scholarly journals Структурная трактовка изменения свойств нанокомпозитов полимер/углеродные нанотрубки у порога перколяции нанонаполнителя

2019 ◽  
Vol 89 (10) ◽  
pp. 1585
Author(s):  
Г.В. Козлов ◽  
И.В. Долбин
Keyword(s):  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Polymer Matrix ◽  
Fractal Analysis ◽  
Formation Process ◽  
Structural State ◽  
The Matrix ◽  
Carbon Nanotube Network ◽  
Degree Of Reinforcement ◽  
Aggregation Level

AbstractThe structure of the nanofiller in the polymer matrix of polymer/carbon nanotube nanocomposites can be characterized by the dimension of the nanofiller network, which is a direct indicator of its aggregation level. The formation process of such a network is considered as a result of interaction of the matrix polymer and a carbon nanotube; which allows us to determine its dimension with the help of fractal analysis. It is found that the dimension of the carbon nanotube network changes both qualitatively and quantitatively at their percolation threshold, reflecting different aggregation levels. This dimension uniquely determines the degree of reinforcement of such nanocomposites and their structural state as a system.

Critical Fiber Length for Load Transfer in Carbon Nanotube (CNT) Reinforced Composites

Aerospace ◽  
2004 ◽  
Author(s):  
Feridun Delale ◽  
Huapei Wan
Keyword(s):  
Carbon Nanotube ◽  
Polymer Matrix ◽  
Fiber Length ◽  
Strain Energy ◽  
Load Transfer ◽  
Effective Properties ◽  
Critical Length ◽  
Polymeric Composite ◽  
Effective Moduli ◽  
The Matrix

In this paper the load transfer mechanism in a carbon nanotube (CNT) reinforced polymeric composite is considered. It is assumed that the polymer matrix is reinforced with single-walled carbon nanotubes and that the continuum model with adjustments is valid in estimating the effective properties of the composite. The existing studies contradict each other with respect to effective load transfer between the matrix and the nanotubes. In this study we show that there is a critical CNT length below which the load transfer is not effective. Thus for an effective load transfer the CNT length must exceed a critical length. To determine the critical length we consider a CNT embedded in a polymer matrix. The polymer/CNT interface is modeled as a distinct layer with elastic properties different than those of the CNT and the matrix. The strain energy change due to the inclusion of a CNT in a polymer matrix is then computed for various interphase stiffnesses using the finite element method. The variation of the strain energy per unit fiber length ΔU/L is plotted versus the aspect ratio of the CNT, L/D. It is observed that ΔU/L first increases steeply with L/D and then reaches a plateau. Since the region of constant ΔU/L is associated with uniform stress distribution, we define the critical CNT length as 90% of the asymptotic value of ΔU/L. It is shown that the load transfer is affected by the nature of the interphase. Next, using a dilute solution the effective moduli of the composite are derived for the cases of both hard and soft interphase. The results indicate that the nature of matrix/CNT interface affects the effective moduli of the composite only slightly.

scholarly journals The structure of carbon nanotubes in a polymer matrix

2021 ◽  
Vol 23 (2) ◽  
pp. 223-228
Author(s):  
Georgii V. Kozlov ◽  
Gasan M. Magomedov ◽  
Gusein M. Magomedov ◽  
Igor V. Dolbin
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Polymer Matrix ◽  
Interfacial Layer ◽  
Glassy Matrix ◽  
Elastomeric Matrix ◽  
Strengthening Element ◽  
Form Ring ◽  
Nanofiller Content ◽  
Degree Of Reinforcement

We carried out an analytical structural analysis of interfacial effects and differences in the reinforcing ability of carbon nanotubes for polydicyclopentadiene/carbon nanotube nanocomposites with elastomeric and glassy matrices. In general, it showed that the reinforcing (strengthening) element of the structure of polymer nanocomposites is a combination of the nanofiller and interfacial regions. In the polymer matrix of the nanocomposite, carbon nanotubes form ring-like structures. Their radius depends heavily on the volume content of the nanofiller. Therefore, the structural reinforcing element of polymer/carbon nanotube nanocomposites can be considered as ring-like formations of carbon nanotubes coated with an interfacial layer. Their structure and properties differ from the characteristics of the bulk polymer matrix.According to this definition, the effective radius of the ring-like formations increases by the thickness of the interfacial layer. In turn, the level of interfacial adhesion between the polymer matrix and the nanofiller is uniquely determined by the radius of the specified carbon nanotube formations. For the considered nanocomposites, the elastomeric matrix has a higher degree of reinforcement compared to the glassy matrix, due to the thicker interfacial layer. It was shown that the ring-like nanotube formations could be successfully modelled as a structural analogue of macromolecular coils of branched polymers. This makes it possible to assess the effective (true) level of anisotropy of this nanofiller in the polymer matrixof the nanocomposite. When the nanofiller content is constant, this level, characterised by the aspect ratio of the nanotubes, uniquely determines the degree of reinforcement of the nanocomposites

scholarly journals Supramolecular ionic polymer/carbon nanotube composite hydrogels with enhanced electromechanical performance

