential scanning calorimetry (DSC) studies showed an increase in glass transition temperature, melting temperature, and crystallinity as a result of the degradation. However, pure PLA showed higher degradation as evidenced by increased crystallinity, lower onset decomposition temperature, embrittlement, and a higher number of micro-voids which became broader and deeper during degradation. In the PLA-CNT nanocomposites, CNTs created a tortuous pathway which inhibits the penetration of water molecules deeper into the polymer matrix, making PLA thermally stable by increasing the initial temperature of mass loss. CNTs appear to retard PLA degradation by impeding mass transfer. Our study will facilitate designing environmentally friendly packaging materials that display greater resistance to degradation in the presence of moisture and UV light.
... Porosity affects the mechanical properties of cement composites as well as the durability, where large size of pores reduces the mechanical properties and durability [38]. Porosity and pores size decrease with addition of CNTs into cement composites [39]. The small size of CNTs which is measured in Nano has ability to fill the pores hence decrease the porosity of cement composites. ...
Throughout the construction life, nanoparticles can change and modify the properties and functions of cement-based materials. The traditional cement materials have weak sustainability characteristics insufficient to develop high quality performance structures. Besides that, modifications of compressive and tensile strength and durability durations of cement composites are required. Consequently, a suitable range of Carbon nanotubes (CNTs) concentrations were applied to improve these certain properties. This review presents analysis of the earlier techniques of adding CNTs to cement composites and its influence to mechanical properties and durability. The detailed interactions of CNTs with cement composites, dispersion of CNTs, durability and mechanical performance measurements are addressed from several researches. CNTs addition contributes in adjustment of cement composite microstructures, hence improving the functional components and mechanical properties. If a proper dispersion of CNTs achieved, hydrate products of cement including C-S-H and Ca(OH)2 interact with active CNTs, resulting in decrement of porosity of Portland cement composites which filled up by CNTs proportions leading to increase the mechanical strength. Therefore, this paper present state of the art regarding applications of the additive CNTs in cement composite, the reviewing results of CNTs-cements shows a positive influence on mechanical strength and durability.
... In order to fabricate nanocomposites, inorganic materials are used as nanofillers to improve the properties of polymers [7,8]. Carbon nanotubes (CNTs) can be used as filler due to their nano size, high aspect ratio and most importantly, their high mechanical strength, electrical and thermal conductivity [9,10]. ...
In this study, surfactant dispersed MWCNTs were introduced as nanofillers into poly (vinyl) alcohol (PVA) and Chitosan (Cs) blend (ratio 50:50 wt%, optimized) by solution casting method to fabricate PVA/Cs/MWCNTs nanocomposite films. These nanocomposites were subjected to different characterization to study the variation of properties with different amount of MWCNTs loading. Various techniques, such as Optical microscopy (OM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA, DTGA), differential scanning calorimetry (DSC), impedance analyzer (IA), scanning electron microscopy (SEM) and universal testing machine (UTM) were used to study the physicochemical, morphological, electrical and thermo-mechanical properties of the nanocomposite films. The experimental results of FTIR illustrated that strong interaction among MWCNTs, Cs and PVA facilitated the crystallization of PVA and prevented the agglomeration of MWCNTs in the composite film. Tensile strength of the nanocomposite containing 1 wt% MWCNTs increased by 61.51% and elongation at break decreased by 20.07% in comparison to that of pure PVA/Cs blend film. Similarly, the conductivity of the nanocomposite containing 1 wt% MWCNTs was highest at 40V with the value of 1.99 x 103 S/cm.
... In addition to the methods to inhibit or encourage this transformation, have not been examined thoroughly to date the presence of either or both of these phases influence the optical properties' modification of the material. TiO 2 /PVA nanocomposites have acquired significant consideration for many applications, for instance, environmentally safe products [22], membrane separation, biodegradation applications [23], and Laser attenuation applications [24]. The present work aims to synthesize Anatase and Rutile TiO 2 nanoparticle phases using the sol-gel method by controlling only the calcination temperature as an easy and novel technique for the TiO 2 Anatase to Rutile transformation. ...
TiO2/PVA nanocomposites film was assembled using a solution casting technique, whereas the synthesis of TiO2 nanoparticles was achieved by the Sol-gel method. The control in TiO2 phases nanoparticle from Anatase, mix, and Rutile was taken place only by controlling the time and temperature of the calcination process, which belief as a new technique for that purpose. TiO2 nanoparticles with different phases employed as a filler and PVA as a host matrix. The established of TiO2 with different phases were examined by X-ray diffraction (XRD). At the same time, the shape and the approximate crystal size carried out by Transmission electron microscope (TEM), the XRD reveals the existence of anatase, rutile and mixed TiO2 phases with average crystal size (D) of 7 nm 78 nm and 42 nm for anatase, rutile, and mix phases, respectively. TEM of TiO2 nanoparticles indicates the spherical shape of the rutile phase, and the tetragonal shape appears clearly in anatase, and the impact of the calcination process on crystal size was considerable. The grain size noted in the TEM image has a good agreement with the XRD results estimated by applying Scherrer's equation. The optical properties of TiO2/ PVA composite films have been examined. The red-shifted of the direct optical band gap is achieved from 3.25 to 2.63 eV for phase transformation from anatase to rutile. The refractive index (n) dispersion was analyzed by applied the Wemple– Didomenico single oscillator model, and the dispersion parameters (Eo and Ed) were determined. Besides the photo-stability investigation of TiO2/PVA nanocomposite with the anatase phase of TiO2, which considers the characteristic phase.
... [61] Additionally, polymer/CNT nanocomposites can be prepared by different methods such as solution mixing, [62] melt mixing, [63] and wet-casting method. [64] Functionalization is an important aspect in producing smart polymer composites, which in turn forms a crucial interfacial interaction between CNT and the polymer matrix. Polystyrene for example has p stacking interaction between the CNTs and the aromatic rings, [65] in its CNT nanocomposite. ...
