Preparation and properties of plasticized starch/multiwalled carbon nanotubes composites

In this work we have studied the utilization of multiwalled carbon nanotubes (MWCNTs) as filler‐reinforcement to improve the performance of plasticized starch (PS). The PS/MWCNTs nanocomposites were successfully prepared by a simple method of solution casting and evaporation. The morphology, thermal behavior, and mechanical properties of the films were investigated by means of scanning electron microscopy, wide‐angle X‐ray diffraction, differential scanning calorimetry, and tensile testing. The results indicated that the MWCNTs dispersed homogeneously in the PS matrix and formed strong hydrogen bonding with PS molecules. Compared with the pure PS, the tensile strength and Young's modulus of the nanocomposites were enhanced significantly from 2.85 to 4.73 MPa and from 20.74 to 39.18 MPa with an increase in MWCNTs content from 0 to 3.0 wt %, respectively. The value of elongation at break of the nanocomposites was higher than that of PS and reached a maximum value as the MWCNTs content was at 1.0 wt %. Besides the improvement of mechanical properties, the incorporation of MWCNTs into the PS matrix also led to a decrease of water sensitivity of the PS‐based materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

A general and efficient route to covalently surface modification of MWCNTs by dopamine and their synergistic reinforcing effects in chitosan films

Multiwalled carbon nanotubes (MWCNTs) were considered as ideal filler in a polymer matrix due to their outstanding mechanical, electrical and thermal properties. This article describes a simple route to preparation of nanocomposite (NC) of chitosan and modified MWCNT by solution casting method. The process involves modification of MWCNT with dopamine and effects of modified MWCNT on dispersion, mechanical, thermal and morphological properties. Atomic force microscopy, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy, transmission electron microscopy, have been used to characterize the NCs. Scanning electron micrographs showed that in all of the NC films, except chitosan/MWCNT-Dop NC 7 wt%, MWCNT were dispersed homogeneously throughout the chitosan matrix. The XRD studies showed that the crystallinity of composite films decreases through hydrogen bonding between chitosan and MWCNT-Dop. The determination of mechanical and thermal properties demonstrated that the NC films exhibited significant enhancement in strength, modulus, and thermal stability compared with the pure chitosan.     

Thermal and mechanical stabilities of composite films from thiadiazol bearing poly(amide-thioester-imide) and multiwall carbon nanotubes by solution compounding

An amino acid containing poly(amide-thioester-imide) (PATEI) possessing a conjugated thiadiazol ring was shown to be effective for dispersing multiwall carbon nanotubes (MWCNTs) in N,N′-dimethylacetamide. Through casting of these dispersions, MWCNT/PATEI composite films were successfully fabricated on substrates and showed no signs of macroscopic aggregation. To increase the compatibility between PATEI matrix and MWCNTs, carboxyl-functionalized MWCNTs (f-MWCNTs) were used in this study. The f-MWCNTs were dispersed homogeneously in the PATEI matrix while the structure of the polymer and the MWCNTs structure were stable in the preparation process as revealed by transmission electron microscopy. Tensile tests and thermal analysis were carried out on free-standing composite films for different MWCNT loading levels. Results showed that overall mechanical and thermal properties of the composites were greatly improved as compared with the neat PATEI film. Fourier transform infrared spectroscopy, powder X-ray diffraction, and field emission electron microscopy were also used to evaluate the MWCNT/PATEI composite system.     

Effects of glucose‐functionalized multiwalled carbon nanotubes on the structural,mechanical, and thermal properties of chitosan nanocomposite films

A series of multiwalled carbon nanotubes (MWCNTs) grafted by chitosan nanocomposite (NC) films were prepared by a direct blending process and solution casting method. In this study, we modified multiwalled carbon nanotubes with glucose (MWCNT–Gl) for this purpose, and the effects of MWCNT–Gl on the structural, mechanical, and thermal properties of chitosan films with different contents of MWCNT–Gl were investigated. The structure, thermal stability, and mechanical properties of the composite were examined by X‐ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and mechanical testing. The results indicate that the MWCNTs treated by glucose were dispersed well in the chitosan matrix, and the tensile properties of the NC films were improved greatly compared with neat chitosan. Also, with increasing MWCNT–Gl content, the crystalline nature of chitosan decreased. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42022.     

l-Phenylalanine amino acid functionalized multi walled carbon nanotube (MWCNT) as a reinforced filler for improving mechanical and morphological properties of poly(vinyl alcohol)/MWCNT composite

