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FTIR spectra of (a) CNT and (b) CNT functionalized by chemical treatment. Bellow the magnified spectra from 1850–1500 cm−1. Inset: structures of CNT before and after carboxylic functionalization (CNT–COOH).
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This study reports the synthesis and characterization of novel tridimensional porous hybrids based on PVA combined with bioactive glass and reinforced by chemically functionalized carbon nanotubes (CNT) for potential use in bone tissue engineering. The functionalization of CNT was performed by introducing carboxylic groups in multiwall nanotubes. T...
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... this work a treatment with HNO 3 was used to functionalize CNT with carboxylic groups. Figure 1 presents the FTIR spectra of CNT before and after the chemical treatment. In the modified CNT spectrum a band at 1745 cm −1 can be observed which corresponds to the stretching vibration of carboxyl groups (-COOH) introduced. ...Similar publications
Silicon-boron based glass was prepared by sol gel method. This bioactive glass (70-x) SiO 2-6P 2 O 5-24CaO and (x) B 2 O 3 in which SiO 2 substituted by B 2 O 3 with variated values x = 0, 5, 10, 15, 20 and 25 wt %. The morphology of the 600 0 C heat treated samples was characterized through SEM, EDX, XRD and FTIR. The bioactive glass have been ana...
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... In this method, CNTs interact with modifier through various adsorption forces, such as hydrogen bonds, van der Waals and electrostatic force, and p-stacking (Meng et al., 2009). With respect to noncovalent modification, in covalent functionalization, functional ÀCOOH or OH groups can be formed on CNT surface which a broad range of functional groups could be merged onto the surface of CNTs by more adaptable modification approaches (Mansur et al., 2012;Gao et al., 2011). ...
Fiber plastic composite (FPC) is a very promising and sustainable green material to achieve durability without using toxic chemicals. The term FPCs refers to any composites that contain plant fiber and thermosets or thermoplastics. Plant fibers are interesting reinforcement, due to their specific properties such as low density, high strength, and nonabrasiveness during processing. Furthermore, they are low cost, renewable, abundant, and biodegradable. Due to the worldwide shortage of trees in many areas and environmental awareness, research on the development of composites prepared using various nonwood fibrous materials is being actively pursued. Among the possible alternatives, the development of composites using agricultural byproducts or agro-waste materials (including stalks of most cereal crops, rice husks, coconut fibers, bagasse, maize cobs, peanut shells, and other wastes) is currently at the center of attention. Use of agro-waste materials as a reinforcement in the production of FPCs alleviate the shortage of wood resources.
... The very dense or less porous microstructure of alginate could limit the diffusion of SWCNTs inside the matrix. Although the transport of SWCNTs into the PVA beads might be facilitated by the highly macroporous structure of the matrix, PVA may form a crystalline coating around CNTs (Mansur et al., 2012) which might reduce their antibacterial effect. Another possible reason for the similar effect of alginate and PVA entrapments is that the majority of the entrapped cells were in the inner part of the beads. ...
... Additionally, the band in the range from 1720 to 1750 cm À1 related to the stretching vibration from the carboxyl groups (-COOH) [35] is present but relatively much more evident in the nanotubes after the chemical functionalization (MWNT-F; Figure 3b). These results have clearly indicated that the process based on the reaction of strong Nanocomposites for Potential Application as Scaffolds in Skin Wound Healing 189 inorganic acid was effective on covalently attaching carboxylic groups to originally hydrophobic carbon nanotubes. ...
A novel nanocomposite scaffold based on poly(vinyl alcohol) (PVA) and multiwalled carbon nanotubes (MWNT) were synthesized and characterized regarding to morphological, physical, and mechanical properties and also the preliminary biocompatibility was assessed by MTT assay. Additionally, the concept of developing hybrid systems was tested by bioconjugating functionalized MWNT to glucose oxidase and dispersed in the PVA matrix. The nanocomposites have presented mechanical properties, degree of swelling, and cytocompatibility comparable to the skin tissues. Moreover, the bionanocomposite with enzyme showed bioactivity toward injecting glucose with simultaneous antimicrobial behavior against bacterial pathogens due to the generation hydrogen peroxide.