Oil sorbent membranes are highly effective materials in combating oil spills. Recent technological advancements in membrane preparations permit higher oil-sorption efficiency and easier oil recoverability. This review article discusses the main structural difference between the most commonly fabricated membranes. Next, it highlights the different membrane production methods and their role in producing effective membranes, while focusing on the recent advances in elevating the properties of the membranes through the addition of different nanocomposites. Consequently, the hydrophobic/hydrophilic properties are highlighted, which are critical in the oil-collection mechanism. Finally, it examines prediction and challenges with regards to oil/water separation and recovery. These concepts are discussed with emphasis on modern production methods and oil-sorption proficiency.
... There is evidence that incorporation of carbon nanotubes into the polymer increases ductility. However, some reports also represent the requirement of using uniform dispersion of nanofillers for the enhancement of properties (Meng et al. 2010;Paiva et al. 2004 andYang et al. 2013). Dynamic mechanical testing is done to determine the mechanical behavior and deformation of BnCs in the presence of high temperature. ...
... Porosity affects the mechanical properties of cement composites as well as the durability, where large size of pores reduces the mechanical properties and durability [38]. Porosity and pores size decrease with addition of CNTs into cement composites [39]. The small size of CNTs which is measured in Nano has ability to fill the pores hence decrease the porosity of cement composites. ...
Throughout the construction life, nanoparticles can change and modify the properties and functions of cement-based materials. The traditional cement materials have weak sustainability characteristics insufficient to develop high quality performance structures. Besides that, modifications of compressive and tensile strength and durability durations of cement composites are required. Consequently, a suitable range of Carbon nanotubes (CNTs) concentrations were applied to improve these certain properties. This review presents analysis of the earlier techniques of adding CNTs to cement composites and its influence to mechanical properties and durability. The detailed interactions of CNTs with cement composites, dispersion of CNTs, durability and mechanical performance measurements are addressed from several researches. CNTs addition contributes in adjustment of cement composite microstructures, hence improving the functional components and mechanical properties. If a proper dispersion of CNTs achieved, hydrate products of cement including C-S-H and Ca(OH) 2 interact with active CNTs, resulting in decrement of porosity of Portland cement composites which filled up by CNTs proportions leading to increase the mechanical strength. Therefore, this paper present state of the art regarding applications of the additive CNTs in cement composite, the reviewing results of CNTs-cements shows a positive influence on mechanical strength and durability.
... Since Iijima's description of carbon nanotubes appeared in 1991, numerous at-tempts have been made to use CNTs to strengthen materials, particularly polymers (e.g. [21,22]). ...
In recent years, there has been a growing interest in nanomaterials based on sp2-hybridized carbon across the field of material science. The focus of this dissertation is on carbon nano-tubes (CNTs), one of the many different types of carbon nanostructures known to date. It was expected that CNTs have a reinforcing effect, which impedes the initiation and development of cracks within a matrix, due to their high aspect ratio and exceptional mechanical properties. According to the theory of fiber-reinforced composites, investigating the surface properties of any material used as a fiber is necessary, as these properties are essential for adequate fiber-matrix bonding. Using a combination of several physical-chemical methods, it was deter-mined in this dissertation that the use of various carbon sources during synthesis, such as ace-tonitrile, methane and cyclohexane, led to the growth of carbon nanotubes which differed sig-nificantly from each other in respect to their wettability, surface tension and acid-base proper-ties. It was determined that the surface properties of CNTs are heavily dependent on the chemical composition of their surface. The experimental results showed that heteroatoms such as nitrogen and oxygen incorporated in the CNT structure imparted the CNTs with hydro-philic properties, while the pyrolysis residue, such as polycyclic aromatic hydrocarbons, de-posited on the CNT surface during growth in the CVD reactor increased the hydrophobic be-havior of the CNTs. The analyzed CNTs were subsequently coated with silica using a sol-gel method in order to improve their embedding in the cement matrix. It was observed that the deposition of a silica film on the CNTs' surface was strongly dependent on their surface prop-erties.
Another challenge of the application of carbon nanotubes as a reinforcing fiber is their uniform distribution within the cement paste, which is impeded by the CNTs' agglomeration. In the present dissertation, ultrasonic treatment was applied to disperse CNTs in aqueous solu-tions containing various types of surfactant and the resulting CNT dispersions were used to modify the cement paste. UV-vis spectroscopy was used to evaluate the CNTs' degree of dis-persion in water, while the functional relationships between variables, i.e., surfactant concen-tration, sonication duration and the light absorption measured for CNT dispersions, were de-termined by Design of Experiment (DOE) methods. The results of this study showed that CNTs are susceptible to breakage during ultrasonication. The significantly reduced length of the CNTs, some to only a few hundred nanometers, adversely affected their crack-inhibiting or crack-bridging properties when applied in microcrystalline hardened cement paste as a re-inforcing fiber. Thus, the anticipated significant increase in the tensile strength of the CNT-modified cement paste was not observed. It can be concluded from these results that CNTs are
iii
tendentially unsuitable for application as a reinforcing material in cement matrices due to their insufficient length.
The second part of the dissertation investigates the effect of oxidized CNTs and other carbon-based materials, such as mesoporous carbon and carbon black, on the hydration of the main material of Portland cement clinker, tricalcium silicate (3CaO∙SiO2, C3S), in its early stages. It is generally known that the reaction of C3S and water results in the formation of Ca(OH)2 and stable, insoluble calcium silicate hydrates, which are responsible for the harden-ing of the cement paste and early strength development of the hardened cement paste. It was discovered that carbon-based materials with a large specific surface and high surface density of oxygen-containing functional groups exert a catalytic effect on the hydration of C3S, re-gardless of their structural differences. The mechanism of the C3S hydration accelerated by carbon-based material was clarified by the example of mesoporous carbon and refutes the currently accepted hypothesis which states that the formation of stable C-S-H nuclei is a rate-determining step of C3S hydration.
The final part of the dissertation addresses the effect of carbon-based materials with active surfaces on the early strength of hardened cement paste. In order to determine the in-fluence of particle size on the process, a colloidal dispersion of graphene oxide with a layer thickness in the nanometer range, along with the carbon-based additives mentioned above, was examined. It can be deduced from the results of this study that the addition of nanoscale carbon-based materials with high surface density of oxygen-containing functional groups caused a rapid hardening of Portland cement. This finding is significant for the production of prefabricated concrete or steel-reinforced concrete elements, as it should make it possible to reduce the energy consumption used during their heat treatment.