Carbon nanotube dispersion in polymer matrix is one of the most crucially important aspects in carbon nanotube/polymer composites. This paper is aimed to discuss the considerable improvement in dispersion of multi walled carbon nanotubes (MWNTs) in poly(vinyl alcohol) (PVA) matrix that was attained through bio-functionalization of MWCNTs. Initially, for getting better dispersion in water, pure MWCNTs have been functionalized by l-phenylalanine amino acid. The functionalized MWCNTs (f-MWCNTs) show much enhanced solubility in water. So, effects of modified MWCNT on dispersion in PVA matrix and certain properties of the resulting composites, like; mechanical, thermal and morphological properties were studied. The prepared composites were examined by Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. Also, the mechanical and thermal properties of composite films have been investigated and revealed that incorporation of just a few percent of f-MWCNTs can improve the PVA mechanical and thermal properties significantly.     

Polystyrene composites containing crosslinked polystyrene‐multiwalled carbon nanotube balls

Crosslinked polystyrene‐multiwalled carbon nanotube (PS‐MWCNT) balls, which act as conductive microfillers, were prepared by the in situ suspension polymerization of styrene with MWCNTs and divinyl benzene (DVB) as a crosslinking agent. The diameters of the synthesized crosslinked PS‐MWCNT balls ranged from 10 to 100 μm and their electrical conductivity was about 7.7 × 10^?3 S/cm. The morphology of the crosslinked PS‐MWCNT balls was observed by scanning electron microscopy and transmission electron microscopy. The change in the chemical structure of the MWCNTs was confirmed by Raman spectroscopy and Fourier transform infrared spectroscopy. The mechanical and electrical properties of the PS/crosslinked PS‐MWCNT ball composites were investigated. It was found that the tensile strength, ultimate strain, Young's modulus, and impact strength of the PS matrix were enhanced by the incorporation of the crosslinked PS‐MWCNT balls. In addition, the mechanical properties of the PS/crosslinked PS‐MWCNT ball composites were better than those of the PS/pristine MWCNT composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The production of functionalized multiwall carbon nanotube/amino acid-based poly(amide–imide) composites containing a pendant dopamine moiety

The high compatibility of amino-acid based poly(amide–imide) (PAI) as a polymer matrix for acid-modified multi-walled carbon nanotubes (MWCNTs) is discussed. PAI was synthesized from the direct polycondensation reaction of N,N′-(pyromellitoyl)-bis-l-isoleucine with a dopamine-based diamine, 3,5-diamino-N-(3,4-dihydroxy-phenethyl)benzamide, in a medium consisting of a molten salt, tetrabutylammonium bromide, and triphenyl phosphite as the activator under microwave radiation. To obtain a homogeneous dispersion of MWCNTs in the PAI matrix, acid-functionalized MWCNTs were used. Composites containing 5, 10, and 15 wt.% MWCNT–COOH exhibited a relatively good dispersion on the macroscopic scale. MWCNT/PAI composite films have been prepared by casting a solution of precursor polymer containing MWCNTs into a thin film and its tensile properties examined. Incorporation of MWCNTs improved the mechanical properties significantly. Composites were also characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopy, and thermal gravimetric analysis. The thermal stability of the composites containing the CNTs was improved due to the increased interfacial interaction between the PAI matrix and the modified CNTs and their good dispersion.     

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.     

New polyurea MWCNTs nanocomposite films with enhanced mechanical properties

Polyurea nanocomposites represent a promising option in the development of advanced materials for applications that require high mechanical resistance. This article describes an optimized synthetic route for obtaining polyurea nanocomposites with enhanced mechanical properties by employing epoxy‐functionalized multiwalled carbon nanotubes (MWCNTs) as reinforcing agent. The experimental measurements revealed that these functionalized nanofillers have a positive effect on the properties of the composite only until they reach a certain concentration; therefore, the optimal composition was reported (the samples containing 0.2 weight % functionalized MWCNTs). The functionalization of the MWCNTs was confirmed through RAMAN, X‐ray photoelectron spectroscopy, scanning electron microscopy and thermogravimetric analysis, while the polyurea nanocomposites obtained have been characterized by thermal (differential scanning calorimetry and TGA) and mechanical (dynamic mechanical analysis and tensile tests) analyses. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45061.     

