High thermal conductive m‐xylylenediamine functionalized multiwall carbon nanotubes/epoxy resin composites

In this study, multiwall carbon nanotubes (MWNTs) functionalized by m‐xylylenediamine is used as thermal conductive fillers to improve their dispersibility in epoxy resin and the thermal conductivity of the MWNTs/bisphenol‐A glycidol ether epoxy resin composites. Functionalization with amine groups of MWNTs is achieved after such steps as carboxylation, acylation and amidation. The thermal conductivity, impact strength, flexural strength, and fracture surfaces of MWNTs/epoxy composites are investigated with different MWNTs. The results show that m‐xylylenediamine is successfully grafted onto the surface of the MWNTs and the mass fraction of the organic molecules grafted onto MWNTs is about 20 wt %. The thermal conductivity of MWNTs/epoxy composites is further enhanced to 1.236 W/mK with 2 wt % m‐MWNTs. When the content of m‐MWNTs is 1.5 wt %, the impact strength and flexural strength of the composites are 25.85 KJ/m², 128.1 MPa, respectively. Scanning electron microscope (SEM) results show that the fracture pattern of composites is changed from brittle fracture to ductile fracture. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41255.     

Non‐covalent interactions of pyrene end‐labeled star poly(ɛ‐caprolactone)s with fullerene

Pyrene end‐labeled star poly(?‐caprolactone)s (PCLs) with polyhedral oligomeric silsesquioxane (POSS) core were prepared by combination of copper(I)‐catalyzed azide–alkyne cycloaddition (CuAAC) click chemistry and ring‐opening polymerization techniques. First, ?‐caprolactone (?‐CL) is polymerized by using 1‐pyrene methanol as initiator and stannous octoate as catalyst to obtain α‐pyrene‐ω‐hydroxyl telechelic PCL with different chain lengths. Then, its hydroxyl group is converted to acetylene functionality by esterification reaction with propargyl chloroformate. Finally, the CuAAC click reaction of α‐pyrene‐ω‐acetylene telechelic PCL with POSS‐(N₃)₈ leads to corresponding pyrene end‐labeled star‐shaped PCLs. The successful synthesis of pyrene end‐labeled star polymers is clearly confirmed by ¹H‐nuclear magnetic resonance, Fourier transform infrared, gel permeation chromatograph, differential scanning calorimeter, and thermogravimetric analysis. Furthermore, non‐covalent interactions of obtained star polymers with fullerene are investigated in liquid media. Based on Raman spectroscopy and visual investigations, the star polymer having shorter chain length exhibited better and more stable dispersion with fullerene. The amount of pyrene units present per polymer chains can directly influence the dispersion stability of fullerene. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46520.     

Thermal‐initiated hydroxyethyl methacrylate functionalization of multiwalled carbon nanotubes

Multiwalled‐carbon nanotubes (MWCNTs) were functionalized via thermoinitiated free radical polymerization of 2‐hydroxyethyl methacrylate (HEMA) using benzoyl peroxide. Tip sonication was used during the polymerization reaction to separate agglomerated nanotubes. The functionalization was confirmed by control experiments and attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR). Differential scanning calorimetry indicated that the addition of poly(HEMA)‐MWCNTs to a two‐component polyurethane coating will have little effect on the glass transition temperature of the coating. The poly(HEMA)‐functionalized MWCNTs formed large colloidal structures of highly dispersed nanotubes in both the nonsheared and sheared coatings as determined by atomic force microscopy. This study determined a quick and easy method to functionalize MWCNTs for incorporation into a two‐component polyurethane coating. A simple method for producing ordered structures of the MWCNTs via shear observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Poly(2,6‐di(thiophene‐2‐yl)‐3,5bis(4‐(thiophene‐2‐yl)phenyl)dithieno [3,2‐b;2',3'‐d]thiophene)/carbon nanotube composite for capacitor applications