... The results showed that the modulus of the PVA/3 wt% SWNT composite fiber was 40% higher than that of the control PVA gel spun fiber. Paiva et al. [28] functionalized SWCNTs with PVA and embedded into PVA matrix via a wet-casting method to fabricate polymer nanocomposite films with homogeneous nanotube dispersion. The tensile test results illustrated that PVA films with 5% functionalized SWCNT show an increase in elastic modulus and yield strength of approximately 55%, relative to pure PVA. ...
In this study, the elastic modulus of single-walled carbon nanotubes (SWCNTs)/epoxy nanocomposite was studied using the 3D finite element method and compared with experimental results to investigate the effect of SWCNTs interphase, curvature, and agglomeration on the prediction of the elastic modulus. Nanocomposite specimens containing 0.1, 0.3, and 0.5 wt% SWCNTs were fabricated to obtain SWCNTs/epoxy elastic modulus. The elastic modulus increased until SWCNTs was incorporated up to 0.3 wt% and after that, the trend of increasing elastic modulus declined. TEM images showed that in higher contents of filler, there were some local SWCNTs agglomerations within the composites which caused a dropped in elastic modulus of specimens containing 0.5 wt% SWCNTs. Also, six different 3D representative volume element (RVE) of SWCNTs/epoxy including incorporated cylindrical, cylindrical with agglomeration, curved-cylindrical, cylindrical with interphase, cylindrical with interphase and agglomeration and curved-cylindrical with agglomeration SWCNTs in the epoxy matrix have been generated using Digimat-FE and their elastic modulus evaluated by Digimat-FE solver. The numerical results cleared that the simplest cylindrical RVE has the greatest discrepancy with experimental results which showed the necessity of consideration of three important parameters including SWCNTs interphase, curvature, and agglomerations. By considering SWCNTs interphase and agglomeration the difference of numerical and experimental results decreased so that in specimens containing 0.1 wt% SWCNTs the error was only 6.8%. Also, the best results obtained from RVE of curved-cylindrical with agglomeration in specimen containing 0.1 wt% SWCNTs with only 4.1% error which showed the importance of considering SWCNTs agglomeration and curvature for modeling of nanocomposites.
... The mechanical characteristics of nanocomposites reinforced with conventional nanomaterials have been well studied in the literature. Earlier studies indicate that reinforcing a polymer or metallic sample with even marginal quantities of carbon nanotube (CNT) significantly enhances their mechanical strength [11][12][13][14]. Nanocomposites reinforced with graphene sheets have also been extensively researched [15][16][17][18]. ...
The discovery of hybrid boron nitride–carbon (BN–C) nanostructures has triggered enormous research interest in the design and fabrication of new generation nanocomposites. The robust design of these nanocomposites for target applications requires their mechanical strength to be characterized with a wide range of factors. This article presents a comprehensive study, with the aid of molecular dynamics analysis, of the tensile loading mechanics of BN–C nanosheet reinforced polyethylene (PE) nanocomposites. It is observed that the geometry and lattice arrangement of the BN–C nanosheet influences the tensile loading characteristics of the nanocomposites. Furthermore, defects in the nanosheet can severely impact the tensile loading resistance, the extent of which is determined by the defect’s location. This study also found that the tensile loading resistance of nanocomposites tends to weaken at elevated temperatures. The interfacial mechanics of the BN–C nanocomposites are also investigated. This analysis revealed a strong dependency with the carbon concentration in the BN–C nanosheet.
... Functionalization of the fillers commonly improves bonding between filler surface and matrix. In a work by Paiva et al. [224] SEM micrographs showed an apparent good wetting of water-soluble PVA-functionalized nanotubes by the PVA matrix. ...
Carbon-based nanoparticles have recently generated a great attention, as they could create polymer nanocomposites with enhanced transport properties, overcoming some limitations of electrically-conductive polymers for high demanding sectors. Particular importance has been given to the protection of electronic components from electromagnetic radiation emitted by other devices. This review considers the recent advances in carbon-based polymer nanocomposites for electromagnetic interference (EMI) shielding. After a revision of the types of carbon-based nanoparticles and respective polymer nanocomposites and preparation methods, the review considers the theoretical models for predicting the EMI shielding, divided in those based on electrical conductivity, models based on the EMI shielding efficiency, on the so-called parallel resistor-capacitor model and those based on multiscale hybrids. Recent advances in the EMI shielding of carbon-based polymer nanocomposites are presented and related to structure and processing, focusing on the effects of nanoparticle's aspect ratio and possible functionalization, dispersion and alignment during processing, as well as the use of nanohybrids and 3D reinforcements. Examples of these effects are presented for nanocomposites with carbon nanotubes/nanofibres and graphene-based materials. A final section is dedicated to cellular nanocomposites, focusing on how the resulting morphology and cellular structures may generate lightweight multifunctional nanocomposites with enhanced absorption-based EMI shielding properties.
... The additions of CNMs into polyvinyl alcohol (PVA) matrices have been studied and show the enhancement in term of mechanical properties. The tensile strength and Young's modulus of 5 wt% PVA-functionalized SWCNTs to a PVA matrix by a wet-casting method were improved by 54% and 55%, respectively, compared to pure PVA [30]. However, the mixing between GO and PVA by 1 wt% net GO shows higher increment in tensile strength and Young's modulus by 88% and 150%, respectively, as compared to pure PVA [31]. ...
... Paiva et al. [156] performed a mechanical characterization of polymerÀcarbon nanocomposites under torsion. For such a characterization, they functionalized the CNTs with poly (vinyl alcohol) (PVA) and then, produced the nanocomposite films with homogeneous nanotube dispersion by embedding the water-soluble PVAÀfunctionalized CNTs into the polymer matrix. ...
In this chapter, different concepts from production to the characterization of carbon
nanotubes (CNTs) are described. The construction of the actual chapter mainly
starts with the description and comparison of the common synthesis techniques i.e.
arc discharge, laser ablation, chemical vapour deposition (CVD), flame synthesis,
and silane solution methods for the production of the CNTs, followed by the purification
process and application potentials of these nanomaterials. Then, a fundamental
demonstration and insight in the atomic structure of main CNT configurations
(armchair, zigzag and chiral) is provided. In the subsequent subsection, various
defect types, classified into two general groups of macroscopic disorders (curvature,
twist and hetero-junction kink) and atomic scale defects (vacancies, impurities, perturbation
and Stone-Wales defect), and their influence on the properties of CNTs as
well as functionalization of CNTs and harvesting these defects for various applications
are elucidated. Finally, the experimental and theoretical CNT characterization
approaches are discussed and the pertaining results in the literature are presented.