Oxidized pea starch/chitosan composite films: Structural characterization and properties

In this article, a series of oxidized pea starch/chitosan (OPS/CS) blend films were prepared by a casting and solvent evaporation method. The structure, thermal behavior, and mechanical properties of the films were investigated by means of Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and tensile testing. The results suggested that, in addition to hydrogen bonding, the interactions between OPS and CS molecules were enhanced by the formation of electrostatic interaction between the negatively charged carboxyl groups on OPS and the positively charged amino groups on CS. Compared with the pea starch/chitosan (PS/CS) blend films, OPS/CS blend films exhibited significantly higher tensile strength with significantly lower elongation at break. Moreover, incorporation of CS into the OPS matrix also led to a decrease in moisture uptake by the composite film. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of castor oil‐based polyurethane/α‐zirconium phosphate composite films

Novel castor oil‐based polyurethane/α‐zirconium phosphate (PU/α‐ZrP) composite films with different α‐ZrP loading (0–1.6 wt %) and different NCO/OH molar ratios were synthesized by a solution casting method. The characteristic properties of the PU/α‐ZrP composite films were examined by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile testing. The results from Fourier transform infrared spectroscopy indicated that strong intermolecular hydrogen bonding formed between α‐ZrP and PU, XRD and SEM results revealed that the α‐ZrP particles were uniformly distributed in the PU matrix at low loading, and obvious aggregation existed at high loading. Because of hydrogen bonding interactions, the maximum values of tensile strength were obtained with 0.6 wt % α‐ZrP loading and 1.5 of NCO/OH molar ratio in the matrix. Evidence proved that the induced α‐ZrP used as a new filler material can affect considerably the mechanical and thermal properties of the composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Tailoring in thermomechanical properties of ethylene propylene diene monomer elastomer with silane functionalized multiwalled carbon nanotubes

The incorporation of silane treated multiwalled carbon nanotubes (S‐MWCNTs) is used as an effective path for tailoring thermomechanical properties of ethylene propylene diene monomer (EPDM). In this study, S‐MWCNTs were introduced into EPDM using internal dispersion kneader and two roller mixing mill. By altering the mass ratio of S‐MWCNTs from 0 to 1, thermal conductivity, thermal stability and phase transition temperatures and their respective enthalpies are discussed of the fabricated nanocomposites. It is observed that silane modification improves their dispersion and increases the interfacial bonding between MWCNTs and polymer matrix. Scanning electron microscopy along energy dispersive spectroscopy analysis is performed to confirm the silane functionalized MWCNTs are selectively distributed in the host polymer. More importantly, an important increase in mechanical properties like ultimate tensile strength and hardness is achieved through introducing silane functionalized MWCNTs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43221.     

Synthesis of mechanically robust antimicrobial nanocomposites by click coupling of hyperbranched polyurethane and carbon nanotubes

This study demonstrates that mechanically robust antimicrobial nanocomposites of multiwalled carbon nanotubes (MWCNTs) and hyperbranched polyurethane (HBPU) can be prepared via a click chemistry reaction. Various compositions of HBPU-functionalized MWCNTs were synthesized from reactions of azide moiety-containing HBPU with alkyne-functionalized MWCNTs. The HBPU-functionalized MWCNTs were characterized morphologically using transmission electron microscopy and field emission scanning electron microscopy and chemically using Fourier transform infrared spectrometry, Raman spectroscopy, and X-ray photoelectron spectroscopy. The functionalized MWCNTs exhibited excellent dispersion in the HBPU matrix, and as a result, superior mechanical and strong antibacterial properties were obtained. The antimicrobial properties were examined by use of gram-negative bacteria Escherichia coli (E. coli). Consequently the click coupled bonding of MWCNTs with HBPU was very efficient for regulating the composite properties and achieving high performance materials.     

Preparation and properties of MWCNTs/poly(acrylonitrile‐ styrene‐butadiene)/epoxy hybrid composites

Poly(acrylonitrile‐styrene‐butadiene) (ABS) was used to modify diglycidyl ether of bisphenol‐A (DGEBA) type epoxy resin, and the modified epoxy resin was used as the matrix for making multiwaled carbon tubes (MWCNTs) reinforced composites and were cured with diamino diphenyl sulfone (DDS) for better mechanical and thermal properties. The samples were characterized by using infrared spectroscopy, pressure volume temperature analyzer (PVT), thermogravimetric analyzer (TGA), dynamic mechanical analyzer (DMA), thermo mechanical analyzer (TMA), universal testing machine (UTM), and scanning electron microscopy (SEM). Infrared spectroscopy was employed to follow the curing progress in epoxy blend and hybrid composites by determining the decrease of the band intensity due to the epoxide groups. Thermal and dimensional stability was not much affected by the addition of MWCNTs. The hybrid composite induces a significant increase in both impact strength (45%) and fracture toughness (56%) of the epoxy matrix. Field emission scanning electron micrographs (FESEM) of fractured surfaces were examined to understand the toughening mechanism. FESEM micrographs reveal a synergetic effect of both ABS and MWCNTs on the toughness of brittle epoxy matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Highly stable polyimide composite films based on 1,2,4-triazole ring reinforced with multi-walled carbon nanotubes: Study on thermal,mechanical, and morphological properties

