Nanofillers In Polymer Matrix Research Articles

Exploration of third order nonlinear optical features of CuO/PVA-PEG polymer nanocomposites

CuO/PVA-PEG nanocomposites were prepared by solvent casting method. In XRD spectra, the shifting of peak position and the absence of remaining characteristics peaks of CuO nanoparticles in CuO/PVA-PEG indicates the formation exfoliated nanocomposites. The SEM image reveals the complete dispersion of the nanofillers in polymer matrix. FTIR spectra revealed the formation of strong H-bonds between PVA and PEG during mixing. The absorption and transmission properties of the sample were studied by UV-Vis studies. Z-scan analysis confirms the presence of two-photon absorption in the sample. The synthesized polymer nanocomposite exhibits optical nonlinearity due to the excitonexciton interaction.

Nanocomposites of PVA/chitosan blend with BiOCl:Eu3+ prepared by sonochemical route: Forensic and optoelectronics applications

Polymers of chitosan (CS) and polyvinyl alcohol (PVA) were combined effectively to create a synergetic property of both. To this composite, BiOCl:Eu3+ nanoparticles (NPs) were used as an appropriate filler. Vitamin B2 (VB2) was used as a biosafe coupling agent to modify the surface of NPs. Different weight percentage of BCE (50, 100, and 150 wt%) were then created using a casting/solvent evaporation process after being exposed to ultrasonic irradiations. The compatibility of NPs with the blend polymer were enhanced due to the coupling agent. Optical absorbance and thermal stability of compounds were impacted by inserting the modified NPs into the blend polymer. The hydrophilicity reduced for various ratios of the modified NPs loaded in the blend polymer, according to the contact angle measurements. The characteristic emission peaks of Eu3+ ions were observed at 581, 594, 621, 652, and 698 nm after being stimulated by 466 nm. With increased surface modifier concentration, the chromaticity diagram showed that emission colors altered from red to deep red. Reduced space charge polarization of the dipoles was shown to be the cause of the dielectric constant decreasing with frequency. The various resistive and capacitive elements of the produced materials are credited with the non-Debye type relaxation process. The level I-III ridge details are visible in the colorimetric images of fingerprints using the optimized nanofiller in polymer matrix on forensic-related surfaces. The aforementioned results made it abundantly evident that the improved NCs are very beneficial in multidimensional applications.

Microwave Attenuation Studies of Polypyrrole-SWCNT Nanocomposite Films for Improved EMI Shielding

In the process of finding stable, lightweight, broadband, cost-effective and improved electromagnetic interference (EMI) shielding material, electromagnetic wave attenuation properties of polypyrrole (PPy)—single-walled carbon nanotube (SWCNT) nanocomposite hybrid films were investigated in X-band region (8.2–12.4 GHz) and reported in the present work. The incorporation of SWCNT as a nanofiller in polymer matrix exhibits enhanced EMI shielding performance as compared to pure polymer films. The substantial values of dielectric loss with good impedance matching contribute to improvement in EMI shielding performance. It is found that with an increase of SWCNT loading in polymer matrix from 0 wt% to 5 wt%, nanocomposite films display a gradual increase in AC conductivity and total shielding effectiveness. The maximum total shielding effectiveness of 32.10 dB and minimum reflection loss of −45.54 dB with a wide bandwidth of 3.1 GHz, were obtained for 5 wt% CNT loading. The present results revealed that the prepared nanocomposite films are appropriate materials for lightweight, broadband EMI shields for radar and stealth applications.