2020 ◽  
Vol 9 (1) ◽  
pp. 478-488 ◽  
Author(s):  
Yun-Fei Zhang ◽  
Fei-Peng Du ◽  
Ling Chen ◽  
Ka-Wai Yeung ◽  
Yuqing Dong ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Ion Mobility ◽  
Artificial Muscles ◽  
Ionic Polymer ◽  
Composite Hydrogels ◽  
The Matrix ◽  
Electromechanical Performance ◽  
Carbon Nanotube Composite ◽  
Robotic Devices

AbstractElectroactive hydrogels have received increasing attention due to the possibility of being used in biomimetics, such as for soft robotics and artificial muscles. However, the applications are hindered by the poor mechanical properties and slow response time. To address these issues, in this study, supramolecular ionic polymer–carbon nanotube (SIPC) composite hydrogels were fabricated via in situ free radical polymerization. The polymer matrix consisted of carbon nanotubes (CNTs), styrene sulfonic sodium (SSNa), β-cyclodextrin (β-CD)-grafted acrylamide, and ferrocene (Fc)-grafted acrylamide, with the incorporation of SSNa serving as the ionic source. On applying an external voltage, the ions accumulate on one side of the matrix, leading to localized swelling and bending of the structure. Therefore, a controllable and reversible actuation can be achieved by changing the applied voltage. The tensile strength of the SIPC was improved by over 300%, from 12 to 49 kPa, due to the reinforcement effect of the CNTs and the supramolecular host–guest interactions between the β-CD and Fc moieties. The inclusion of CNTs not only improved the tensile properties but also enhanced the ion mobility, which lead to a faster electromechanical response. The presented electro-responsive composite hydrogel shows a high potential for the development of robotic devices and soft smart components for sensing and actuating applications.

scholarly journals A mechanism for fire retardancy realized by a combination of biofillers and ammonium polyphosphate in various polymer systems

Cellulose ◽  
2021 ◽  
Author(s):  
Koki Matsumoto ◽  
Tatsuya Tanaka ◽  
Masahiro Sasada ◽  
Noriyuki Sano ◽  
Kenta Masuyama
Keyword(s):  
Polymer Matrix ◽  
Synergetic Effect ◽  
Polymer System ◽  
Ammonium Polyphosphate ◽  
Fire Retardancy ◽  
Polymer Systems ◽  
Thermal Decomposition Behavior ◽  
Burning Behavior ◽  
The Matrix ◽  
Decomposition Behavior

AbstractThis study focused on realizing fire retardancy for polymer composites by using a cellulosic biofiller and ammonium polyphosphate (APP). The motivation of this study was based on revealing the mechanism of the synergetic effect of a cellulosic biofiller and APP and determining the parameters required for achieving a V-0 rating in UL94 standard regardless of the kind of polymer system used. As for the polymer matrix, polypropylene and polylactic acid were used. The flammability, burning behavior and thermal decomposition behavior of the composites were investigated through a burning test according to the UL-94 standard, cone calorimetric test and thermogravimetric analysis. As a result, the incorporation of a high amount of cellulose enabled a V-0 rating to be achieved with only a small amount of APP despite the variation of the optimum cellulose loading between the matrix polymers. Through analysis, the results indicated that APP decreased the dehydration temperature of cellulose. Furthermore, APP promoted the generation of enough water as a nonflammable gas and formed enough char until the degradation of the polymer matrix was complete. The conditions required to achieve the V-0 rating were suggested against composites incorporating APP and biofillers. Furthermore, the suggested conditions were validated by using polyoxymethylene as a highly flammable polymer.