The results from literature reveals the fact that these nanostructures, not only
involve different defect and disorder types from their synthesis process which
reduce their individual mechanical stabilities and often necessitate purification process
for their redundant impurities and by-products removal, but also from their
functionalization process in which particular defects i.e. adatom doping and multi-
CNT welding through hetero-junctions are intentionally employed for enhancing
the properties and functionality of the CNTs for various applications from energy
storing, gas detection and materials reinforcement to drug delivery and molecules
transportation.
Though concrete is one of the most widely used construction materials, there are some concerns and shortcomings associated with it. Cementitious materials' quasi-brittle behavior, which leads to cracking and a loss of durability, is a major concern in structural applications. In this review, the latest research on reinforcing cementitious concrete with carbon nanotubes (CNTs) is reviewed, with an emphasis on the material's structural performance in building and a comparison of CNTs to other reinforcing fibers. The improvement of the macro mechanical properties of carbon nanotube-reinforced composite structures has been discussed in the form of functionally graded carbon nanotubes reinforced composites (FG-CNTRC). Several researches have, in the past, used other forms of reinforcements to enhance the properties of concrete till the implementation of nanotechnology in concrete production by incorporating CNTs into the concrete mixes. Concrete's crucial mechanical properties as a structural material and the durability of conventional cement-based building materials can both be improved by CNTs. They have drawn a lot of interest because they are an engineering material with a wide range of uses. The creation and characterization of cement-based materials reinforced with CNTs have been studied by researchers. Comparisons between the effects of CNT and other fibers on concrete have also been made. This concrete reinforcement type's environmental impact and sustainability have also been discussed. According to studies, CNT can greatly enhance the performance of cement-based materials.
Nanoscale recombination between carbon nanomaterials (CNs) and polymers has been proposed for a variety of industrial and scientific applications. Composite energetic materials consisting of CNs with novel laser ignition property and tunable combustion performance have attracted people's attention. Here, reported is the novel manufacturing process of uniform nitrocellulose (NC)/graphene oxide (GO) nanocomposite propellant and the micro‐structure, laser ignition and isovolumetric burning features of the propellants introduced by GO. The results of microstructure tests indicated that GO (0.25–2 wt%) was stripped and dispersed homogeneously and dense nanocomposite propellants were prepared successfully through water ultrasonic dispersion, twin‐screw mixture, as well as compression molding. The crystallization of NC was forbidden by doping GO, meanwhile, the thermal stability and thermal conductivity of the composite propellants increased slightly with the addition of GO. The results of laser ignition combustion experiments showed that GO was an efficient additive to shorten the ignition delay time from more than 2000–14 ms when 2 wt% of GO was doped, however, the combustion flame intensity was also weakened due to the addition of GO. The combustion tests in a closed bomb vessel were conducted, and the results showed that GO would not affect the stable combustion of NC at high combustion pressure, moreover, the burning rate and dynamic vivacity of the composite propellants decreased with the increase of GO content.
Membrane distillation is a promising technology for recovering resources and water from brackish water and wastewater. However, characteristics of current membranes limit the employment of membrane distillation in these areas. In this paper, activated carbon modified membrane has been studied. Agglomeration of activated carbon (AC) particles in the membrane matrices has negative influence on the performance of AC/PVDF composite membrane. To solve this problem in this study, the AC was functionalized with fluoroalkyl groups via the reaction between carboxylic activated carbons and octafluoropentanol (OFP). The AC-OFP/PVDF composite membrane was prepared by blending PVDF and the functionalized AC-OFP particles via a conventional phase-inversion method. In comparison with the AC particles, the dispersion of AC-OFP particles in membrane matrix was improved greatly. The maximum DCMD flux increased from 29.8 kg/m²h (AC/PVDF membrane) to 40.4 kg/m²h (the AC-OFP/ PVDF membrane) by just adding 0.15 wt% AC-OFP particles.
The world is looking for the new materials because of rapid industrialization, specific needs and demands from the people. Glass fiber reinforced polymer composites are the promising materials from few decades. Glass fibers reinforced polymer composites have been prepared by various manufacturing techniques and are widely used for various applications. Nowadays, it has been used in electronics, aviation and automobile application. Glass fibers are having excellent properties like high strength, flexibility, stiffness and resistance to chemical harm. Each type of glass fibers have unique properties and are used for various applications in the form of polymer nano-composites. Nano materials in polymer nano-composites (PNC) play major role in mechanical properties. PNC’s are one of the novel materials, which give better functional properties than other materials. Fatigue failure in complex structures cannot be predicted earlier. Fatigue cracks can be initiated and propagated at stresses well below the yield strength of the material. In this paper, it is explained the fatigue behavior of PNC’s using FEA solver to determine the strength properties and to compare both analytical and experimental values of fatigue testing.
Bio-based materials have attracted ample research interest due to their intrinsic beneficial impact on human society. Microcrystalline cellulose (MCC) extracted from a variety of bioresources is one of the most prominent candidate in this regard. Herein, the MCC was synthesized from jute fiber by a facile ammonium persulfate (APS) oxidation method resulting in carboxylic functional groups on the fiber surface. The carboxylated MCC was utilized to develop polyvinyl alcohol (PVA) composite films in a solution casting method. The surface chemistry, thermal properties, and surface morphology of MCC and MCC-PVA composite films were studied by FT-IR spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The SEM images confirmed the rod-like MCC with average particle diameter 4.6 μm and length in 48.4 μm. The FT-IR spectroscopy suggested the complete removal of lignin and hemicellulose from jute fiber. A peak at 1730 cm ⁻¹ was introduced in MCC due to oxidation with APS. The MCC was readily dispersible in water, and chemical interaction with –OH group of PVA was spontaneous due to the carboxylation in MCC. The absorption peak of –OH groups in MCC-PVA composite films were shifted, somewhat disappeared and weakened due to the intra and intermolecular hydrogen bonding of MCC and OH groups in PVA. Thermogravimetric analysis expressed the thermal behavior of MCC and MCC-PVA composite films. The char formation at 500°C of the two different composite films was 15% and 16%, respectively. The stability of MCC-PVA composite films at elevated temperatures is the indication of potential application as flame retardant material.
