In this article, the interphase thickness in polymer carbon nanotubes (CNTs) nanocomposites (PCNT) is correlated to CNT radius and the extent of conductivity transportation from CNT to polymer matrix surrounding the CNT (K). In addition, CNT properties and “K” are applied to suggest the simple equations for percolation threshold and the fraction of networked CNT. A simple model is developed to predict the conductivity of PCNT assuming CNT size, “K” and tunneling resistance. The impacts of different parameters on the interphase thickness, percolation threshold, the fraction of networked CNT, and the conductivity of nanocomposites are studied and many experimental results are used to confirm the predictions. Thin and large CNT as well as high “K” cause low percolation threshold, large conductive networks and desirable conductivity in nanocomposites. Moreover, high tunneling resistivity and large tunneling distance negatively affect the conductivity, but the exceptional CNT conductivity is ineffective. The reasonable roles of all parameters in the predicted conductivity and the fine agreement between predictions and experimental results confirm the developed model. 相似文献
This article expresses a simple model for prediction of conductivity in polymer carbon nanotubes (CNT) nanocomposites (PCNT). This model suggests the roles of CNT concentration, CNT dimensions, CNT conductivity, the percentage of networked CNT, interphase thickness and tunneling properties in the conductivity of PCNT. The suggested model is applied to predict the conductivity in several samples. In addition, the significances of all parameters attributed to CNT, interphase and tunneling regions on the predicted conductivity are justified to confirm the suggested model. The calculations of conductivity properly agree with the experimental results demonstrating the capability of suggested model for prediction of conductivity. Thick interphase increases the conductivity of nanocomposites, because it enlarges the conductive networks. In addition, high tunneling resistivity due to polymer layer, large tunneling distance between adjacent CNT and small tunneling diameter deteriorate the conductivity, because they enhance the tunneling resistance limiting the charge transferring via tunneling regions. The suggested model can replace the available models to predict the conductivity in future researches. 相似文献
This article develops simple equations for tunneling distance between adjacent nanoparticles (d) and electrical conductivity of polymer/carbon nanotubes (CNT) nanocomposites (PCNT). The developed model considers the significances of CNT dimensions and waviness as well as interphase region surrounding CNT on the conductivity of nanocomposites. Moreover, d is defined by the sizes of CNT, interphase thickness and network density. The roles of all parameters for nanoparticles, interphase, percolation threshold and conductive network in the nanocomposite conductivity and tunneling distance are determined. Among the studied parameters, the fraction of percolated CNT of 0.6 and d = 1 nm provide the highest conductivity of PCNT, while d > 2.5 nm cause an insulated nanocomposite. In addition, the high concentration of thin CNT, a thick interphase, poor waviness, low percolation threshold, and the small fraction of percolated CNT produce an optimized level for d. 相似文献
Jang-Yin and Deng-Zheng equations for electrical conductivity of polymer carbon nanotubes (CNTs) nanocomposites (PCNT) are developed assuming the roles of networked CNTs, interphase, and tunneling regions. The developed models are coupled to formulate the operative resistance of a unit cell (Reff) induced by networked CNTs and tunneling region. The suggested equation is applied to calculate the operative resistance at dissimilar ranges of all parameters. In addition, the experimental measurements of conductivity for some samples are used to examine the predictability of the models. The models correctly predict the conductivity for various samples. Moreover, the parametric analyses demonstrate the sensible impacts of all parameters on the operative resistance justifying the suggested equation. A petite tunneling distance, wide tunnel, and poor polymer tunneling resistivity meaningfully deteriorate the operative resistance. 相似文献
The operative interphase properties surrounding carbon nanotubes (CNTs) networks are applied to progress a simple and applicable simulation for the strength of nanocomposites. Both critical interfacial shear strength (τc) and interfacial shear strength (τ) define the operative depth and power of interphase area. The experimental results of selected examples and the parametric analyses are employed to accept the established model. The experimental data properly fit to the model's forecasts and all parameters reasonably affect the nanocomposite's strength. Very low τc (10 MPa) and extremely high τ (400 MPa) significantly improve the strength of nanocomposites by 700%, while τc > 43 MPa slightly increase the nanocomposite's strength. The strongest and the densest interphase around CNT nets can raise the strength of nanocomposites by 450%, but very poor or thin interphase only changes the nanocomposite's strength by 10%. Additionally, the narrowest and the biggest CNT produce the sturdiest samples, while thick CNT (CNT radius > 11 nm) cannot strengthen the polymer media. 相似文献