Dual percolations of electrical conductivity and electromagnetic interference shielding in progressively agglomerated CNT/polymer nanocomposites

2021 ◽  
pp. 108128652110214
Author(s):  
Xiaodong Xia ◽  
George J. Weng
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Polymer Nanocomposites ◽  
Electromagnetic Interference ◽  
Effective Medium Theory ◽  
Scale Model ◽  
Shielding Effectiveness ◽  
Emi Shielding

Recent experiments have revealed two distinct percolation phenomena in carbon nanotube (CNT)/polymer nanocomposites: one is associated with the electrical conductivity and the other is with the electromagnetic interference (EMI) shielding. At present, however, no theories seem to exist that can simultaneously predict their percolation thresholds and the associated conductivity and EMI curves. In this work, we present an effective-medium theory with electrical and magnetic interface effects to calculate the overall conductivity of a generally agglomerated nanocomposite and invoke a solution to Maxwell’s equations to calculate the EMI shielding effectiveness. In this process, two complex quantities, the complex electrical conductivity and complex magnetic permeability, are adopted as the homogenization parameters, and a two-scale model with CNT-rich and CNT-poor regions is utilized to depict the progressive formation of CNT agglomeration. We demonstrated that there is indeed a clear existence of two separate percolative behaviors and showed that, consistent with the experimental data of poly-L-lactic acid (PLLA)/multi-walled carbon nanotube (MWCNT) nanocomposites, the electrical percolation threshold is lower than the EMI shielding percolation threshold. The predicted conductivity and EMI shielding curves are also in close agreement with experimental data. We further disclosed that the percolative behavior of EMI shielding in the overall CNT/polymer nanocomposite can be illustrated by the establishment of connective filler networks in the CNT-poor region. It is believed that the present research can provide directions for the design of CNT/polymer nanocomposites in the EMI shielding components.

scholarly journals Comparison of the Dielectric Properties of Ecoflex® with L,D-Poly(Lactic Acid) or Polycaprolactone in the Presence of SWCN or 5CB

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1719
Author(s):  
Patryk Fryń ◽  
Sebastian Lalik ◽  
Natalia Górska ◽  
Agnieszka Iwan ◽  
Monika Marzec
Keyword(s):  
Oleic Acid ◽  
Dielectric Properties ◽  
Polymer Matrix ◽  
Liquid Crystalline ◽  
Weight Ratio ◽  
Poly Lactic Acid ◽  
Relaxation Processes ◽  
The Matrix ◽  
Walled Carbon Nanotubes ◽  
Hybrid Layers

The main goal of this paper was to study the dielectric properties of hybrid binary and ternary composites based on biodegradable polymer Ecoflex®, single walled carbon nanotubes (SWCN), and liquid crystalline 4′-pentyl-4-biphenylcarbonitrile (5CB) compound. The obtained results were compared with other created analogically to Ecoflex®, hybrid layers based on biodegradable polymers such as L,D-polylactide (L,D-PLA) and polycaprolactone (PCL). Frequency domain dielectric spectroscopy (FDDS) results were analyzed taking into consideration the amount of SWCN, frequency, and temperature. For pure Ecoflex®, two relaxation processes (α and β) were identified. It was shown that the SWCN admixture (in the weight ratio 10:0.01) did not change the properties of the Ecoflex® layer, while in the case of PCL and L,D-PLA, the layers became conductive. The dielectric constant increased with an increase in the content of SWCN in the Ecoflex® matrix and the conductive behavior was not visible, even for the greatest concentration (10:0.06 weight ratio). In the case of the Ecoflex® polymer matrix, the conduction relaxation process at a frequency ca. several kilohertz appeared and became stronger with an increase in the SWCN admixture in the matrix. Addition of oleic acid to the polymer matrix had a smaller effect on the increase in the dielectric response than the addition of liquid crystal 5CB. Fourier transform infrared (FTIR) results revealed that the molecular structure and chemical character of the Ecoflex® and PCL matrixes remained unchanged upon the addition of SWCN or 5CB in a weight ratio of 10:0.01 and 10:1, respectively, while molecular interactions appeared between L,D-PLA and 5CB. Moreover, adding oleic acid to pure Ecoflex® as well as the binary and ternary hybrid layers with SWCN and/or 5CB in a weight ratio of Ecoflex®:oleic acid equal to 10:0.3 did not have an influence on the chemical bonding of these materials.

Single-walled carbon nanotube network/poly composite thin film for flow sensor

2010 ◽  
Vol 16 (6) ◽  
pp. 955-959 ◽  
Author(s):  
Hui Cao ◽  
Zhiyin Gan ◽  
Qiang Lv ◽  
Han Yan ◽  
Xiaobin Luo ◽  
...  
Keyword(s):  
Thin Film ◽  
Carbon Nanotube ◽  
Composite Thin Film ◽  
Flow Sensor ◽  
Single Walled Carbon Nanotube ◽  
Single Walled Carbon ◽  
Carbon Nanotube Network
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