Chemical surface coating of MWCNTs with riboflavin and its application for the production of poly(ester‐imide)/MWCNTs composites containing 4,4′‐thiobis(2‐tert‐butyl‐5‐methylphenol) linkages: Thermal and morphological properties

In this work, carboxylated multi‐walled carbon nanotubes (MWCNTs) were functionalized with riboflavin as a biological molecule under microwave irradiation. Solution blending method was used to incorporate different modified MWCNTs content (5, 10, and 15 wt %) into a chiral and biodegradable poly(ester‐imide) (PEI) to fabricate PEI‐based nanocomposites. The products were characterized for assessing the spectroscopic, thermal, and morphological properties by Fourier‐transform infrared spectroscopy, thermogravimetric analysis (TGA), X‐ray diffraction, transmission electron microscopy (TEM), and field‐emission scanning electron microscopy (FESEM). Optically active PEI was prepared by step‐growth polymerization of amino‐acid‐based diacid and aromatic diol. Functionalized MWCNTs were well dispersed in the PEI matrix and their distribution was homogeneous. This was confirmed by morphology study of the fractured surfaces of nanocomposites by FESEM and TEM. The addition of functionalized MWCNTs improved the thermal stability of NCs compared to the pure PEI. It was found from TGA data that temperature at 10% weight loss was increased from 409°C for pure PEI to 417, 420, and 424°C for nanocomposites containing 5, 10, and 15% functionalized MWCNTs, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42908.     

Efficient functionalization of multi‐walled carbon nanotubes with p‐aminophenol and their application in the fabrication of poly(amide‐imide)‐matrix composites

The ultrasonically assisted preparation and characterization of poly(amide‐imide) (PAI) composites containing functionalized multi‐walled carbon nanotubes (MWCNTs) are reported. To improve the dispersion in and compatibility with the polymer matrix, the MWCNTs were surface‐modified with p‐aminophenol (p‐AP) under microwave irradiation. The process is fast, one‐pot, easy and results in a high degree of functionalization as well as dispersibility in organic solvents. The p‐AP‐functionalized MWCNTs (MWCNTs‐AP) were analysed by means of field emission and transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction and thermogravimetric analysis (TGA). The results consistently confirm the formation of p‐AP functionalities on MWCNTs which are able to undergo additional reactions, while the structure of the MWCNTs remains relatively intact. MWCNTs‐AP/PAI hybrid films were prepared with various MWCNTs‐AP contents (5–15 wt%) using a solution‐casting technique. Microscopic observations show that the dispersion of the MWCNTs‐AP is improved as a result of the organic groups on the MWCNT surface and functional groups in the PAI structure. The properties of the obtained composites were characterized extensively using the aforementioned techniques. TGA results show that the hybrid films exhibit a good thermal stability. Tensile mechanical testing was performed for the prepared composites, the results of which indicate an increase in the elastic modulus and tensile strength with increasing MWCNTs‐AP content. © 2013 Society of Chemical Industry     

Polyethylenimine‐functionalized multiwalled carbon nanotube for the adsorption of hydrogen sulfide

Functionalized multiwalled carbon nanotubes (MWCNTs) were synthesized with ethane diamine and polyethylenimine (PEI) with molecular weights of 1800 [MWCNT‐PEI weight‐average molecular weight (M_w) = 1800] and 70,000 (MWCNT‐PEI M_w = 70,000), respectively. The structures and properties of the ethane diamine functionalized MWCNTs and PEI‐functionalized MWCNTs were characterized by Raman spectroscopy, thermogravimetric analysis, X‐ray powder diffraction, and scanning electron microscopy. An increase with the D/G (D, Disorder band; G, Graphite) ratio of the functionalized MWCNTs in the Raman spectra proved that the ethane diamine and PEI were successfully bonded to the surface of the pristine MWCNTs. The results of TGA also confirmed this. In addition, the structure of the functionalized MWCNTs showed no significant changes compared with the pristine MWCNTs; this was confirmed by X‐ray powder diffraction. Hydrogen sulfide (H₂S) sorption on the functionalized MWCNTs was studied by UV spectroscopy. As expected, the results of UV spectroscopy shows that the MWCNTs bonded with higher molecular weight PEI had a more excellent H₂S adsorption efficiency than those bonded with low‐molecular‐weight PEI and ethane diamine, a micromolecular amine. The effects of the pH and temperature on the adsorption of H₂S were also studied. Under the conditions investigated, the maximum first‐time H₂S adsorption efficiency of 1.94 mmol/g was observed for MWCNT‐PEI (M_w = 70,000) in the 60 mg/L sodium hydrosulfide (NaHS) aqueous solution. In addition, the H₂S reversible adsorption of the functionalized MWCNTs was conducted, and the second‐time H₂S adsorption efficiency of MWCNT‐PEI (M_w = 70,000) reached 1.83 mmol/g in the 60 mg/L NaHS aqueous solution. The results demonstrate that the MWCNTs decorated with high‐molecular‐weight PEI were potentially excellent and reversible H₂S adsorbents. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44742.     