Polymer components capable of self-healing can rapidly be manufactured by injecting the monomer (ε-caprolactam), activator and catalyst mixed with a small amount of magnetic nanoparticles into a steel mould. The anionic polymerisation of the monomer produces a polymer component capturing magnetic nanoparticles in a dispersed state. Any microcracks developed in this nanocomposite component can be healed by exposing it to an external alternating magnetic field. Due to the magnetocaloric effect, the nanoparticles locally melt the polymer in response to the magnetic field and fill the cracks, but the nanoparticles require establishing a network within the matrix of the polymer through effective dispersion for functional and uniform melting. The dispersed nanoparticles, however, affect the degree of crystallinity of the polymer depending on the radius of gyration of the polymer chain and the diameter of the magnetic nanoparticle agglomerates. The variation in the degree of crystallinity and crystallite size induced by nanoparticles can affect the melting temperature as well as its mechanical strength after testing for applications, such as stimuli-based self-healing. In the case of in situ synthesis of the polyamide-6 (PA6) magnetic nanocomposite (PMC), there is an opportunity to alter the degree of crystallinity and crystallite size by optimising the catalyst and activator concentration in the monomer. This optimisation method offers an opportunity to tune the crystallinity and, thus, the properties of PMC, which otherwise can be affected by the addition of nanoparticles. To study the effect of the concentration of the catalyst and activator on thermal properties, the degree of crystallinity and the crystallite size of the component (PMC), the ratio of activator and catalyst is varied during the anionic polymerisation of ε-caprolactam, but the concentration of Fe3O4 nanoparticles is kept constant at 1 wt%. Differential Scanning Calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), XRD (X-ray diffraction) and Thermogravimetric analysis (TGA) were used to find the required concentration of the activator and catalyst for optimum properties. It was observed that the sample with 30% N-acetyl caprolactam (NACL) (with 50% EtMgBr) among all of the samples was most suitable to Rapid Prototype the PMC dog-bone sample with the desired degree of crystallinity and required formability.
Comparative studies on the mechanical behavior of the composites of polyvinyl alcohol (PVA) polymer with different carbon fillers such as multiwalled carbon nanotube (MWCNT), functionalized CNT (f‐CNT), and short carbon fiber (Cf), having similar geometry (1D) but different length scale, have been carried out. Microstructural analysis reveals better distribution of second phases with f‐CNT and Cf compared with MWCNT. Fourier‐transform infrared spectra indicate the interaction of functional groups of CNTs with the polymeric chain of PVA. X‐ray diffraction analysis shows improvement of crystallinity upon addition of carbon filler. Defect analysis of carbon reinforcement is carried out using Raman spectroscopy. The strength of the composite is increased by 138% with MWCNT reinforcement, by 201.8% with f‐CNT reinforcement, and by 87.9% with Cf reinforcement. The fractographs show pullout, branching, and bridging as strengthening mechanisms for MWCNT and f‐CNT in the PVA matrix, whereas mainly pullout as strengthening mechanism for Cf–PVA composite.
Carbon nanotubes (CNTs) are noteworthy, as they reinforce the metallic matrix, due to mechanical properties, such as the ~ 1.0 TPa Young module. To improve the maintenance of the commercially pure aluminum surface, multi-walled carbon nanotubes were incorporated into the aluminum surface with heat treatment by solid solubilization, in order to improve the surface properties of aluminum. The aluminum samples were chemically attacked for 30, 60 and 120 s and placed in a container with CNTs, being subjected to a temperature of 640 °C for 1 h. Then, the roughness was evaluated by a roughness meter for morphology in the scanning electron microscopy. An intensity of aggregation of CNTs was evaluated by XRD, and the Raman Spectra has evaluated the transfer of charge to the matrix. Microhardness was performed to evaluate the influence of the incorporation of CNTs in the matrix. The results obtained show that the incorporation of CNTs in the aluminum matrix increases the hardness in approximately 20% of the surface, in comparison with the control sample. The process of incorporating CNTs into the aluminum matrix by solubilization is a promising, simple and inexpensive alternative to improve the durability of the aluminum surface.Graphic Abstract
The use of conventional carbon-based nanofillers such as carbon nanotubes (CNTs) and graphene sheets can be hindered to a certain extent when considering a high level of nanotoxicity via human inhalation and less cost-effectiveness for CNTs while the agglomeration of graphene sheets in polymer matrices. As such, bamboo charcoals (BCs) are suggested as alternative ecofriendly and sustainable carbon-based particles with good affinity to polyvinyl alcohol (PVA) as one of most popular water-soluble biopolymers in order to prepare PVA/BC bionanocomposites with superior material properties. In this chapter, two different types of BC particles, namely microdiameter bamboo charcoals (MBCs) and nanodiameter bamboo charcoals (NBCs), were successfully fabricated using a solution casting method. Nanofiller reinforcement effect was investigated with respect to BC particle size and dispersion, morphological structures and interfacial interactions between BCs and PVA matrices in such bionanocomposites. Overall, the addition of NBCs gave rise to much higher mechanical properties of PVA/NBC bionanocomposites as opposed to PVA/MBC counterparts. The maximum increases in tensile moduli of bionanocomposites were achieved up to 123 and 100% with the inclusion of 10 wt% NBCs and MBCs, respectively. Furthermore, corresponding tensile strengths were enhanced by 110 and 72% when incorporated with 3 wt% NBCs and MBCs accordingly, as compared with that of PVA. It is convincing that associated particle dispersion states within PVA matrices, as well as interfacial interaction between BCs and PVA matrices play a leading role in the remarkable property enhancement in PVA/BC bionanocomposites, which can be potentially used in material packaging and biomedical applications.