Experimental Investigation into a New Method of scalable production of Reduced Graphene Oxide for potential industrial graphene nanocomposite manufacture

Graphene has attracted a great attention in the recent years of research innovations mainly due to its unique properties and in particular, its structural composition of one-atom thick sheet of hexagonally arrayed sp2 carbon atoms. This article focuses on a method of synthesis of graphene oxide granules, which can be use as nanofiller in polymer matrix. Polymer nanocomposites reinforced with graphene nanofillers have better mechanical, thermal and electrical properties than pure polymer materials. Some corrugated spherical structures/granules of reduced graphene oxide were produced by a dispersion/drying method. For this purpose the reduced graphene oxide suspension produced in the laboratory by an improved method was mixed on a magnetic stirring and delivered by a peristaltic pump to the granulation zone at a speed 10-20 ml/min. The granulation zone temperature was kept within 40-150°C. The suspension was dispersed by compressed air up to 3 atmospheres. The produced granules were accumulated in a receiver, and dried in the vacuum oven to remove residues of solvents used in the process. The engineered reduced Graphene oxide were analyzed and the material structural-morphology was characterized by XRD, TGA, UV, Raman and SEM.

TiO2 Containing Hybrid Composite Polymer Membranes for Vanadium Redox Flow Batteries.

In recent years, vanadium redox flow batteries (VRFB) have captured immense attraction in electrochemical energy storage systems due to their long cycle life, flexibility, high-energy efficiency, time, and reliability. In VRFB, polymer membranes play a significant role in transporting protons for current transmission and act as barriers between positive and negative electrodes/electrolytes. Commercial polymer membranes (such as Nafion) are the widely used IEM in VRFBs due to their outstanding chemical stability and proton conductivity. However, the membrane cost and increased vanadium ions permeability limit its commercial application. Therefore, various modified perfluorinated and non-perfluorinated membranes have been developed. This comprehensive review primarily focuses on recent developments of hybrid polymer composite membranes with inorganic TiO2 nanofillers for VRFB applications. Hence, various fabrications are performed in the membrane with TiO2 to alter their physicochemical properties for attaining perfect IEM. Additionally, embedding the -SO3H groups by sulfonation on the nanofiller surface enhances membrane proton conductivity and mechanical strength. Incorporating TiO2 and modified TiO2 (sTiO2, and organic silica modified TiO2) into Nafion and other non-perfluorinated membranes (sPEEK and sPI) has effectively influenced the polymer membrane properties for better VRFB performances. This review provides an overall spotlight on the impact of TiO2-based nanofillers in polymer matrix for VRFB applications.

A general strategy for fabricating polymer/nanofiller composite membranes with enhanced CO2/N2 separation performance

Aggregation of nanofillers, one of the critical challenges for developing high-performance composite membranes, induces non-selective gas transport paths, and thus reduces the gas separation selectivity. Here, we propose a facile and general filtration-spray strategy for fabricating polymer/nanofiller composite membranes to inhibit nanofiller aggregation. In this way, the nanofiller scaffold is first deposited on the surface of the porous substrate through filtration. Then, the polymer covers the scaffold via a spray method. Finally, a defect-free membrane is formed after penetration of polymer and thus filling of the inter-filler gaps during the solvent evaporation process. This strategy avoids redispersion and aggregation of nanofillers in polymer matrix, thus diminishing the non-selective defects of interparticles caused by nanofiller aggregation and forming dense polymer/nanofiller composite membranes with well-dispersed nanofillers. The as-prepared Pebax/PEI-ZIF-62 (polyethyleneimine functionalized ZIF-62) membrane exhibits an enhanced gas separation performance with a CO2 permeance of 58 GPU and a CO2/N2 selectivity of 83, which are 45% and 51% higher than those of the pure Pebax membrane, respectively, surpassing Robeson 2008 upper bound. However, the CO2 separation selectivity of PEI-ZIF-62@Pebax membrane prepared via spraying the mixed solution of Pebax and PEI-ZIF-62 decreases to 38, probably due to the formation of non-selective voids. To demonstrate the versatility of this facile strategy, various nanofillers, such as SiO2, ZIF-8, zeolite, and porous polymer sphere, have been used to prepare the composite membranes by this strategy, showing improved CO2 separation performance. Overall, these results demonstrate that the filtration-spray fabrication strategy is effective in preventing nanofiller aggregation in composite membranes.

