Carbon Nanotube Reinforced Supramolecular Hydrogels for Bioapplications

Nanocomposite hydrogels based on carbon nanotubes (CNTs) are known to possess remarkable stiffness, electrical, and thermal conductivity. However, they often make use of CNTs as fillers in covalently cross‐linked hydrogel networks or involve direct cross‐linking between CNTs and polymer chains, limiting processability properties. Herein, nanocomposite hydrogels are developed, in which CNTs are fillers in a physically cross‐linked hydrogel. Supramolecular nanocomposites are prepared at various CNT concentrations, ranging from 0.5 to 6 wt%. Incorporation of 3 wt% of CNTs leads to an increase of the material's toughness by over 80%, and it enhances electrical conductivity by 358%, compared to CNT‐free hydrogel. Meanwhile, the nanocomposite hydrogels maintain thixotropy and processability, typical of the parent hydrogel. The study also demonstrates that these materials display remarkable cytocompatibility and support cell growth and proliferation, while preserving their functional activities. These supramolecular nanocomposite hydrogels are therefore promising candidates for biomedical applications, in which both toughness and electrical conductivity are important parameters.     

Comparative study on the properties of poly(trimethylene terephthalate) ‐based nanocomposites containing multi‐walled carbon (MWCNT) and tungsten disulfide (INT‐WS2) nanotubes

Multi‐walled carbon (MWCNT) and tungsten disulfide (INT‐WS₂) nanotubes are materials with excellent mechanical properties, high electrical and thermal conductivity. These special properties make them excellent candidates for high strength and electrically conductive polymer nanocomposite applications. In this work, the possibility of the improvement of mechanical, thermal and electrical properties of poly(trimethylene terephthalate) (PTT) by the introduction of MWCNT and INT‐WS₂ nanotubes was investigated. The PTT nanocomposites with low loading of nanotubes were prepared by in situ polymerization method. Analysis of the nanocomposites' morphology carried out by SEM and TEM has confirmed that well‐dispersed nanotubes in the PTT matrix were obtained at low loading (<0.5 wt%). Thermal and thermo‐oxidative stability of nanocomposites was not affected by the presence of nanotubes in PTT matrix. Loading with INT‐WS₂ up to 0.5 wt% was insufficient to ensure electrical conductivity of PTT nanocomposite films. In the case of nanocomposites filled with MWCNT, it was found that nanotube incorporation leads to increase of electrical conductivity of PTT films by 10 orders of magnitude, approaching a value of 10^?3 S/cm at loading of 0.3 wt%. Tensile properties of amorphous and semicrystalline (annealed samples) nanocomposites were affected by the presence of nanotubes. Moreover, the increase in the brittleness of semicrystalline nanocomposites with the increase in MWCNT loading was observed, while the nanocomposites filled with INT‐WS₂ were less brittle than neat PTT. Copyright © 2016 John Wiley & Sons, Ltd.     

Poly(cetyl trimethylammonium 4-styrenesulfonate)-wrapped carbon nanotubes filled in polylactide nanocomposites: Fabrication and properties

Poly(cetyl trimethylammonium 4-styrenesulfonate) (PSS-CTA) was synthesized by the ionic exchange reaction of poly(sodium 4-styrenesulfonate) (PSS-Na) with cetyl trimethylammonium bromide (CTAB). It was then used as a surface modifier for carbon nanotubes (CNTs) to improve dispersion in and interfacial adhesion with a polylactide (PLA) matrix to fabricate high performance PLA/CNT nanocomposites via a solution precipitation method. The morphology, electrical conductivity, crystallization and mechanical properties of the PLA nanocomposites were investigated in detail. The results indicate that CNTs wrapped (coated) with a suitable amount of PSS-CTA dispersed in the PLA matrix homogeneously. The electrical conductivity of PLA was enhanced by up to 10 orders of magnitude with the incorporation of 1.0 wt% PSS-CTA-modified CNTs (mCNTs). The crystallization rate of PLA was improved due to the nucleation effect of mCNTs towards the crystallization of PLA, but the crystallization mechanisms and crystal structure of PLA remained unchanged with the incorporation of mCNTs. Both the tensile strength and toughness of PLA were improved by the incorporation of mCNTs, and the fracture behaviour of PLA changed from brittle e to ductile during tensile testing.     