The effect of multi-walled carbon nanotubes (MWCNT) coating in the presence of polyethyleneimine (PEI) of different molecular weights (MW) on the interfacial shear strength (IFSS) of carbon fiber/acrylonitrile–butadiene–styrene (ABS) and carbon fiber/epoxy composites was investigated. The IFSS between the carbon fiber and the polymer was evaluated by means of single fiber microbonding test. The results indicated that uses of the carbon fibers uncoated and coated with pristine, low MW PEI-treated, and high MW PEI-treated MWCNT significantly influenced the IFSS of both thermoplastic and thermosetting carbon fiber composites as well as the carbon fiber surface topography. The incorporation of low MW (about 1300) PEI into the carboxylated MWCNT was more effective not only to uniformly coat the carbon fiber with the MWCNT but also to improve the interfacial bonding strength between the carbon fiber and the polymer than that of high MW (about 25,000) PEI. In addition, carbon fiber/epoxy composite exhibited the IFSS much higher than carbon fiber/ABS composite due to the chemical interactions between the epoxy resin and amine groups existing in the PEI-treated MWCNT.
Nanocomposites have been researched and commercially applied for approximately 60 years due to their advanced properties compared to others (i.e neat materials, alloys) such as mechanical properties, thermal and electrical conductivity. Moreover, the exceptionally high strength-to-weight ratio of nanocomposites makes them suitable candidates for manufacturing micro-features. Among different micro-manufacturing techniques (i.e lithography, laser micromachining), mechanical micromachining has been found as a potential adaption in manufacturing nanocomposites in terms of machined surface quality, dimensional accuracy and feasibility for a wide range of workpiece materials. However, mechanical micromachining of nanocomposites is deemed to be a complicated process due to the anisotropic, heterogeneous structure and advanced mechanical properties (i.e high stiffness, strength, hardness) of these materials associated with the size effects in micromachining [1]. It leads to lower machinability in terms of high cutting force, machined surface roughness and tool wear. Therefore, a comprehensive discussion on mechanical properties of typical nanocomposites and their subsequent micro-machining processes are presented within this review based on relevant studies for both experimental and simulated results. From this review, general trends of micromachining nanocomposites, as well as their recent limitations, are indicated.
The potential for the material property improvement through the addition of carbon nanotubes (CNTs) in composite materials is often limited due to CNT agglomeration. In this work, Disperse Orange 3 (DO3) was investigated to determine its effectiveness in dispersing CNTs in a poly (lactic acid) (PLA) matrix. First, adsorption studies of DO3 onto CNTs were performed to determine the appropriate amount of DO3 to add so that the CNT surface will be nearly saturated with DO3 while limiting the excess DO3 dissolved in the polymer. The resultant improvements in the mechanical properties were determined via nanoindentation. Highly stable dispersion of CNTs in tetrahydrofuran with DO3 was observed 72 hours after sonication. Scanning electron microscopy confirmed that DO3-functionalized CNTs were able to separate and disperse well inside of the PLA matrix. Addition of DO3 to the nanocomposite resulted in an increase in the glass transition temperature and crystallinity of the composite due to the more effective dispersion of the nanofiller which serves as a nucleation agent. The CNTs treated with DO3 also increased the elastic modulus and hardness of the composite compared to neat PLA and untreated PLA-CNT composites. From this study, DO3 was demonstrated to be an effective dispersing agent in the solvent and the PLA matrix which allowed for enhanced crystallization and improved nanomechanical properties in the resultant composite.
In this article, we present a finite element model for the three-dimensional analysis of smart constrained layer damping of geometrically nonlinear vibrations of laminated fuzzy-fiber reinforced composite plates. The three-dimensional fractional derivative constitutive relation is implemented for the viscoelastic layer. The constraining layer of the smart constrained layer damping treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composites. The von Kármán–type nonlinear strain–displacement relations are used to incorporate the geometric nonlinearity in the model. The main aim of this article is to numerically investigate the effect of carbon nanotube waviness on the nonlinear smart damping. Several thin laminated substrate fuzzy-fiber reinforced composite plates with straight carbon nanotubes and wavy carbon nanotubes with different waviness in different planes are considered with various boundary conditions and stacking sequences to numerically compute their effect on smart damping. The performance of the obliquely reinforced 1–3 piezoelectric composites is discussed and the efficacy of the present smart finite element model in terms of active control authority is also presented.
Cellulose is world's most abundant, renewable and recyclable polysaccharide on earth. Cellulose is composed of both amorphous and crystalline regions. Cellulose nanocrystals (CNCs) are extracted from crystalline region of cellulose. The most attractive feature of CNC is that it can be used as nanofiller to reinforce several synthetic and natural polymers. In this article, a comprehensive overview of modification of several natural and synthetic polymers using CNCs as reinforcer in respective polymer matrix is given. The immense activities of CNCs are successfully utilized to enhance the mechanical properties and to broaden the field of application of respective polymer. All the technical scientific issues have been discussed highlighting the recent advancement in biomedical and packaging field.
In this chapter, the discussion has been made on some important methodologies to prepare polymer/carbon composites. These procedures are solution mixing technique, melt mixing technique, in situ polymerization technique, dry mixing technique, powder mixing technique, and aqueous mixing technique. Solution mixing has been categorized into evaporative casting, vacuum filtration, 3D printing, and wet spinning. In the melt mixing process, the discussion has been focused on melt blending through internal mixer and melt spinning. Some diagrams have been drawn and discussed for better understanding of the composite preparation processes. The advantages and disadvantages associated with the composite preparation processes are mentioned herein where necessary.
In this work, multimalled carbon nanotubes were investigated as potential mechanical reinforcement agents in two. hosts, polyvinyl alcohol (PVA) and poly(9-vinyl carbazole) (PVK). It was found that, by adding various concentrations of nanotubes, both Young's modulus and hardness increased by factors of 1.8 and 1.6 at 1 wt% in PVA and 2.8 and 2.0 at 8 wt% in,PVK, in reasonable agreement with the Halpin-Tsai theory. Furthermore, the presence of the nanotubes was found to nucleate crystallization of the PVA. This crystal growth is thought to enhance matrix-nanotube stress transfer. In addition, microscopy studies suggest extremely strong interfacial bonding in the PVA-based composite. This is manifested by the fracture of the polymer rather that the polymer-nanotube interface. (C) 2002 American Institute of Physics. [DOI:10.1063/1.1533118].