Preferential alignment of two-dimensional montmorillonite in polyolefin elastomer tube via rotation extrusion featuring biaxial stress field

Preferential alignment of two-dimensional (2D) nanofillers in polymer matrix is essential to realize the transition of distinct properties from individual nanofiller into bulk nanocomposites, but this is an impossible task in conventional melt-processing because 2D nanofillers with two degrees of freedom experience transition and rotation movements along or around the two axes of the plate. Here, we proposed a flow manipulation strategy to control the preferential alignment of 2D montmorillonite (MMT) plates in polyolefin elastomer (POE) tube by superposing a hoop drag flow from rotation of mandrel and die onto axial flow caused by conventional extrusion. The biaxial stress field simultaneously restricted the axial and hoop rotation movements of the major and minor axes of the MMT plates, leading to preferential alignment along the hoop and longitudinal directions with the planar surface perpendicular to radial direction of the tube. As a result, the as-prepared tube exhibited strong resistance to various mechanical deformations (hoop kinking, axial and radial compression) as well as enhanced barrier property, holding the promising potential as an advanced tube in clinical interventional therapy and transportation of polar substances. Compared with the state-of-the-art techniques with complicated process and low productivity efficiency, this flow manipulation strategy for tailoring preferential alignment of 2D nanofillers was featured with a simple melt-processing, which was suitable for massive production and easily extended to the other composite tubes.

Gemini surfactant-assisted fabrication of graphene oxide/polyaniline towards high-performance waterborne anti-corrosive coating

Graphene oxide/polyaniline (GO/PANI) has been demonstrated to be an effective anti-corrosive nanofiller in polymer matrix, however, its hydrophobility restricts its application in waterborne polymer coatings. Here, cetyltrimethylammonium bromide (CTAB) and cationic gemini surfactant (GS) with the same constitutional unit as CTAB were adopted to fabricate CTAB modified GO/PANI (CGO/PANI) and GS modified GO/PANI (GGO/PANI). The incorporation of GS not only increased the intercalation degree of GO nanosheets but also functionalized as dopant to improve the electrochemical properties of PANI. The dispersibility and compatibility of GGO/PANI in waterborne alkyd resin (WAR) were also higher than that of CGO/PANI, resulting in the formation of more uniform nanocomposite coating. Compared with pure WAR, the coating resistance of GGO/PANI/WAR increased by 4 orders of magnitude, the corrosion density decreased by 3 orders of magnitude and the corrosion potential shifted from −0.72 V to −0.28 V. GGO/PANI/WAR also displayed enhanced long-term anti-corrosive properties in comparison with CGO/PANI/WAR.

The mechanism of reinforcement of nanocomposites polyurethane/graphene

The percolation model of reinforcement was used for the theoretical analysis of reinforcement mechanism for nanocomposites polyurethane/graphene. This model allows to elucidate influence of main factors (level of interfacial adhesion, nanofiller content, interfacial regions) on the degree of reinforcement or modulus of elasticity of the considered nanocomposites. It has been shown that for these nanocomposites actually nanofiller (graphene) serves as main reinforcing element. The sharp increasing of modulus of elasticity of nanocomposite occurs at achievement of critical content of nanofiller (∼9 % mas.). The same effect of increasing the level of interfacial adhesion is obtained by a polymer matrix-nanofiller, characterized by a transition from perfect adhesion to nanoadhesion. The structure type of nanofiller in polymer matrix (exfoliated or intercalated one) in one more factor. The proposed model is universal one for all nanocomposites polymer/2D-nanofiller.

