Carbon Nanotubes Based Polymer Nanocomposites Research Articles

Carbon nanotubes-based polymer nanocomposites: Bio-mimic preparation and methylene blue adsorption

The effective removal of environmental pollutants using nanomaterials and their composites has attracted great attention over the past few decades. Among them, carbon nanotubes (CNTs) have been extensively applied as adsorbents to remove various environmental pollutants for their small size, large surface areas and unique chemical structure. However, the adsorption performance of pristine CNTs is largely limited for their poor dispersibility and lack of functional groups. In this work, CNTs based composites (CNTs@poly(S-co-MA-DA)) have been successfully synthesized through combination of ring-opening reaction and mussel inspired chemistry. The pristine CNTs and as-prepared CNTs@poly(S-co-MA-DA) were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The influence of various experimental factors on the adsorption process, such as contact time, initial MB concentration, solution pH and temperature, was studied. Experimental results show that adsorption capacity of CNTs@poly(S-co-MA-DA) is about 4 times that of pristine CNTs in same experimental conditions. The kinetics and isotherms studies suggest that pseudo-second-order kinetic and Freundlich isotherm models could well fit with the adsorption data. The thermodynamic studies imply that the adsorption process of MB onto CNTs@poly(S-co-MA-DA) is endothermic and spontaneous. The adsorption mechanism might be the synergistic action of physical adsorption of CNTs@poly(S-co-MA-DA) particles and electrostatic interaction between the MB and functional groups on the surface of CNTs@poly(S-co-MA-DA) composites, including carboxyl, acylamino, hydroxyl and aromatic moieties. These obtained results and facts indicate that the as-prepared CNTs@poly(S-co-MA-DA) could be utilized as high-performance adsorbents with great potential applications in environmental treatment.

Thermal-air ageing treatment on mechanical, electrical, and electromagnetic interference shielding properties of lightweight carbon nanotube based polymer nanocomposites

Understanding the effect of thermal-air ageing treatment as well as concentration and dispersion of multiwall carbon nanotubes (MWCNT) in chlorinated polyethylene (CPE) system is very crucial for the development of a broad array of technological applications. This present work demonstrates an ultra-sonication assisted solution mixing strategy followed by hot compression for proper distribution of up to 15 wt% MWCNT within CPE matrix. Proper distribution of MWCNTs leads low percolation threshold (∼2.97 wt%) with high electrical conductivity value of 0.0035 S/cm and electromagnetic interference (EMI) shielding efficiency (36 dB) for 15 wt% MWCNT loading in the X-band frequency region (8.2–12.4 GHz). EMI shielding efficiency is discussed based on the nanofiller loading, thickness of material, after thermal-air ageing treatment, and repeated bending test. On account of thorough investigation, the proposed composites explore its emerging potential for making flexible and light weight EMI shields in vast areas from academic to industrial applications.

Evaluation of mechanical, thermal, electrical, and transport properties of MWCNT‐filled NR/NBR blend composites

Carbon nanotube based polymer nanocomposites found versatile applications and hence studying its reinforcing effect on NR/NBR blend system is a promising step in developing flexible elastomer gadgets. In this study, attempts have been made to prepare multi‐walled carbon nanotube (MWCNT)‐filled nanocomposites of NR/NBR blends. Raman spectra and transmission electron microscopic analysis indicate that there has been a finer and uniform dispersion of carbon nanotubes within the polymer matrix. Mechanical properties like tensile strength, tear resistance, abrasion loss and compression set of pure and blend samples showed an improvement with the increase in the dosage of MWCNT from 0.5 to 4 phr. 70/30 NR/NBR blend with 4 phr of MWCNT showed an improvement of 83% in tensile strength and 72% in tear strength compared to pure NBR. This is attributed to the uniform dispersion, high surface area, nano level interaction, and compatibility of MWCNT with the polymeric molecular chains. MWCNT is acting as a compatibilizing agent as is manifest from the increased negative values of free energy. Electrical conduction and thermal stability of the mixes were increased with the concentration of MWCNT due to the increase in the interfacial interaction resulting from the pi‐pi interaction with the nanotubes. POLYM. ENG. SCI., 58:961–972, 2018. © 2017 Society of Plastics Engineers

Multiscale modeling of electrical conductivity of carbon nanotubes based polymer nanocomposites

In this work, we applied multiscale modeling to investigate electrical conductivity of carbon nanotube (CNT) enhanced polymer composites. The multiscale approach is based on a combination of first-principles calculations of contact resistance between CNTs using Green's functions approach and statistical calculation of CNTs ensemble conductivity using the Monte Carlo percolation model. The results of first-principles calculations show strong dependence of contact resistance between CNTs on the angle φ between nanotubes axes: for (5,5) CNTs contact resistance increases by two orders of magnitude as φ changes from φ=0 to φ=π/4. This angular dependence of contact resistance has strong influence on conductivity of CNTs ensemble, decreasing composite conductivity by about an order of magnitude. We stress that obtained conductivity is the upper theoretical limit for an ideal CNT composite, and experimental data with larger values of conductivity should be attributed to positive influence of some non-idealities in composite.

Motion of carbon nanotubes based polymer nanocomposites subjected to multi-directional deformation

Interesting behavior is observed in the electrical resistance across the thickness of glass fibers/epoxy/carbon nanotubes (CNTs) laminate when the laminate is subjected to uniaxial stress along its length. Normally, when a tensile stress is applied along the length of the laminate, Poisson coupling would result in a decrease in the thickness of the laminate. One may expect that this would give rise to smaller electrical resistance across the thickness of the laminate due to the smaller dimension. However, the opposite is observed, ie., an increase in electrical resistance across the thickness. Additional experiments with loading along different directions were imposed on the laminate and electrical resistance was measured. An explanation is provided for this behavior. The results from these simple experiments and the proposed explanation can provide insight into the effect of the motion of the nanostructure on the macro electrical resistance behavior of polymer composite structures containing CNTs when the structure is subjected to multi-directional deformation.

Carbon nanotube based polymer nanocomposites: biomimic preparation and organic dye adsorption applications

Poly(sodium-p-styrene sulfonate) modified multi-walled carbon nanotubes (CNTs) have been prepared via a combination of mussel inspired chemistry and SET-LRP, and utilized for methylene blue removal with high efficiency.

Effective mechanical properties of nanocomposites reinforced with wavy carbon nanotubes

Carbon nanotubes (CNTs) possess exceptional mechanical properties and are therefore suitable reinforcements for composite materials. Nanotube efficiency in reinforcing the matrix depends on the CNT alignment, volume fraction and configuration, as well as matrix properties. In this investigation, finite element method (FEM) is used to investigate the effects of nanotube waviness ratio, volume fraction, and matrix modulus on properties of CNT based polymer nanocomposites. Nanocomposite mechanical properties are evaluated using a 3D nanoscale representative volume element. Models consisting of CNTs with different waviness ratios are created to investigate the effects of nanotube configuration on nanocomposite mechanical properties. Next, the effect of nanotube volume fraction on nanocomposite moduli of elasticity is investigated. Finally, the effects of matrix modulus are investigated by analysing models consisting of matrices with different moduli. The results of this investigation are compared with those found in the literature and good agreement is observed.