In this work, we focus on the minimum interfacial shear modulus (Sc) and interfacial shear modulus (Si) controlling the efficiency of interphase zone in polymer clay nanocomposites, since the stress transferring through interphase section handles the stress bearing of samples. The roles of “Sc” and “Si” in the effective thickness and concentration of interphase zone are clarified. Moreover, a model based on Kolarik system is developed for modulus of clay-reinforced nanocomposites, which reflects the efficiency of interphase zone. The experimental data of tensile modulus for many samples display good matching with the predictions of the advanced model. Also, all model parameters properly manipulate the nanocomposite's modulus. Thick clay (t > 4 nm) cannot generate the interphase zone in the samples. A poor “Sc,” high “Si,” and thin clay improve the modulus of nanocomposites, but very high “Sc,” extremely poor “Si,” or thick clay cause a poor nanocomposite. A high value of Sc = 0.21 GPa deteriorates the reinforcing efficiency of clay in nanocomposites. Furthermore, low Si < 35 GPa produces a poorer nanocomposite than the polymer matrix. Additionally, complete exfoliation of thin clay (t = 1 nm) causes 900% improvement in the nanocomposite's modulus. 相似文献
In this work, we investigate the compatibilizing mechanism of nanoclay in binary polymer blends by measuring the interfacial tension of polystyrene/polyamide 6, PS/PA6, as a typical system, in the presence of nanoclay. The interfacial tension of PA6 nanocomposites and PS are determined with the breaking thread method by employing the Tomotika theory. The interfacial tension is reduced when organoclay is incorporated in the PA6 phase. To investigate the effect of the localization of nanoclay, nanoclay is intentionally located at the interface of PA6 and PS. Microscopic observations show that PA6 fiber remain unchanged and does not go through break-up process; therefore, one can deduce that the apparent interfacial tension of the system reduces significantly when nanoclay particles saturate the interface. 相似文献
The viscosity of immiscible polymer blends has been studied via application of certain aspects of rheology. A symmetric mixture rule was derived, and the deviations from the ‘additivity rule’ have been associated, essentially, with the properties of the interphase, with its influence on the effective volumes of the two polymers constituting the blend and with the deformability of both the interphase and the disperse phase. The rule predicts a positive deviation for a mixture with a disperse-phase viscosity (ηd) greater than that (ηm) of the continuous medium, and a much higher-viscosity interphase, i.e. ηi å ηd ≥ ηm. Negative deviation is to be expected when the interphase has a much lower viscosity than those of the two pure polymers (ηd, ηm å ηi) in the blend. The viscosity and strength of the interphase depend mostly on the specific thermodynamic interactions that led to its creation. 相似文献
This paper presents a comprehensive molecular dynamics study on the effects of the stoichiometric ratio of epoxy:hardener, hardener's linear and cyclic structure, and number of aromatic rings on the interfacial characteristics of graphene/epoxy nanocomposite. The van der Waals gap and polymer peak density as a function of the type of the hardener is calculated by analyzing the local mass density profile. Additionally, steered molecular dynamics are used to conduct normal pull-out of graphene to study the effect of the mentioned features of hardeners on the interfacial mechanical properties of nanocomposites, including traction force, separation distance, and distribution quality of reacted epoxide rings in the epoxy. Influence of the hardeners on the damage mechanism and its initiation point are also studied by analyzing the evolution of local mass density profile during the normal pull-out simulation. It is seen that stoichiometric ratio and geometrical structure of the hardeners affect the interfacial strength. It is also revealed that the hardener type can change the epoxy damage initiation point. The damage occurs in the interphase region for a higher stoichiometric ratio or cyclic structure of hardener. In comparison, for hardener's lower stoichiometric ratio and non-cyclic structure, failure begins in the epoxy near graphene layers. 相似文献
A two‐step method is suggested to predict the Young's modulus of polymer nanocomposites assuming the interphase between polymer matrix and nanoparticles. At first, nanoparticles and their surrounding interphase are assumed as effective particles with core–shell structure and their modulus is predicted. At the next step, the effective particles are taken into account as a dispersed phase in polymer matrix and the modulus of composites is calculated. The predictions of the two‐step method are compared with the experimental data in absence and presence of interphase and also, the influences of nanoparticles size as well as interphase thickness and modulus on the Young's modulus of nanocomposites are explored. The predictions of the suggested model show good agreement with the experimental data by proper ranges of interphase properties. Moreover, the interphase thickness and modulus straightly affect the modulus of nanocomposites. Also, smaller nanoparticles create a higher level of modulus for nanocomposites, due to the large surface area at interface and the strong interfacial interaction between polymer matrix and nanoparticles.
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