Review of the past and recent developments in functionalization of graphene derivatives for reinforcement of polypropylene nanocomposites

AbstractGraphene has become the promising reinforcing candidate for improvement of polymer composites. However, graphene easily stacks into piles due to the presence of van der Waals forces between graphene layers and make it tremendously hard to be dispersed homogeneously in different polar polymer matrix. For years, some dispersion methods, such as chemical functionalization, melt mixing, solution mixing, in situ polymerization, to enhance the dispersion of nanofillers in polymer matrix have been demonstrated. Therefore, several functionalization methods of graphene, synthesis of composites approaches, characterizations techniques of graphene‐polypropylene composites are highlighted in this comprehensive review. This review also reveals that the addition of very low amount of nanofiller able to enhance the mechanical properties of composites considerably. With this review, a clear direction is beneficial for the researchers to solve the dispersion issues and to enhance interfacial adhesion to produce better mechanical properties of composites. The application of nanocomposite, an outlook of the challenges and different approaches that can practically useful to tackle important issues are also presented.

Условия получения высокомодульных нанокомпозитов полимер/углеродные нанотрубки

The physical basis of realization of high-modulus and high-strength nanocomposites polymer/carbon nanotube, having mechanical characteristics comparable with the same ones for steel, were considered. Two main factors, allowing to create such nanocomposites, were defined – the structure of nanofiller in polymer matrix and large enough content of nanofiller. The indicated structure fractal dimension should be close to dimension of surrounding Euclidean space, i.e. three one. Besides, elastic modulus of nanofiller depends on stiffness of polymer matrix. Therefore additional drawing of nanocomposite gives two positive effects: reduction of waviness of carbon nanotubes and enhancement of elastic modulus of polymer matrix owing to orientation of its macromolecules.

Morphology, Thermal Stability, and Flammability Properties of Polymer-Layered Double Hydroxide (LDH) Nanocomposites: A Review

The utilization of layered nanofillers in polymer matrix, as reinforcement, has attracted great interest in the 21st century. This can be attributed to the high aspect ratios of the nanofillers and the attendant substantial improvement in different properties (i.e., increased flammability resistance, improved modulus and impact strength, as well as improved barrier properties) of the resultant nanocomposite when compared to the neat polymer matrix. Amongst the well-known layered nanofillers, layered inorganic materials, in the form of LDHs, have been given the most attention. LDH nanofillers have been employed in different polymers due to their flexibility in chemical composition as well as an adjustable charge density, which permits numerous interactions with the host polymer matrices. One of the most important features of LDHs is their ability to act as flame-retardant materials because of their endothermic decomposition. This review paper gives detailed information on the: preparation methods, morphology, flammability, and barrier properties as well as thermal stability of LDH/polymer nanocomposites.

A novel bisection method based algorithm to quantify interphase in epoxy alumina nanocomposites

Polymer nanocomposites (PNCs) are emerging materials for the future due to their superior material characteristics with respect to base polymer and composites formed with traditional micro sized fillers. Researchers are concordant in attributing the improved properties of PNCs to large proportion of polymer-filler interaction zone (or an interphase). However, literature is indeed scanty to characterize interphase in terms of its size and properties. To come into possession of fine-tuned material properties through optimal use of naofillers, characterization of interphase is necessary. In this work, we propose a novel algorithm to characterize interphase in terms of its permittivity and thickness. Epoxy resin (LY556) is used as base polymer and aluminum oxide (Al2O3, average particle size = 50 nm) is used as filler material. Filler particles are surface treated using silane. Dispersion of nano filler in polymer matrix is verified using scanning electron microscopy (SEM). Dielectric spectroscopic measurements are carried out to measure permittivity over a frequency range of 10-2 to 107 Hz. A finite element based numerical model is developed to estimate effective permittivity of composites for different values of assumed interphase parameters (i.e. thickness and permittivity). Bisection method based algorithm is devised to assign actual thickness and permittivity to interphase based on the best fit of experimental and simulated results.