Ultrasonic assisted organo-modification of mesoporous SBA-15 with N-trimellitylimido-l-methionine and preparation of the poly(amide–imide)/SBA nanocomposites

Mesoporous SBA-15 materials were functionalized with N-trimellitylimido-l-methionine through ultrasonic irradiation, and the resulting functionalized materials were investigated as reinforcing agent for the preparation of the polymer based nanocomposites (NCs). An optically active and organo-soluble l-methionine containing poly(amide–imide) (PAI) was synthesized by the direct step-growth polymerization reaction of the above chiral diacid and 3,5-diamino-N-(pyridin-3-yl) benzamide in molten tetrabutylammonium bromide as a green solvent. A simple solution blending process was used to efficiently disperse modified-SBA into the chiral PAI to obtain PAI/modified-SBA NCs. The obtained NCs were characterized by Fourier transform-infrared spectroscopy, thermogravimetry analysis (TGA), X-ray diffraction, field emission-scanning electron microscopy, and transmission electron microscopy (TEM) techniques. TGA data indicated an increasing in thermal stability of the NCs when compared to the pure polymer. TEM images show well-ordered hexagonal arrays of mesopores SBA and the average distances between neighboring pores is around 3–5 nm.     

Preparation and characterization of multi‐walled carbon nanotube/poly(ethylene terephthalate) nanoweb

Multi‐walled carbon nanotube (MWCNT)/Poly(ethylene terephthalate) (PET) nanowebs were obtained by electrospinning. For uniform dispersion of MWCNTs in PET solution, MWCNTs were functionalized by acid treatment. Introduction of carboxyl groups onto the surface of MWCNTs was examined by Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) analysis. MWCNTs were added into 22 wt % PET solution in the ratio of 1, 2, 3 wt % to PET. The morphology of MWCNT/PET nanoweb was observed using field emission‐scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM). The nanofiber diameter decreased with increasing MWCNT concentration. The distribution of the nanofiber diameters showed a bi‐modal shape when MWCNTs were added. Thermal and tensile properties of electrospun MWCNT/PET nanowebs were examined using a differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), dynamic mechanical analyzer (DMA) and etc. Tensile strength, tensile modulus, thermal stability, and the degree of crystallinity increased with increasing MWCNT concentration. In contrast, elongation at break and cold crystallization temperature showed a contrary tendency. Electric conductivities of the MWCNT/PET nanowebs were in the electrostatic dissipation range. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel nanocomposites obtained by dispersion of LDH modified with N‐tetrabromophthaloyl‐glutamic in poly(amide‐imide) having N‐trimellitylimido‐l‐leucine and 4,4′‐diaminodiphenylether units

Layered double hydroxides (LDHs) have attracted much attention as nanofillers in polymer nanocomposites (NCs) due to their particular surface structural, positively charged layer and so on. In this study, a chiral diacid was synthesized by the reaction of tetrabromophthalic anhydride and glutamic acid. LDH was modified by co‐precipitation of aluminum nitrate, magnesium nitrate, and glutamic acid containing diacid. Chiral poly(amide‐imide) (PAI) was synthesized by direct polycondensation reaction of N‐trimellitylimido‐l ‐leucine and 4,4′‐diaminodiphenylether. Different NCs of the obtained modified LDHs and the chiral PAI were prepared in a short time using ultrasonic technique. The morphology and the structure of the obtained samples were characterized by Fourier transform infrared, thermogravimetric analysis (TGA), field emission scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction analysis. TGA of the NCs showed a special order in thermal stability in compression with the neat PAI owing to the uniform distribution of the nanofillers. POLYM. COMPOS., 37:1323–1329, 2016. © 2014 Society of Plastics Engineers     

Improving thermal conductivity and shear strength of carbon nanotubes/epoxy composites via thiol‐ene click reaction