Single-walled carbon nanotubes (SWNTs) offer the prospect of both new
fundamental science and useful (nano)technological applications. High
yields (70-90%) of SWNTs close-packed in bundles can be produced by
laser ablation of carbon targets. The electric-arc technique used to
generate fullerenes and multi-walled nanotubes is cheaper and easier to
implement, but previously has led to only low yields of SWNTs,. Here we
show that this technique can generate large quantities of SWNTs with
similar characteristics to those obtained by laser ablation. This
suggests that the (still unknown) growth mechanism for SWNTs must be
independent of the details of the technique used to make them. The ready
availability of large amounts of SWNTs, meanwhile, should make them much
more accessible for further study.
Fullerene single-wall nanotubes (SWNTs) were produced in yields of more than 70 percent by condensation of a laser-vaporized carbon-nickel-cobalt mixture at 1200degreesC. X-ray diffraction and electron microscopy showed that these SWNTs are nearly uniform in diameter and that they self-organize into "ropes," which consist of 100 to 500 SWNTs in a two-dimensional triangular lattice with a lattice constant of 17 angstroms. The x-ray form factor is consistent with that of uniformly charged cylinders 13.8 +/- 0.2 angstroms in diameter. The ropes were metallic, with a single-rope resistivity of <10(-4) ohm-centimeters at 300 kelvin. The uniformity of SWNT diameter is attributed to the efficient annealing of an initial fullerene tubelet kept open by a few metal atoms; the optimum diameter is determined by competition between the strain energy of curvature of the graphene sheet and the dangling-bond energy of the open edge, where growth occurs. These factors strongly favor the metallic (10,10) tube with C5v symmetry and an open edge stabilized by triple bonds.
Single wall carbon nanotubes (SWNTs) that are found as close-packed arrays in crystalline ropes have been studied by using Raman scattering techniques with laser excitation wavelengths in the range from 514.5 to 1320 nanometers. Numerous Raman peaks were observed and identified with vibrational modes of armchair symmetry (n, n) SWNTs. The Raman spectra are in good agreement with lattice dynamics calculations based on C-C force constants used to fit the two-dimensional, experimental phonon dispersion of a single graphene sheet. Calculated intensities from a nonresonant, bond polarizability model optimized for sp2 carbon are also in qualitative agreement with the Raman data, although a resonant Raman scattering process is also taking place. This resonance results from the one-dimensional quantum confinement of the electrons in the nanotube.
Single wall carbon nanotubes (SWNTs) that are found as close-packed arrays in crystalline ropes have been studied by using
Raman scattering techniques with laser excitation wavelengths in the range from 514.5 to 1320 nanometers. Numerous Raman peaks
were observed and identified with vibrational modes of armchair symmetry (n, n) SWNTs. The Raman spectra are in good agreement with lattice dynamics calculations based on C-C force constants used to fit
the two-dimensional, experimental phonon dispersion of a single graphene sheet. Calculated intensities from a nonresonant,
bond polarizability model optimized for sp2 carbon are also in qualitative agreement with the Raman data, although a resonant Raman scattering process is also taking
place. This resonance results from the one-dimensional quantum confinement of the electrons in the nanotube.
Multiwall carbon nanotubes have been dispersed homogeneously throughout polystyrene matrices by a simple solution-evaporation method without destroying the integrity of the nanotubes. Tensile tests on composite films show that 1 wt % nanotube additions result in 36%-42% and ~25% increases in elastic modulus and break stress, respectively, indicating significant load transfer across the nanotube-matrix interface. In situ transmission electron microscopy studies provided information regarding composite deformation mechanisms and interfacial bonding between the multiwall nanotubes and polymer matrix.
Carbon single walled nanotubes (SWNTs) have been produced in high yields using the electric arc technique. TEM studies show that the SWNTs have a narrow diameter distribution around an average value of 1.3 nm. In this paper, we focus on the characterization of these samples by high resolution Raman spectroscopy (HRRS). The presence of large amounts of SWNTs in the samples induces a very rich structure in the Raman spectra, typical for this class of carbonaceous material. Armchair tubes with (8,8) to (12,12) geometry can be detected, in agreement with the narrow diameter distribution observed by TEM measurements. The ability of HRRS as a highly sensitive fingerprint technique in identifying SWNTs with different diameters and geometries is discussed.
Poly(vinyl alcohol) (PVA) composite films using poly(vinyl pyrrolidone) (PVP) and sodium dodecyl sulfate (SDS)-covered, well dispersed single wall carbon nanotubes (SWNT) exhibit significant improvement in tensile strength and modulus as compared to the control PVA and PVA/PVP/SDS films. The evidence of load transfer to the nanotubes in the composite film has been obtained from the shift in the Raman SWNT D* band peak position.
Carbon nanotube-containing poly(phenylacetylenes) (NT/PPAs) are prepared by in situ polymerizations of phenylacetylene catalyzed by WCl6−Ph4Sn and [Rh(nbd)Cl]2 (nbd = 2,5-norbornadiene) in the presence of the nanotubes. The NT/PPAs are characterized by GPC, NMR, UV, FL, TGA, SEM, TEM, and XRD, and it is found that the nanotubes in the NT/PPAs are helically wrapped by the PPA chains. The short nanotubes thickly wrapped in the PPA chains are soluble in common organic solvents including tetrahydrofuran, toluene, chloroform, and 1,4-dioxane. The NT/PPAs are macroscopically processible, and shearing of the NT/PPA solutions readily aligns the nanotubes along the direction of the applied mechanical force. The nanotubes exhibit a strong photostabilization effect, protecting the PPA chains from photodegradation under harsh laser irradiation with incident fluence as high as 10 J/cm2. The NT/PPA solutions effectively limit intense optical pulses, with the saturation fluence tunable by varying the nanotube contents.