Enhanced photocatalytic activity of mesoporous TiO2 aggregates by embedding carbon nanotubes as electron-transfer channel

Mesoporous multiwalled carbon nanotubes/titanium dioxide (CNTs/TiO(2)) nanocomposites with low loading amounts (0-0.5 wt%) of CNTs embedded inside mesoporous TiO(2) aggregates has been prepared by a simple one-pot hydrothermal method using titanium sulfate as titanium source. The as-prepared CNTs/TiO(2) samples are carefully characterized, analyzed and discussed. In contrast to previous reports with high CNT loading, our results indicate that a low CNT loading slightly influences the textural properties (including crystallite size, degree of crystallinity, specific surface areas, and pore volume etc.) and UV-light absorption of the mesoporous TiO(2) aggregates. The SEM and TEM results demonstrate that the CNTs are mostly embedded in the mesoporous TiO(2) aggregates. Moreover, chemical bonds are formed at the interface between CNTs and TiO(2), which is confirmed by the Raman, IR and XPS analyses. Significantly, we point out that PL analysis in terms of intensity of PL signals seems to not be a reliable way to monitor the recombination rate in the CNTs/TiO(2) composite, due to the quenching effect of CNTs. Instead, the analysis of transient photocurrent responses is introduced, which definitely reflects CNTs as fast electron transfer channels in chemically-bonded CNTs/TiO(2) composites with low CNT loading. Notably, the positive synergy effects of CNTs and TiO(2) depend on both the CNT loading amount and the state of interfacial contacts. In our study, only these chemically bonded CNTs/TiO(2) nanocomposites with appropriate loading amounts (<0.1 wt%) favor the separation of photogenerated electron-hole pairs and decrease their recombination rate and thus display significantly enhanced photocatalytic activity for degrading acetone in air under UV irradiation, as compared with pristine TiO(2) counterparts and commercial P25 photocatalyst. In contrast, a high CNT loading (>0.1 wt%) results in a decrease in photocatalytic activity; a simple mechanical mixing of CNTs and TiO(2) without forming chemical bonds at the interface also results in inferior photocatalytic performance.     

Electrical conductivities of carbon nanotube-filled polycarbonate/polyester blends

Carbon nanotube (CNT)-filled polycarbonate (PC)/poly(butylene terephthalate) (PBT) and polycarbonate (PC)/poly(ethylene terephthalate) (PET) blends containing 1 wt% CNTs over a wide range of blend compositions were prepared by melt mixing in a torque rheometer to investigate the structure-electrical conductivity relationship. Field emission scanning electron microscopy was used to observe the blend morphology and the distribution of CNTs. The latter was compared with the thermodynamic predictions through the calculation of wetting coefficients. It was found that CNTs are selectively localized in the polyester phase and conductive blends can be obtained over the whole composition range (20 wt%, 50 wt% and 80 wt% PBT) for CNT-filled PC/PBT blends, while conductive CNT-filled PC/PET blends can only be obtained when PET is the continuous phase (50 wt%, 80 wt% PET). The dramatic difference in the electrical conductivity between the two types of CNT-filled PC/polyester blends at a low polyester content (20 wt%) was explained by the size difference of the dispersed phases on the basis of the transmission electron microscope micrographs.     

Evident improvements in the rigidity,toughness, and electrical conductivity of PVDF/HDPE blend with selectively localized carbon nanotube

In this work, carbon nanotube (CNT) was used to fabricate poly(vinylidene fluoride) (PVDF)/high density polyethylene (HDPE) blend-based nanocomposites via a Haake mixer. Scanning electron microscopy confirmed that the CNT was mainly selectively located in the HDPE dispersed domains. Thermogravimetric analysis revealed that CNT addition improved the thermal stability of the blend (up to 61 °C increase at 3-phr CNT loading at 40 wt% loss) in air environment. Differential scanning calorimetry results revealed the enhanced nucleation of individual PVDF and HDPE upon crystallization in the composites; the presence of CNT inceased the stability of PVDF crystals. CNT addition increased the heat distortion temperature of the blend by up to 27 °C at 3-phr CNT loading. The complex viscosity and storage modulus increased due to the CNT pseudo-network formation in the reduce-sized HDPE phase of the composites. The rigidity of the blend was significantly improved after the addition of CNT. The impact strength of the blend increased by up to 66% after 2-phr CNT loading, and the electrical resistivity of the blend decreased by up to nine orders at 3-phr CNT loading due to the double percolation-like morphology formation.     