This study investigates the effect of the thiol‐ene click reaction on thermal conductivity and shear strength of the epoxy composites reinforced by various silane‐functionalized hybrids of sulfhydryl‐grafted multi‐walled carbon nanotubes (SH‐MWCNTs) and vinyl‐grafted MWCNTs (CC‐MWCNTs). The results of Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermal gravimetric analysis (TGA), and transmission electron microscopy (TEM) show that the sulfhydryl groups and vinyl groups are successfully grafted onto the surface of MWCNTs, after treatment of MWCNT with triethoxyvinylsilane and 3‐mercaptopropyltrimethoxysilane, respectively. Scanning electron microscopy (SEM), HotDisk thermal constant analyzer (HotDisk), optical microscope, and differential scanning calorimetry (DSC) are used to characterize the resultant composites. It is demonstrated that the hybrid of 75 wt % SH‐MWCNTs and 25 wt % CC‐MWCNTs has better dispersion and stability in epoxy matrix, and shows a stronger synergistic effect in improving the thermal conductivity of epoxy composite via the thiol‐ene click reaction with 2,2′‐azobis(2‐methylpropionitrile) as thermal initiator. Furthermore, the tensile shear strength results of MWCNT/epoxy composites and the optical microscopy photographs of shear failure section indicate that the composite with the hybrid MWCNTs has higher shear strength than that with raw MWCNTs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44579.     

The thermal,optical, flame retardant,and morphological consequence of embedding diacid‐capped ZnO into the recycled PET matrix

We extended our work to a fast and facile nanocomposites (NCs) manufacturing by incorporation of ZnO nanoparticles (NPs) on to a recycled poly(ethylene terephthalate) PET as a polymer matrix prepared by a dissolution/reprecipitation method. The surface of ZnO NPs was functionalized with synthesized optically active diacid containing alanine amino acid. Organo‐modified NPs which provided using solution blending technique through ultrasonic irradiation, were embedded into recycled PET. PET@ZnO/DA NCs containing different loadings of functionalized NPs (1, 3, 5 wt %) were investigated by thermal gravimetric analysis, field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy and UV–visible spectroscopy. Morphological studies revealed uniformly dispersed ZnO/DA NPs in the polymer matrix. The crystalline nature of PET slightly improved as a function of the NPs concentration. Char yield in TGA and LOI values indicated that the obtained NCs were capable of exhibiting flame retardant properties. The NCs were found to exhibit more absorbance in the UV and visible region in compare to the neat PET. The effect of ultrasonication in different solvent on the morphology of the recycled polymer particle was also studied. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43433.     

Amino functionalization of multiwalled carbon nanotubes by gamma ray irradiation and its epoxy composites

In this paper, γ‐ray radiation technique was utilized to simply functionalize multi‐walled carbon nanotube (MWCNT) with amino groups. The successful amino functionalization of MWCNTs (MWCNTs‐Am) was proven and the physicochemical properties of MWCNTs before and after radiation grafting modifications were characterized using FT‐IR, X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results indicated that the γ‐ray radiation had the visible effects on the surface properties of MWCNTs. The effects of various functionalized MWCNTs on morphological, thermal, and mechanical properties of an epoxy‐based nanocomposite system were investigated. Utilizing in situ polymerization, 1 wt% loading of MWCNT was used to prepare epoxy‐based nanocomposites. Compared to the neat epoxy system, nanocomposites prepared with MWCNT‐Am showed 13.0% increase in tensile strength, 20.0% increase in tensile modulus, and 24.1% increase in thermal decomposition temperature. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Investigation on production and characterization of bionanocomposites based on surface functionalized multi-walled carbon nanotubes and optically active poly(ester-imide) having L-isoleucine units

Carboxylic functionalized multi-walled carbon nanotubes (MWCNTs) have been incorporated to biodegradable poly(ester-imide) (PEI) matrix and the effect of the carboxylated-MWCNT on the thermal and morphological properties of MWCNT-reinforced bionanocomposites (BNCs) was demonstrated. Chiral PEI was synthesized from a step-growth polymerization of amino acid based diacid (4) with 4,4′-thiobis(2-tert-butyl-5-methylphenol) (5) promoted by tosyl chloride in pyridine and N,N-dimethyl formamide solution. The resulting BNCs were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The homogeneous dispersion of MWCNTs throughout PEI matrix and strong interfacial adhesion between them were achieved in the obtained BNCs as evidenced by FE-SEM and TEM images. The results from TGA indicated that the thermal stability of the resulting BNCs was obviously improved in comparison with the pure PEI.     