Local and Spatial Structure of Nanofiller in Polymer Matrix and Its Influence on the Properties of Nanocomposites

The structure of a nanofiller in a polymer matrix determines the properties of nanocomposites and a change in the type of structure from local to spatial; for example, formation of the percolation framework of particles (particle aggregates) of a nanofiller leads to a sharp deterioration in the properties of nanocomposites. Using the example of particulate-filled polymer/nanodiamond nanocomposites, it is shown that the transition from the standard mixing mode of a nanofiller with a polymer matrix melt in an extruder to mixing in the flow “breakdown” mode leads to a significant increase in the properties of nanocomposites. It is established that this effect is caused by a change in the type of structure of the nanofiller in the polymer matrix from a continuous spatial one (chain of nanofiller particles) to a local one (formation of individual clusters of nanoparticles). Within the framework of the fractal analysis, it is demonstrated that, when the type of structure changes from one-dimensional to two-dimensional, its fractal dimension changes from 1.18 to 1.75. The quantitative estimates of the degree of reinforcement of nanocomposites carried out within the percolation model with the established increase in the fractal dimension of the structure of the nanofiller are fully confirmed by experimental data. It is also shown that the elastic modulus of the nanofiller depends on the stiffness of the polymer matrix. The experimentally observed effect of dispersion of a nanofiller when mixing components in the “breakdown” mode is described in terms of the model of irreversible aggregation.

Synthesis and performance evaluation of nanocomposite soy protein isolate/carbon nanotube (SPI/CNTs) adhesive for wood applications

In this article, effect of the incorporation of carbon nanotubes (CNTs) into soy-based adhesive, obtained from soy protein isolate (SPI), on the performance of the nanocomposite adhesive is presented. Multifunctional and exceptional properties of carbon nanotubes (CNTs) in nanofiller in polymer matrix were explored in this study to develop nanocomposite soy-based adhesive with improved shear strength and water resistance. Consequently, nanocomposite SPI/CNT adhesives having different CNT loading were synthesized and evaluated. Morphology, thermal stability and chemical functionalities of the synthesized nanocomposite adhesives were checked using scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy, respectively. The bond strength test of the adhesives was carried out according to European standards, EN-204 and EN-205. The results showed that CNTs improved the shear strength of the nanocomposite SPI/CNT adhesive at reduced percentage loading. About 100% increase in the shear strength and water resistance was recorded for the nanocomposite SPI/CNTs adhesive when compared with an alkaline modified adhesive without carbon nanotubes. The shear strength of the nanocomposite adhesive increased from 3.48 MPa (adhesive without CNTs) to 6.91 MPa (adhesive with 0.3 wt% CNT loading) and then decreased afterwards as the CNT loading was increased beyond 0.3%. Enhanced shear strength of soy-based adhesives using different fillers has been reported in the literature, but at relatively high loading of the filler. In this study, relatively small amount of CNTs (0.3%) has shown a substantial enhancement in shear strength as compared to other fillers. It is expected that the newly developed adhesive could pave the way to solving the challenge of low shear bond strength and poor water resistance of soy-based adhesives for wood applications in the industry.

Preparation of highly thermally conductive and electrically insulating PI/BNNSs nanocomposites by hot-pressing self-assembled PI/BNNSs microspheres

Traditional polymer-based thermally conductive composites with randomly distributed fillers always yield an undesired heat removal due to the lack of efficient heat transfer pathways. Thus, realization of rational and ordered distribution of thermally conductive nanofillers in polymer matrix is believed to be significant for obtaining a desirable thermal conductivity. Herein, a series of thermally conductive polyimide/boron nitride nanosheets (PI/BNNSs) composites with a highly ordered BNNSs network have been successfully prepared. For achieving an uniform dispersion and high orientation of BN nanosheets in PI matrix, self-assembled PI/BNNSs complex microspheres were firstly prepared via the van der Waals interaction, and then these complex microspheres were further hot-pressed at the Tg of PI matrix, which rendered the alignment of BNNSs during the deformation of complex microspheres and built an efficient heat transfer pathway. As a consequence, the resultant composites possess a much higher in-plane thermal conductivity up to 4.25 W/mK with 12.4 vol% oriented BNNSs than those of pure PI and random distribution composite (0.85 W/mK for pure PI and 1.3 W/mK for the PI/random BNNSs-12.4). Meanwhile, these nanocomposites present excellent electrically insulating properties, improved dimensional stabilities and good thermal stabilities. This facile method provides a new way to design and fabricate highly thermally conductive PI-based composites for applying in heat dissipation of modern portable and collapsible electronic devices.