Thermal degradation and kinetic analysis of biodegradable PBS/multiwalled carbon nanotube nanocomposites

In this study, carbon nanotubes (CNTs) were first modified using N,N′‐ dicyclohexylcarbodiimide (DCC) dehydrating agents. Subsequently, the poly(butylene succinate)/multiwalled carbon nanotube (PBS/MWNTs) nanocomposites were prepared through facile melt blending. Thermal degradation of these PBS/MWNT nanocomposites was investigated; the kinetic parameters of degradation were calculated using the Coats and Redfern, Ozawa, and Horowitz and Metzger methods, respectively. It was found that the degradation reaction mechanism of PBS and the CNT‐C18 containing nanocomposites at lower temperature was likely to produce an F1 model through reaction of random chain cleavage (cis‐elimination). However, the reaction mechanism at higher temperature was likely to be a D1 model because of the dominant diffusion control effect. Moreover, it was found that the activation energies of CNT‐C18‐containing PBS nanocomposites were first increased with the content of CNT‐C18, but then decreased after the content was larger than 0.5 wt % for all models at differing heating rates. This may be due to the formation of a conductive network of CNTs in the polymer matrix at higher content of CNTs, which lead to better heat and electrical conductivity. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1231–1239, 2009     

An experimental investigation on the conductive behavior of carbon nanotube-reinforced natural polymer nanocomposites

It is well known that carbon nanotubes (CNTs) have excellent electrical properties and can be used as the nanofiller in natural polymers to produce conductive CNT/polymer nanocomposites. In this study, the conductive behavior of CNT-reinforced natural polymer nanocomposites was investigated. The effect of CNT concentration on the conductivity of CNT/natural polymer nanocomposites was also investigated. The natural polymers used were plasticized starch (PS) and chitosan (CS). FTIR spectroscopy was used to examine the interactions between PS, CS, and CNTs. TEM analysis on both nanocomposites were made to study the dispersion states of CNTs in both polymers. The results showed that the surface resistivities of both CNT/PS and CNT/CS nanocomposites decreased steeply with increasing CNT concentration. Particularly, the CNT/CS nanocomposites showed a better conductivity than the CNT/PS composites at the same CNT concentration. The TEM result showed that CNT/CS nanocomposites had better dispersibility and formation of fully connected, three-dimensional network structures between the CNTs than the CNT/PS nanocomposites, which results in the superior conductive property of CNT/CS nanocomposites compared to the CNT/PS nanocomposites.     

Functionalization of multi-walled carbon nanotubes by epoxide ring-opening polymerization

In this study, covalent functionalization of carbon nanotubes (CNTs) was accomplished by surface-initiated epoxide ring-opening polymerization. FT-IR spectra showed that polyether and epoxide group covalently attached to the sidewalls of CNTs. TGA results indicated that the polyether was successfully grown from the CNT surface, with the final products having a polymer weight percentage of ca. 14-74 wt%. The O/C ratio of CNTs increased significantly from 5.1% to 29.8% after surface functionalization of CNTs. SEM and TEM images of functionalized CNTs exhibited that the tubes were enwrapped by polymer chains with thickness of several nanometers, forming core-shell structures with CNTs at the center.     

Preparation and properties of chitosan nanocomposites with nanofillers of different dimensions

In this work, the chitosan ternary nanocomposites with two-dimensional (2D) clay platelets and one-dimensional (1D) CNTs have been successfully prepared by a simple solution-intercalation/mixing method in acid media. It was found that the thermal degradation temperature of chitosan (at 50% weight loss) could be only improved in about 20-30 °C by adding 3 wt% either clay or CNTs, however, almost 80 °C increase of degradation temperature could be achieved by adding 2 wt% clay and 1 wt% CNTs together. Dynamic mechanical measurement demonstrated an obviously improved storage modulus for chitosan/clay-CNTs than that for the corresponding binary chitosan/clay or chitosan/CNT nanocomposites with the same total filler content (3 wt%). For the solvent vapor permeation properties, a largely improved benzene vapor barrier property was observed only in chitosan/clay-CNT ternary nanocomposites and depended on the ratio of clay to CNTs. XRD, SEM and TEM results showed that both clay and CNTs could be well dispersed in the ternary nanocomposites with the nanotubes located around the clay platelets. FTIR showed an improved interaction between the fillers and chitosan by using both clay and CNTs. A much enhanced solid-like behavior was observed in the ternary nanocomposites, compared with the corresponding binary nanocomposites with the same total filler content, as indicated by rheological measurement. The unique synergistic effect of two-dimensional (2D) clay platelets and one-dimensional (1D) CNTs on the property enhancement could be tentatively understood as due to a formation of much jammed filler network with 1D CNTs and 2D clay platelets combined together. Our work demonstrates a good example for the preparation of high performance polymer nanocomposites by using nanofillers with different dimensions together.     