Single-walled and multiple-walled carbon nanotubes were functionalized with poly(vinyl alcohol) (PVA) in esterification reactions. Similar to the parent PVA, the functionalized carbon nanotube samples are soluble in highly polar solvents such as DMSO and water. The common solubilities have allowed the intimate mixing of the functionalized nanotubes with the matrix polymer for the wet-casting of nanocomposite thin films. The PVA−carbon nanotube composite films are of high optical quality, without any observable phase separation, and the carbon nanotubes in the films are as well-dispersed as in solution. The functionalization of carbon nanotubes by the matrix polymer is apparently an effective way in the homogeneous nanotube dispersion for high-quality polymeric carbon nanocomposite materials. Results from characterizations of the solubilized carbon nanotubes and the nanocomposite thin films are presented and discussed.
Single-walled and multiple-walled carbon nanotubes were functionalized with a polystyrene copolymer, poly(styrene-co-p-(4-(4‘-vinylphenyl)-3-oxabutanol)). The functionalization reaction conditions were designed for the esterification of the nanotube-bound carboxylic acids. The polymer-attached carbon nanotubes are soluble in common organic solvents, making it possible to characterize the samples using not only solid-state but also solution-based techniques. The solubility has also allowed an intimate mixing of the functionalized carbon nanotubes with polystyrene. Results from the characterization of the functionalized carbon nanotubes, including the chemical and thermal defunctionalizations of the soluble samples, and the fabrication of polystyrene−carbon nanotube composite thin films using a wet-casting method are presented and discussed.
Polystyrene nanocomposites with functionalized single-walled carbon nanotubes (SWNTs), prepared by the in-situ generation and reaction of organic diazonium compounds, were characterized using melt-state linear dynamic viscoelastic measurements. These were contrasted to the properties of polystyrene composites prepared with unfunctionalized SWNTs at similar loadings. The functionalized nanocomposites demonstrated a percolated SWNT network structure at concentrations of 1 vol % SWNT, while the unfunctionalized SWNT-based composites at twice the loading of SWNT exhibited viscoelastic behavior comparable to that of the unfilled polymer. This formation of the SWNT network structure for the functionalized SWNT-based composites is because of the improved compatibility between the SWNTs and the polymer matrix and the resulting better dispersion of the SWNT.
Are nanotubes ideally suited to a straightforward reinforcing role? Results reported here indicate that that may not be the case, but they could find application as a polymer modifier. A successful route is described for the fabrication of large composite films containing carbon nanotubes based on the formation of a stable colloidal intermediate, a route that should be broadly applicable to a range of nanotube materials and polymers. The resulting thermo-mechanical and electrical properties are discussed. While the stiffness of the composites at room temperature is rather low they show promise at high temperatures.
Poly(p-phenylene benzobisoxazole) (PBO) has been synthesized in the presence of single-wall carbon nanotubes (SWNTs) in poly(phosphoric acid) (PPA) using typical PBO polymerization conditions. PBO and PBO/SWNT lyotropic liquid crystalline solutions in PPA have been spun into fibers using dry-jet wet spinning. The tensile strength of the PBO/SWNT fiber containing 10 wt % SWNTs is about 50% higher than that of the control PBO fibers containing no SWNTs. The structure and morphology of these fibers have been studied.
Intimate electrical contact occurs between a substituted poly(metaphenylenevinylene) (PmPv) and bundles of single-walled nanotubes (SWNT) as evidenced by atomic force microscopy, optical, and electronic measurements carried out on single, isolated SWNT/PmPv structures (see picture). PmPV may provide a useful route toward "functionalizing" the SWNT without destroying their electrical character.
The disorder-induced D-band and some other non-zone center Raman modes of graphite and single wall carbon nanotubes are assigned to phonon modes in their respective Brillouin zones. In disordered graphite, the weak, dispersive phonon modes, which have been known but never assigned so far, are well described by the double resonance Raman process. All weak Raman peaks observed for sp2 carbons are useful for determining the phonon dispersion relations of graphite. In carbon nanotubes, all semiconducting nanotubes and some metallic nanotubes have van Hove singular k points for their electronic and phonon energy dispersion curves at the Γ point of the Brillouin zone. A corresponding Raman process is relevant to explain the observed D-band and intermediate frequency spectra.
Since their first observation nearly a decade ago by Iijima (Iijima S. Helical microtubules of graphitic carbon Nature. 1991; 354:56–8), carbon nanotubes have been the focus of considerable research. Numerous investigators have since reported remarkable physical and mechanical properties for this new form of carbon. From unique electronic properties and a thermal conductivity higher than diamond to mechanical properties where the stiffness, strength and resilience exceeds any current material, carbon nanotubes offer tremendous opportunities for the development of fundamentally new material systems. In particular, the exceptional mechanical properties of carbon nanotubes, combined with their low density, offer scope for the development of nanotube-reinforced composite materials. The potential for nanocomposites reinforced with carbon tubes having extraordinary specific stiffness and strength represent tremendous opportunity for application in the 21st century. This paper provides a concise review of recent advances in carbon nanotubes and their composites. We examine the research work reported in the literature on the structure and processing of carbon nanotubes, as well as characterization and property modeling of carbon nanotubes and their composites.
High-purity aligned multi-walled carbon nanotubes (MWNTs) were synthesized through the catalytic decomposition of a ferrocene–xylene mixture at ∼675°C in a quartz tube reactor and over quartz substrates, with a conversion of ∼25% of the total hydrocarbon feedstock. Under the experimental conditions used, scanning electron microscope images reveal that the MWNT array grows perpendicular to the quartz substrates at an average growth rate of ∼25 μm/h. A process of this nature which does not require preformed substrates, and which operates at atmospheric pressure and moderate temperatures, could be scaled up for continuous or semi-continuous production of MWNTs.
Carbon nanotubes can be functionalized via amidation and esterification of the nanotube-bound carboxylic acids. The solubility of these functionalized carbon nanotubes makes it possible to characterize and study the properties of carbon nanotubes using solution-based techniques. Representative results concerning the solubility, dispersion, defunctionalization, and optical properties of the functionalized carbon nanotubes are presented. Several examples for the use of functionalized carbon nanotubes in the fabrication of polymeric carbon nanocomposites, the probing of nanotube-molecule interactions, and the conjugation with biological species are highlighted and discussed.
Fabrication and characterization of carbon nanotube/poly (vinyl alcohol) composites Morphological and mechanical properties of carbon-nanotubereinforced semicrystalline and amorphous polymer composites Poly(vinyl alcohol)/SWNT composite film
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