Сравнительный анализ эффективности углеродных нанотрубок и графена в армированнии полимерных нанокомпозитов

The comparative analysis of reinforcement efficiency (modulus of elasticity enhancement) of polymers with carbon nanotubes and grapheme was performed using the methods of fractal analysis and percolation theory. It has been shown that such comparison is correct only at the same structure of the indicated anisotropic nanofillers in polymer matrix. For carbon nanotubes reinforcement efficiency depends strongly on their geometry, i.e. length and outer diameter. In addition the main role in polymers reinforcement play not initial characteristics of nanofiller, but its structures, obtained in production process of nanocomposites. In technological aspect carbon nanotubes are more suitable for manufacture of high-modulus nanocomposites, that is due to possibility of simple enough realization of their orientation.

The effects of interfacial water and SiO2 surface wettability on the adhesion properties of SiO2 in epoxy nanocomposites

In moist environment, water absorption in inorganic nanofiller reinforced polymer nanocomposite is inevitable. However, little attention has been paid to study the effects of the absorbed water on the interfacial binding behavior of the inorganic nanofiller in polymer matrix. In this study, atomistic molecular dynamics simulations have been conducted to investigate the effects of the absorbed water on the interfacial binding behavior of silica nanoparticles (SiO2 NPs) in cross-linked epoxy nanocomposites (CENs). The results show that before water absorption, strong interfacial adhesion of hydrophilic SiO2 NPs in CENs is observed originated from the strong van der Waals (vdW), electrostatic and H-bonds interactions. However, after water absorption, water molecule will transport in CEN and be adsorbed at the interface between hydrophilic SiO2 NP and CEN. These adsorbed water will weaken the interfacial binding strength of the SiO2 in CEN. In contrast, for hydrophobic SiO2, weak interfacial adhesion is obtained before water absorption, while the decrease of the binding strength after water absorption is also restrained. This work provides a molecular-level understanding of the interfacial binding behavior of inorganic NPs in CENs, and the results give some principles to improve the binding strength of inorganic NPs in CENs.

Effect of nano-fillers on nonlinear conduction and DC breakdown characteristics of epoxy composites

In order to improve the nonlinear conduction ang dc breakdown strength, the influences of nano-fillers on epoxy nano-composites are studied. The epoxy nano-composites are prepared by regulating the shape factor of the semiconductor filling phase, with separate doping or two phase co-doping. The crystal structure and morphology of the composites and nano-fillers are analyzed by X ray diffraction and scanning electron microscopy. The conductivity and dc breakdown strength of the nano-composites are measured. The results show that the surface treated nano-fillers are well dispersed in the epoxy matrix. Compared with pure epoxy and epoxy nano-composites with lower filler loading of ZnO particles, the ones with higher filler loading of ZnO particles and lower filler loading of ZnO sheets exhibit a distinct nonlinear conduction character, but their breakdown strength is significantly reduced. By contrast, the breakdown strength of BN/epoxy nano-composites with low filler loading is significantly increased, and the 3 wt% BN/epoxy nano-composite behaves the highest breakdown strength. Based on 3 wt% BN nano-sheet, ZnO–BN epoxy nano-composites are prepared by two phase co-doping. Compared with single doping, the two phase co-doping nano-composites can not only improve the nonlinear conductivity, but also alleviate the problem of the serious deterioration of dc breakdown performance. The nonlinear conduction and dc breakdown properties of the studied nano-composites are related to the interaction zone of nano-filler in polymer matrix.

Локальная и пространственная структура нанонаполнителя в полимерной матрице и ее влияние на свойства нанокомпозитов

Локальная и пространственная структура нанонаполнителя в полимерной матрице и ее влияние на свойства нанокомпозитов