形状记忆聚偏氟乙烯/丙烯酸酯/碳纳米管纳米复合材料的导电及导热性能

利用聚偏氟乙烯（PVDF）微小结晶的物理交联点作用,制备了形状记忆性能优异的聚偏氟乙烯/丙烯酸酯聚合物（PVDF/ACM）共混材料,为提高其导电及导热性能,于其中引入了碳纳米管（CNT）,系统研究了PVDF/ACM/CNT三元体系纳米复合材料的导热及导电性能。 结果表明,碳纳米管在PVDF/ACM体系中分散均匀;在基本保持其形状记忆性能的前提下,碳纳米管的加入使材料导热性能及导电性能有较大程度的提高：质量分数为4%的CNT使材料25 ℃的电阻值降低至5000 Ω/square,导热系数提高至0.157 W/(m·K)。     

Improvement of electrical and material properties of epoxy resin/ aluminum nitride nanocomposites for packaging materials

This paper presents the influence of Aluminum Nitride (AlN) nanoparticles on the electrical and material properties of epoxy resin (EP). The EP/AlN nanocomposites with different concentrations of nano-AlN fillers are prepared. The dispersion of the nano-AlN particles in the composites is analyzed by a field emission scanning electron microscope (FESEM). The electrical properties are investigated by the space charge and DC conductivity measurements, whereas the material properties are studied by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. The results show that the homo-charge accumulation appears near both electrodes during the polarization, but there are limited negative charges left near both electrodes in the depolarization for the pure EP sample. There is no space charge accumulation in the 1 wt% and 2 wt% EP/AlN nanocomposites. The electric field distortion of the pure EP sample is 20%. Moreover, the electric field distortion initially decreases with the increase of the nano-AlN content, but it increases for the 2 wt% nano-AlN sample. Temperature has a dominant influence on the DC conductivity of the EP/AlN nanocomposites comparing to the pure EP. However, the DC conductivity of the nanocomposites becomes stable at high temperatures. It is also found that the weight loss of the samples decreases with the addition of the nano-AlN and the 1 wt% nano-AlN sample has the highest glass transition temperature. It is elucidated that the high apparent mobility and activation energy facilitate the space charge transport and suppressing the space charge accumulation. Furthermore, the nano-AlN filler can increase the trap level and trap energy density of the deep traps in the sample. The dielectric loss of the EP at high frequency is reduced with the content of 1 wt% nano-AlN. Furthermore, the addition of the nano-AlN can improve the thermal stability of the EP. The 1 wt% nano-AlN sample has the superior electrical insulation and material performance amongst the tested materials.     

Effect of temperature on AC conductivity of poly(butyl methacrylate)/cerium dioxide nanocomposites and applicability of different conductivity modeling studies

In this research, the effect of cerium dioxide (CeO₂) nanoparticles on electrical properties of poly(butyl methacrylate) (PBMA) has been investigated. Polymer nanocomposites reinforced with variable contents of CeO₂ nanoparticles (3, 5, 7 and 10 wt%) were fabricated by an in situ polymerization method. The formation of nanocomposites was analyzed by FTIR, XRD, SEM and TEM analysis. Also, the AC and DC conductivities of CeO₂ nanoparticles-reinforced PBMA were systematically studied with respect to different loadings of CeO₂ fillers. The FTIR, XRD and morphological studies revealed that the nanoparticles were well inserted and uniformly dispersed into the macromolecular chain of PBMA. The AC conductivity of PBMA/CeO₂ composite increases not only with the loading of nanoparticles but also with the temperature of the system. The activation energy determined from AC electrical conductivity was found to decrease with the frequency and temperature. DC conductivity of the nanocomposites was increased with the insertion of nanoparticles into PBMA. The DC conductivity of all the composites was greater than pure PBMA. The applicability of different theoretical models such as Scarisbrick, Bueche and McCullough equations was compared with the experimentally determined DC conductivity of PBMA/CeO₂ nanocomposites. These models fail to explain the conductivity of polymer composite in the entire loading of fillers. Hence, a new theoretical model is proposed in this study and it shows good agreement with the experimentally observed conductivity values.