A novel diamine bearing aromatic pendant triazole ring, namely, 3,5-diamino-N-(1H-[1,2,4]triazol-3-yl)-benzamide, was successfully synthesized. The prepared diamine and a commercial dianhydride were reacted in situ in the presence of carboxylated multi-walled carbon nanotubes (MWCNTs) with stirring to give a homogeneous MWCNT/poly(amic acid) mixture which was then heated under a heating program to give a series of MWCNT/polyimide (PI) composites with different proportions of MWCNT (5, 10, and 15 wt%). The composite films were tested for different properties including spectral, morphological, thermal, and mechanical properties. Scanning and transmission electron microscopy revealed the modified MWCNTs were well dispersed in the PI matrix while the structure of the polymer and the MWCNTs structure were stable in the preparation process. The thermal stability of the films containing MWCNTs was improved as the MWCNT content increased from 5 to 15 wt% due to the improved interfacial interaction between the PI matrix and surface-modified MWCNTs. Tensile tests on the composites showed an increase in the elastic modulus and the yield strength, and decrease in the failure strain.     

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.     

Mechanical and UV absorption behavior of zinc oxide nanoparticles: reinforced poly(vinyl alcohol-<Emphasis Type="Italic">g</Emphasis>-acrylonitrile) nanocomposite films

In the present work PVA-g-PAN/ZnO nanocomposite films were prepared by free radical graft copolymerization of acrylonitrile on to PVA and subsequent in situ precipitation of ZnO nanoparticles into the polymer matrix. The films were characterized by FTIR, Raman spectroscopy, differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The size of the crystallites and extents of crystallinity were ascertained by X-ray diffraction (XRD) analysis. The SEM with energy dispersive X-ray analysis (EDX) showed that the ZnO nanoparticles were uniformly dispersed within the host grafted copolymer matrix. The transmission electron microscopy (TEM) results clearly indicated that the size of nanoparticles varied in the range 10–30 nm. The UV-absorption properties showed that the films were capable of absorbing more than 95% of UV radiations. Photoluminescence (PL) measurements revealed the presence of defects in the synthesized nanocomposite films. The mechanical properties of the PVA-g-PAN/ZnO nanocomposites such as microhardness and tensile strength were also studied.     

Processability,property, and morphology of biodegradable blends of poly(propylene carbonate) and poly(ethylene‐co‐vinyl alcohol)

Biodegradable blends of poly(propylene carbonate) (PPC) and poly(ethylene‐co‐vinyl alcohol) (EVOH) were melt compounded in a batch mixer followed by compression molding. The processability, mechanical properties, thermal behavior, and morphologies of the blends were investigated with torque rheometer, Fourier transform infrared spectroscopy, tensile tests, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Torque rheometry indicated good interfacial miscibility between PPC and EVOH phases, and then fourier transform infrared spectroscopy spectra demonstrated that a certain extent of hydrogen‐bonding interactions between PPC and EVOH matrix in the blends. A study of the mechanical properties and thermal behavior showed that the EVOH incorporation can significantly enhance the tensile strength, thermal stability, and crystallinity of the blends. Moreover, dynamic mechanical analysis and differential scanning calorimetry both revealed that PPC and EVOH were compatible to some extent. Further, scanning electron microscopic examination also revealed the good interfacial adhesion between EVOH and PPC phases. POLYM. ENG. SCI., 47:174–180, 2007. © 2007 Society of Plastics Engineers     

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     

Properties of PMMA/Carbon nanotubes nanocomposites prepared by “grafting through” method

A number of batch polymerizations were performed to study the effect of multi‐walled carbon nanotubes (MWCNTs) on the properties of PMMA/MWCNTs nanocomposites. To improve the dispersion of nanotubes in PMMA matrix, MWCNTs were functionalized with methacrylate groups via a four‐step modification process and the modified nanoparticles were used to synthesize the nanocomposites. The prepared samples were characterized by Raman spectroscopy, thermogravimetric analysis, dynamic mechanical thermal analysis, differential scanning calorimetry, gel permeation chromatography, UV–visible, and TEM techniques. According to the results, modified nanotubes improved thermal and mechanical properties better than the pristine MWCNTs. The main improvement in the mechanical and thermophysical properties was achieved for the nanocomposite containing 0.5 wt% of MWCNTs. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers