Zhang, X. Yi, H. Yui, S. Asai, and M. Sumita, Mater.
Yang and J. Liang, Appl.
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Xia, Y. Pan, L. Shen, and S. Xiao, J.
Pang, T. Chen, G. Zhang, B. Zeng, and Z. Li, Mater. Kabir-Ud-Din, U. Siddiqui, S. Kumar, and A. Dar, Colloid. Sohi, S. Bhadra, and D. Khastgir, Carbon 49, Received: 26 August Accepted: 3 September Related Papers. By Md. Mahbobor Rahaman. By Mostafizur Rahaman. Control of the temperature coefficient of the DC resistivity in polymer-based composites. Download pdf. Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link.
Need an account? After that, the curing agent was added to the mixtures at the 8. The edges of the samples were sandpapered in order to remove the top layer of the composite which might contain a bigger amount of polymer than the interior material. The microstructure of the composites and the morphology of the fillers were studied using Nova Nano SEM scanning electron microscope. The in-plane electrical conductivity measurement was carried out with AXB digital multimetre.
In order to minimize disturbances of the measurement, copper plate electrodes were attached to the edges of the samples with a constant pressure applied by tightening the clamping screws. The mechanical properties of the composites were investigated by three-point bending test in Zwick universal testing machine.
The obtained results were processed using testXpert II software provided by the manufacturer. SEM micrographs of milled secondary carbon fibres. XPS high-resolution spectra of sCF. More than twofold improvement was achieved as compared to the reference sample without nanofiller.
Mohd Radzuan group [ 10 ]. The increase in composites conductivity was related mainly to the dense packaging of fillers and better contact between the fibres due to MWCNTs filling in the spaces between sCF Fig. Such a hypothesis seems to be confirmed by the microstructure observations and high apparent density of samples.
Conductive Polymer Composites for
The improved density as well as the connections between the grains of conductive fillers made the electric current flow through the same cross section of composite with relatively lower losses, which resulted in the increased conductivity of composites. The reason for this drop was the increase in porosity and insufficient bonding of the composite by resin due to the excessive specific surface area of the nanofillers.
Therefore, the decrease in the resultant conductivity was directly caused by elongating the necessary path of the electric current and reducing the effective cross-sectional area of the porous conductor. Furthermore, comparably to the real solid, the porous materials are characterized by an effective cross-sectional area reduced by the area of pores cross section. Such a feature intensifies the electric current flow through a relatively narrower conductor and results in a correspondingly higher specific electrical resistivity of material [ 30 ].
The similar data were also observed by other researchers [ 10 ]. The most crucial factors to strengthen the epoxy composites are, inter alia, the interfacial adhesion, dispersion and shape of a filler and the mechanical properties of a matrix [ 31 ].
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The low viscosity of a binder and good wettability of a filler are both crucial factors to achieve good adhesion between individual phases in the case of hybrid composites with high loading of fillers. Having added nanofillers, the viscosity of a binder increases significantly, leading to a weaker binding of the material.
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Thus, in hybrid composites with high filler percentages, the final reinforcement is the combination of the dispersive strengthening due to the nanoparticle addition and general bonding of the material, which may be impaired by high viscosity of a binder. Graphene, as a material with outstanding electrical properties and the high aspect ratio, is being increasingly investigated as a conductive filler in CPC [ 32 ].
Such a high surface area requires a significant amount of low-viscosity binder with a suitable surface energy to wet the GN successfully [ 33 ]. The density measurements revealed deterioration of the overall composite binding, namely the porosity of all the samples was increasing along with the graphene content getting bigger.
Shape Memory Behavior of Conducting Polymer Nanocomposites | slicduclakors.cf
After the initial conductivity increase connected with the addition of high-conductive substance, the constant decrease in conductivity was noted, despite the increasing percentage of GN Fig. The solution to this problem may be a higher content of the binder characterized by lower viscosity. Another reason for the lack of improvement in electrical properties could be the insufficient dispersion of GN throughout the epoxy matrix. As shown in Fig. This behaviour probably resulted from the two competitive phenomena—dispersive matrix strengthening by GN and deterioration of overall composite bonding due to increased viscosity of epoxy resin.
Similar problems were reported by a number of other researchers [ 33 , 34 , 35 ]. The lowest flexural strength of the composite with 0. The mechanical mixing of EP with graphene could result in a poorer dispersion of nanoparticles and a lower increase in viscosity of the binder; therefore, this kind of composites is endowed with better mechanical properties. Small amounts of graphitized carbon black had a positive influence on conductivity of the hybrid CPC Fig. The initial increase in the electrical conductivity resulted mainly from the improved contact between fillers thanks to the presence of fine GCB.
This drop was caused by a weaker material bonding and probably a higher porosity of the composites with high loading of GCB. The conducted study proved the usefulness of the milled secondary carbon fibres as a primary filler in conductive hybrid polymer composites. Thanks to the incorporation of secondary nanofillers, it was possible to modify the electrical, mechanical and thermal properties of composites.
The MWCNTs turned out to be the most effective nanoadditive in terms of improving the electrical properties of hybrid systems. More than twofold increase in the electrical conductivity to The addition of graphene nanoplatelets caused a slight deterioration in the overall properties of the composites. That was a result of insufficient bonding of the composite caused indirectly by the excessive specific surface area of GNs. In the case of GCB, its small amounts had a positive impact on the electrical and mechanical properties of the investigated composites.
These results indicated that the recycled carbon fibres could be used as fillers to CPC and the addition of a small amount of carbon nanomaterials allows the creation of hybrid composites with potential applications in electromagnetic shielding, sensors, as conductive adhesive, etc. Skip to main content Skip to sections. Advertisement Hide.