     

Influence of MWCNT morphology on dispersion and thermal properties of polyethylene nanocomposites

In this study a series of multi-walled carbon nanotube (MWCNT)/Polyethylene (PE) composites with different kinds and several concentrations of carbon nanotubes (CNTs) were investigated. The morphology and degree of dispersion of the fillers in the polymer matrix at different length scales was investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Both individual and agglomerated MWCNTs were evident but a good dispersion was observed for some of them. TGA measurements were performed on nanocomposites in order to understand if CNTs affect the stabilization mechanism during thermal and oxidative degradation. The analysis demonstrates that MWCNTs presence slightly delays thermal volatilisation (15-20 °C) without modification of thermal degradation mechanism. In contrast, thermal oxidative degradation in air is delayed up to about 100 °C dependently from MWCNTs concentration, in the range used here (0.1-2.0 wt%), and degree of dispersion. The stabilization is due to the formation of a thin protective layer of entangled MWCNTs kept together by carbon char generated on the surface of the nanocomposites as shown by SEM images taken on degradation residues.     

Facile Fabrication of PBS/CNTs Nanocomposite Foam for Electromagnetic Interference Shielding

In order to reduce the pollutants of environment and electromagnetic waves, environment friendly polymer foams with outstanding electromagnetic interference shielding are imminently required. In this paper, a kind of electromagnetic shielding, biodegradable nanocomposite foam was fabricated by blending poly (butylene succinate) (PBS) with carbon nanotubes (CNTs) followed by foaming with supercritical CO₂. The crystallization temperature and melting temperature of PBS/CNTs nanocomposites with 4 wt % of CNTs increased remarkably by 6 °C and 3.1 °C compared with that of pure PBS and a double crystal melting peak of various PBS samples appeared in DSC curves. Increasing the CNT content from 0 to 4 wt % leads to an increase of approximately 3 orders of magnitude in storage modulus and nearly 9 orders of magnitude in enhancement of electrical properties. Furthermore, CNTs endowed PBS nanocomposite foam with adjustable electromagnetic interference (EMI) shielding property, giving a specific EMI shielding effectiveness of 28.5 dB cm³/g. This study provides a promising methodology for preparing biodegradable, lightweight PBS/CNTs foam with outstanding electromagnetic shielding properties.     

Synthesis,stereocomplex crystallization and properties of poly(l‐lactide)/four‐armed star poly(d‐lactide) functionalized carbon nanotubes nanocomposites

Functionalized carbon nanotubes (F‐CNTs) were synthesized through the nucleophilic substitution reaction between four‐armed star poly(d ‐lactide) (4PDLA) and acryl chloride of carbon nanotubes and were characterized using Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy and thermogravimetric analysis. The results indicated that the 4PDLA was successfully grafted onto carbon nanotubes, and it contained 45.5 wt% of 4PDLA. Poly(l ‐lactide) (PLLA) nanocomposites with different F‐CNTs content were prepared by solution casting. Optical microscopy and scanning electron microscopy results showed that F‐CNTs were uniformly dispersed in the nanocomposites. Crystallization behavior and crystal structure of PLLA nanocomposites were investigated using differential scanning calorimetry, polarizing microscope and X‐ray diffraction. The results found that poly(lactide) stereocomplex crystal could be formed between PLLA and F‐CNTs. F‐CNTs played different roles in the process of solution casting and melting crystallization. Polarizing microscope also revealed that crystallization temperature had a significant effect on the nucleation and spherulites growth of PLLA. Thermal stability and mechanical properties of the nanocomposites were also investigated by thermogravimetric analysis, dynamic mechanical analysis and tensile testing. These results demonstrated that the addition of F‐CNTs obviously improved thermal stability and tensile strength of PLLA. The results showed that PLLA/F‐CNTs would have potential values in engineering fields. Copyright © 2015 John Wiley & Sons, Ltd.     

Multiwalled carbon nanotubes reinforced poly (ether‐ketone) nanocomposites: Assessment of rheological,mechanical, and electromagnetic shielding properties