Preparation,morphological and thermal characterization of novel nanocomposites based on poly (amide-ester-imide) containing amino acid and nano-Mg-doped fluorapatite surface modified with biodegradable diacid N-trimellitylimido-L-leucine

In this investigation, we prepared novel nanocomposites (NC) s based on poly (amide-ester-imide) (PAEI) containing L-leucine moiety and surface modified nano-Mg-doped fluorapatite (Mod-MgFA) with biodegradable diacid, via ultrasound irradiation. First, surface of nanocystalline Mg-doped fluorapatite was functionalized with biodegradable optically active diacid N-trimellitylimido-L-leucine (TML) by ultrasonic irradiation, so as to increase the compatibility and dispersity in the PAEI matrix. After modification via diacid TML, the Mg-doped fluorapatite was altered from a hydrophilic state to an organophilic one. At that time, the obtained functionalized Mod-MgFA was investigated as reinforcing agent for the synthesis of the PAEI NCs. The resulting NCs were characterized by Fourier transform infrared (FT-IR), transmission electron microscopy, field emission-scanning electron microscopy (FE-SEM), X-ray diffraction, and thermogravimetric analysis (TGA) techniques. TGA data showed an increasing in thermal stability of the aforementioned NCs when compared to the neat PAEI. FE-SEM results presented a rather good amount of dispersion of Mod-MgFA in the polymer matrix.     

Synthesis and characterization of LiFePO4–carbon nanofiber–carbon nanotube composites prepared by electrospinning and thermal treatment as a cathode material for lithium‐ion batteries

Binder‐free LiFePO₄–carbon nanofiber (CNF)–multiwalled carbon nanotube (MWCNT) composites were prepared by electrospinning and thermal treatment to form a freestanding conductive web that could be used directly as a battery cathode without addition of a conductive material and polymer binder. The thermal decomposition behavior of the electrospun LiFePO₄ precursor–polyacrylonitrile (PAN) and LiFePO₄ precursor–PAN–MWCNT composites before and after stabilization were studied with thermogravimetric analysis (TGA)/differential scanning calorimetry and TGA/differential thermal analysis, respectively. The structure, morphology, and carbon content of the LiFePO₄–CNF and LiFePO₄–CNF–MWCNT composites were determined by X‐ray diffraction, high‐resolution transmission electron microscopy, Raman spectroscopy, scanning electron microscopy, and elemental analysis. The electrochemical properties of the LiFePO₄–CNF and LiFePO₄–CNF–MWCNT composite cathodes were measured by charge–discharge tests and electrochemical impedance spectroscopy. The synthesized composites with MWCNTs exhibited better rate performances and more stable cycle performances than the LiFePO₄–CNF composites; this was due to the increase in electron transfer and lithium‐ion diffusion within the composites loaded with MWCNTs. The composites containing 0.15 wt % MWCNTs delivered a proper initial discharge capacity of 156.7 mA h g^?1 at 0.5 C rate and a stable cycle ability on the basis of the weight of the active material, LiFePO₄. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43001.     

Microwave‐assisted synthesis and characterization of polyimide/functionalized MWCNT nanocomposites containing quinolyl moiety

Polyimide‐MWCNT nanocomposites were prepared by the reaction of a heterocyclic diamine monomer of bis(4‐amino‐3,5‐dimethylphenyl)‐2‐chloro‐3‐quinolylmethane (BACQM), pyromellitic dianhydride (PMDA) with unmodified MWCNT (MWCNT), acid‐functionalized MWCNT (acid‐MWCNT) or amine‐functionalized MWCNT (amine‐MWCNT) using microwave irradiation as well as by the conventional method. The structure of the monomer was confirmed by FTIR, ¹H‐NMR, and ¹³C‐NMR spectral techniques. The glass transition temperature (T_g) of the MWCNTs/polyimide nanocomposite was found to be higher than that of the unfilled polyimide system. The T_g's of both systems were higher when prepared with the microwave method than the conventional synthesis. The T_g's of the nanocomposites using acid and amine functionalized MWCNTs are greater than 300°C, in both methods. This is attributed to the presence of hydrogen bond and strong covalent bond in both the acid‐MWCNT/polyimide and amine‐MWCNT/polyimide systems. The morphological studies of the nanocomposites synthesized using microwave irradiation show that a distinct MWCNT nanofibrillar network is formed in the matrix when MWCNT or acid‐MWCNT is used. A homogeneous morphology, without distinct nanotube domains is seen when the amine‐MWCNT is covalently linked to the polymer. POLYM. COMPOS., 37:2417–2424, 2016. © 2015 Society of Plastics Engineers     