Hybrid membranes, featuring combinations of inorganic and organic materials at the nanometre or molecular level, have been widely reported as providing superior separation performance compared with the traditional polymeric membranes. However, for rational design of membranes, there remains a major doubt as to how each constituent functions in the separation process. Herein, carbon nanotube (CNT) incorporated poly (vinyl alcohol) (PVA) membranes were analysed using pervaporation (PV) process for aqueous mixture separation. The impacts of CNT on the functional properties, morphologies and microscale structures of the PVA/CNT hybrid membranes was investigated by ATR-FTIR, AFM, SEM and positron annihilation lifetime spectroscopy (PALS). Further, a comparison of the interactions between the membrane and solvents (water and ethanol) were identified by swelling test and XRD. The resultant PVA/CNT hybrid membranes were then subject to both desalination and dehydration of ethanol. The results showed that PVA exhibited preferential adsorption of water over ethanol. The addition of CNT enlarged the fractional free volume (FFV) and enhanced water diffusivity (up to 185%), which indicated a diffusion-dominated type of the PVA/CNT hybrid membranes with a synergistic effect of CNT on water transport. The transport of Na⁺ ions through the membrane was examined to be with larger activation energy than that of ethanol during the separation process. This work investigated the state of polymer as well as the effect of nanofillers in the separation of water vs. non-volatile or volatile component for the first time, which can provide in-depth understanding of the polymer-based hybrid membranes for practical applications.
Hybrid multiscale fiber reinforced epoxy composite laminates were developed and characterized from woven glass fiber mats reinforced with nonwoven PAN nanofibers (diameters of 200 nm) produced via electrospinning. An electrospinning setup was designed and developed to produce continuous E‐spun nonwoven nanofiber (NWNF) mats, which were then used as interlaminar reinforcements for producing multiscale hybrid composites. A detailed study for producing E‐spun nanomats considering both solution and operation parameters was undertaken discussed and optimum spinning parameters were obtained. These parameters were used to produce the E‐spun NWNF mats, which were inserted into the interlaminar region of glass fiber reinforced epoxy laminates. The impact absorption energy, tensile strength, and flexural strength of the hybrid multiscale composites were found to increase with an increase in E‐spun NWNF mat weight fraction. These properties were compared to those of a conventional glass fiber composite laminates prepared from the neat epoxy resin with 32% glass fiber volume fraction. The effectiveness of the strengthening/toughening strategy formulated in this study indicates that the feasibility of using the E‐spun NWNF mat reinforcements for improving the mechanical properties of structured high‐performance composites. In addition, the present study provides motivation for the long‐term development of high‐strength high toughness bulk structural nanocomposites for broader engineering applications.
Nano-strengthened hybrid GRP composites were mechanically characterized for different multiwalled carbon nanotube (MWCNT) mass fractions of 0.1 wt%, 0.5 wt% and 1 wt% based on a 32 wt% glass fiber mass fraction. The selection of fabrication parameters for hybrid composites was based on tensile, flexural, and impact property results obtained from plain glass reinforced fiber composites (GRPs) by varying fiber mass fractions of 24 wt%, 32 wt% and 40 wt%. Results obtained indicated the 32 wt% as being the optimum mass fraction for the fabrication of GRP hybrid composite. For hybridization, functionalized multiwalled carbon nanotubes were selected as a secondary reinforcement and the optimum functionalization parameters were determined by considering three different functionalization times of 6 h, 24 h and 48 h respectively. The optimum functionalization time was then selected based on morphological characterization of functionalized MWCNTs which was performed using Raman, TEM and FTIR techniques. Based on the results obtained, the 24 h functionalization period on MWCNTs with nitric acid was found to be the most suitable. The final hybrid was then fabricated based on 32 wt% fiber fraction however with three different MWCNTs mass fractions for further characterization. The results obtained show that the nano-strengthened GRP hybrid composites reinforced with 0.5 wt% functionalized MWCNTs exhibit substantially better properties than those of plain GRP, 0.1 wt% and 1 wt% of functionalized MWCNT composites. At higher fiber mass fraction of 40%, the load transfer efficiency was reduced resulting in poor mechanical properties and similar behavior was also observed for hybrid composite with 1 wt% of CNTs. This anomalous behavior can be attributed to the poor quality of specimens due to fiber agglomerations in some places due to higher mass fraction which caused poor penetration of resin into the fiber mat resulting in inefficient load transfer.