This study investigates the effect of multiwalled carbon nanotubes (MWCNTs) content on rheological, mechanical, and EMI shielding properties in Ka band (26.5‐40 GHz) of poly (ether‐ketone) [PEK] prepared by melt compounding using twin screw extruder. Transmission electron microscopy (TEM) and field emission gun scanning electron microscopy (FEG‐SEM) studies were adopted to identify dispersion of nanotubes in PEK matrix. TEM and SEM images showed uniform dispersion of MWCNTs in PEK/MWCNT composites even at loading of 5 wt%. The rheological studies showed that the material experiences viscous (fluid) to elastic (solid) transition at 1 wt% loading beyond which nanotubes form continuous network throughout the matrix which in turn promotes reinforcement. Additionally, Van‐Gurp Palmen plot (phase angle vs complex modulus) and values of damping factor further confirm that the material undergoes viscous to elastic transition at 1 wt% loading. This reinforcement effect of nanotubes is reflected in enhanced mechanical properties (flexural strength and flexural modulus). Flexural strength and flexural modulus of PEK showed an increment of 17% upon incorporation of 5 wt% of MWCNTs. Total shielding effectiveness (SE_T) of −38 dB with very high shielding effectiveness due to absorption (SE_A ~ −34 dB) was observed at 5 wt% loading of MWCNTs in PEK matrix in the frequency range of 26.5‐40 GHz (Ka band).     

聚乳酸/氧化锌柱撑皂石纳米复合材料制备与性能及结构表征

通过微波水解法制备了ZnO柱撑皂石,并以其为加工助剂制备了聚乳酸(PLA)/ZnO柱撑皂石纳米复合材料.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、对ZnO柱撑皂石及PLA/ZnO柱撑皂石纳米复合材料的结构进行了表征,并对其力学性能和热稳定性能进行了测试.微观结构分析表明,ZnO柱撑皂石呈现剥离状,并均匀分散在PLA基质中.力学性能研究表明0.3%ZnO柱撑皂石的加入有助于改善PLA复合材料的断裂伸长率.SEM分析表明PLA复合材料的断面发生明显改变,表现良好韧性;DSC结果显示纳米ZnO柱撑皂石可以降低复合材料的玻璃化转变温度、结晶温度,有助于提高PLA复合材料的结晶度,与XRD分析相吻合;热重分析表明ZnO柱撑皂石可以提高PLA复合材料的热稳定性.测试结果表明,ZnO柱撑皂石在PLA基质中起到了异相成核的作用,促进了PLA基质的结晶.     

Poly(vinylidene fluoride)/polyaniline/carbon nanotubes nanocomposites: Influence of preparation method and oscillatory shear on morphology and electrical conductivity

Nanocomposites of poly(vinylidene fluoride) (PVDF)/polyaniline (PAni)/carbon nanotubes (CNT) were prepared through melt blending using three different methods. The PVDF, CNT and PAni were added into the internal mixer at the same time in method I. In method II, PAni was polymerized in the presence of different amounts of CNT, and then added to PVDF. In method III, PAni was obtained with half the CNT content, and then added to PVDF with the other half of CNT. The morphology, rheological behavior and electrical conductivity of these systems were investigated through transmission electron microscopy (TEM) and combined electro-rheological measurements. As expected, the preparation method strongly influenced the final morphology of the nanocomposites, as shown by TEM analysis. The deformation and destruction of PAni-PAni and CNT-CNT bonds during the oscillatory shear experiments strongly affected the electrical conductivity, probably in two different ways: it breaks the PAni into smaller domains and also disrupts the CNT percolated network. Concluding, a good correlation between the electrical, flow behavior and preparation method could be achieved for PVDF/PAni/CNT nanocomposites, mainly by means of the combined electro-rheological measurements.     

Effect of dispersion and selective localization of carbon nanotubes on rheology and electrical conductivity of polyamide 6 (PA6), Polypropylene (PP), and PA6/PP nanocomposites

Nanocomposites were prepared by adding 1–3 vol % multiwalled carbon nanotubes (MWCNTs) to polyamide 6 (PA6), polypropylene (PP), and their co‐continuous blends of 60/40 and 50/50 volume compositions. Because of the good interaction and interfacial adhesion to the PA6, nanotubes were disentangled and distributed evenly through nanocomposites containing PA6. In contrast, lack of active interactions between the matrix and the CNTs resulted in poor tube dispersion in PP. These observations were then verified by studying the rheology and electrical conductivity of their respective nanocomposites. Absence of percolated CNT clusters and possible wrapping of the tubes by PA6 resulted in low electrical conductivity of PA6/CNT nanocomposites. On the other hand, despite the weak dispersion of the tubes, electrical conductivities of PP/CNT nanocomposites were much higher than all other counterparts. This could be the result of good three‐dimensional distribution of the agglomerated bundles and secondary aggregation of tubes in PP. Adding CNTs to blends of PA6/PP (60/40 and 50/50) resulted in almost full localization of carbon nanotubes in PA6, leading to their higher effective concentration. At the same CNT loadings, the blend nanocomposites had three to seven orders of magnitude higher electrical conductivity than pure PA6. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 368–378