Conducting epoxy networks modified with non‐covalently functionalized multi‐walled carbon nanotube with imidazolium‐based ionic liquid

Multi‐walled carbon nanotube (MWCNT) was non‐covalently functionalized with room‐temperature ionic liquid (IL), 1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate and blended with epoxy pre‐polymer (ER) with the assistance of ultrasonication in the presence of acetone as a diluting medium. The ability of IL in improving the dispersion of MWCNT in epoxy pre‐polymer was evidenced by transmission optical microscopy. The corresponding epoxy/MWCNT networks cured with anhydride displayed an increase of the electrical conductivity of around three orders of magnitude with the addition of IL in a proportion of MWCNT/IL = 1:5 mass ratio. The effect of IL on dynamic mechanical properties and thermal conductivity was also evaluated. The improved thermal and electrical properties was attributed to the better dispersion of MWCNT within the epoxy matrix by IL, evidenced by transmission electron microscopy of the ER/MWCNT networks cured with anhydride. Raman spectroscopy was also used to confirm the interaction between MWCNT and IL. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43976.     

Properties of surface‐modified multiwalled carbon nanotube filled poly(ethylene terephthalate) composite films

Poly(ethylene terephthalate) (PET)/multiwalled carbon nanotube (MWCNT) composites were prepared by in situ polymerization. To improve the dispersion of MWCNTs in the PET matrix, functionalized MWCNTs having acid groups (acid‐MWCNTs) and acetic groups (acetic‐MWCNTs) on their surfaces were used. The functional groups were confirmed by infrared spectrometry. Scanning electron microscopy showed that acetic‐MWCNTs had a better dispersion in the PET matrix than pristine MWCNTs and acid‐MWCNTs. A reaction between PET and acetic‐MWCNTs was confirmed by a shift of the Raman G band to a higher frequency and an increase of the complex viscosity in the rheological properties. The composites containing functionalized MWCNTs showed a large increase in their tensile strengths and moduli. The values of the strengths and moduli of the PET/acetic‐MWCNT composites were higher than those of the PET/acid‐MWCNT composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Synthesis and characterization of water‐soluble polypyrrole/multi‐walled carbon nanotube composites

Water‐soluble polypyrrole (PPy)/multi‐walled carbon nanotube (MWCNT) composites were prepared by mixing chemically modified MWCNTs carrying carboxylic groups (c‐MWCNTs) and sulfonated PPy (SPPy) aqueous colloids in solution. Fourier transform infrared spectroscopy, Raman spectroscopy, X‐ray photoelectron spectroscopy, X‐ray diffraction, field‐emission scanning electron microscopy and high‐resolution transmission electron microscopy were used to characterize the structure and morphology of the resulting composites. Raman and X‐ray photoelectron spectra demonstrate the presence of electrostatic interactions between the radical species of the SPPy and the carboxylic acid species of the c‐MWCNTs. The addition of c‐MWCNTs into SPPy efficiently enhances its thermal stability and electrical conductivity. Owing to the doping effect and one‐dimensional linear structure of the c‐MWCNTs, the conductivity of SPPy/c‐MWCNT composites at room temperature is increased by two orders of magnitude by the introduction of 5 wt% c‐MWCNTs into the SPPy matrix. Copyright © 2010 Society of Chemical Industry     

The nanocomposites of zinc oxide/L‐amino acid‐based chiral poly(ester‐imide) via an ultrasonic route: Synthesis,characterization, and thermal properties

In this investigation, a chiral poly) ester‐imide) (PEI) via direct polyesterification of N,N′‐(pyromellitoyl)‐bis‐(L ‐tyrosine dimethyl ester) and N‐trimellitylimido‐L ‐methionine was prepared using the tosyl chloride/pyridine/N,N′‐dimethylformamide system as a condensing agent. This approach allows the insertion of two natural amino acids into the polymer backbone and the creation of a bioactive polymer. From the chemical point of view, the ester groups impart to the polymer's main and side chain increased sensibility to hydrolysis that can cause chain breaking. Therefore, this polymer is expected to be biodegradable and could be classified as an eco‐friendly polymer. The polymer also had a useful level of thermal stability associated with excellent solubility. PEI/zinc oxide bionanocomposites were subsequently prepared by an ultrasonic method as a simple and inexpensive route, using ZnO nanoparticles (ZnO‐NPs) modified by 3‐aminopropyltriethoxylsilane (KH550) as a coupling agent. The structure and properties of the obtained BNC polymers were confirmed by Fourier transform infrared spectroscopy, X‐ray diffraction, field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The direct proofs for the formation of the true BNC polymers were provided by TEM. Also, the morphology study of the synthesized polymer‐based BNCs showed well‐dispersed ZnO‐NPs in the polymer matrix by FE‐SEM analysis. TGA studies indicated that an increase of the NP content led to an enhancement of the thermal stability of the new BNC polymers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Silane Modification of Carbon Nanotubes and Preparation of Silane Cross‐Linked LLDPE/MWCNT Nanocomposites

The objective of this study is to investigate the effects of carbon nanotube (CNT) content, surface modification, and silane cross‐linking on mechanical and electrical properties of linear low‐density polyethylene/multiwall CNT nanocomposites. CNTs were functionalized by vinyltriethoxysilane to incorporate the ─O─C2H5 functional groups and were melt‐blended with polyethylene. Silane‐grafted polyethylene was then moisture cross‐linked. Silanization of CNT was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and EDX analysis. Hot‐set test results showed that silane cross‐linking of polyethylene and incorporation of modified CNTs into polyethylene led to an increase in cross‐linking density and the number of entanglements resulting in a decrease in elongation. It was found that the addition of pristine multiwall carbon nanotubes (MWCNTs) and functionalized MWCNTs does not affect silane cross‐linking density. Silane modification resulted in a stronger adhesion of the silane cross‐linked LLDPE to silanized MWCNTs according to scanning electron microscopy micrographs. Additionally, the electrical tests revealed that the silane modification of CNTs results in an improvement in electrical properties of nanocomposites, while silane cross‐linking will not have an effect on electrical properties. Rheological properties of MWCNT/LLDPE nanocomposites have been studied thoroughly and have been discussed in this study. Moreover, according to TGA test results, modification of the MWCNTs led to a better dispersion of them in the LLDPE matrix and consequently resulted in an improvement in thermal properties of the nanocomposites. Crystallinity and melting properties of the nanocomposites have been evaluated in detail using DSC analysis. J. VINYL ADDIT. TECHNOL., 26:113–126, 2020. © 2019 Society of Plastics Engineers     

Preparation of epoxy composites with CTAB‐modified BN and MWCNTs

In this study, multi‐walled carbon nanotubes (MWCNTs) and boron nitride (BN) were functionalized with cetyltrimethylammonium bromide (CTAB) at both pH 5.5 and pH 11. These MWCNT‐CTAB and BN‐CTAB particles used to prepare the composites were dispersed in a bisphenol A (DGEBA)‐type epoxy resin (ER) system at room temperature. The TGA analysis showed that the BN composite can significantly improve the thermal stability of neat ER at temperatures above 400 °C. The curing degrees of the nanocomposites were calculated to be approximately the same values as neat ER using the Beer–Lambert law from FTIR spectra. The best electrical conductivity of the composites obtained was 3.10 × 10⁻³ S/cm for ER/MWCNT‐CTAB (pH 5.5). The surface hardness, Young's modulus, and tensile strength of the composites were examined. The surface hardness values of the ER/MWCNT‐CTAB composites were higher than those of the other composites. The composite morphology was characterized using X‐ray diffraction (XRD) and scanning electron microscopy (SEM). POLYM. COMPOS., 37:3423–3432, 2016. © 2015 Society of Plastics Engineers     

Preparation of polybenzimidazole/functionalized carbon nanotube nanocomposite films for use as protective coatings

Functionalized multi‐walled carbon nanotubes (MWCNTs) via microwave‐induced polymerization modification route, and polybenzimidazole (PBI) nanocomposite films containing 0.1‐5 wt% functionalized MWCNTs were successfully synthesized. The functionalized MWCNTs were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and X‐ray photoelectron spectroscopy (XPS). The results verify that the polymer was successfully grafted to the MWCNTs with a polymer layer that was several nanometers thick. The TGA results showed that the quantity of the attached polymer reached approximately 9.4 wt%. The mechanical properties of the nanocomposite films were measured by tensile test and dynamic mechanical analysis (DMA). The tensile test results indicated that the Young's modulus increased by about 43.9% at 2 wt% CNT loading, and further modulus growth was observed at higher filler loading. The DMA studies indicated that the nanocomposite films had a higher storage modulus than pure PBI film in the temperature range of 30‐300°C, and the storage modulus was maintained above 0.82 GPa. Simulation results confirmed that the PBI nanocomposite films had desirable mechanical properties for use as a protective coating. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.