A novel monomer, 2,6‐di(thiophene‐2‐yl)‐3,5bis(4‐(thiophene‐2‐yl)phenyl)dithieno[3,2‐b;2',3'‐d]thiophene ( Th₄DTT) has been synthesized and used as an electro‐active material. It has been electropolymerized onto glassy carbon (GC) electrode in sodium dodecyl sulfate (SDS) solution (0.1 M) together with multi‐walled carbon nanotubes (MWCNT). A good capacitive characteristics for P(Th₄DTT)/MWCNT composite has been obtained by electrochemical impedance spectroscopy (EIS), which is, to our best knowledge, the first report on capacitor behavior of a dithienothiophene. A synergistic effect has been resolved by Nyquist, Bode‐magnitude—phase and admittance plots. Specific capacitance of the conducting polymer/MWCNT, calculated from cyclic voltammogram (CV) together with area and charge formulas, has been found to be 20.17 F g^?1. Long‐term stability of the capacitor has also been tested by CV, and the results indicated that, after 500 cycles, the specific capacitance is 87.37% of the initial capacitance. An equivalent circuit model of R_s(C₁(R₁(Q(R₂W))))(C₂R₃) has been obtained to fit the experimental and theoretical data. The double layer capacitance (C_dl) value of P(Th₄DTT)/MWCNT (4.43 mF cm^?2) has been found to be 25 times higher than P(Th₄DTT) (C_dl= 0.18 mF cm^?2). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40061.     

High‐performance natural rubber latex composites developed by a green approach using ionic liquid‐modified multiwalled carbon nanotubes

The effect of multiwalled carbon nanotubes (MWCNTs) modified by a hydrophilic ionic liquids (ILs), including 1‐ethyl‐3‐methylimidazolium bromide and 1‐hexyl‐3‐methylimidazolium bromide, was studied. The obtained water‐suspensible carbon nanotubes (CNTs) were still homogeneously distributed in water a month after sonication. The microstructural development of filler networks and the uniform dispersion of MWCNTs in the presence of IL were analyzed by TEM. The apparent physical (cation–π/π–π) interaction between the MWCNTs and the IL was characterized by Raman spectroscopy, DSC, and TGA. Furthermore, high‐performance composites of natural rubber latex (NRL) and CNTs modified with IL were obtained by the liquid latex blending method. The CNTs were homogeneously distributed in the matrix and CNT–ILs improved the fatigue resistance and mechanical properties of the NRL/CNT–IL composites. This study demonstrates a simple and eco‐friendly approach to develop multifunctional advanced materials based on IL‐modified MWCNT elastomer composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46588.     

PMMA composites of single‐walled carbon nanotubes‐graft‐PMMA

To facilitate the dispersion of single‐walled carbon nanotubes (SWCNT) into poly(methyl methacrylate) (PMMA), SWCNT were functionalized with a RAFT chain transfer agent, and PMMA was grafted from the SWCNT by reversible addition–fragmentation transfer (RAFT) polymerization to give SWCNT‐g‐PMMA containing 6 wt % PMMA. SWCNT‐g‐PMMA in the form of small bundles was dispersed into PMMA matrices. The SWCNT‐g‐PMMA filler increased the glass transition temperature (T_g) of the composite when the matrix molecular weight M_n was less than the graft molecular weight, but not when the matrix M_n was equal to or greater than the graft M_n. The threshold of electrical conductivity of the composites as a function of weight percent SWCNT increased from 0.2% when matrix M_n was less than graft M_n to about 1% when matrix M_n was greater than graft M_n. Dynamic mechanical analyses of the composites having graft M_n less than or equal to matrix M_n showed broader rubbery plateaus with increased SWCNT content but no significant differences between samples with different grafted PMMAs. The results indicate that lower M_n matrix wets the SWCNT‐g‐PMMA whereas higher M_n matrix does not wet the SWCNT‐g‐PMMA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39884.     

Amino-functionalized carbon nanotubes for effectively improving the mechanical properties of pre-impregnated epoxy resin/carbon fiber

Pre-impregnated carbon fiber/epoxy resin (CF/epoxy prepreg) gained its popularity for significant stress applications, especially in the aerospace industry, owing to its excellent resistance and low specific mass. However, these CF/epoxy prepregs have a tendency to crack propagation. A solution for the prepregs fragility is the addition of carbon nanotubes (CNTs), especially those functionalized with amino groups, reinforcing the material due to its exceptional mechanical properties. In this work, the influence of the carbon chain length of two different amino-functionalized CNTs from diverse backgrounds (commercial and laboratory growth CNTs) is studied. The nanofillers were added in CF/epoxy prepregs by dry spraying without solvent aid. CNTs' samples were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and thermogravimetric analysis (TGA), while the composites were analyzed by TGA, dynamic-mechanical analysis, and field emission scanning electron microscopy. The various surface treatment occurred at different levels according to the CNTs background, and all samples exhibited a distinct behavior. These differences were also observed in the composites' thermomechanical performance: CNTs functionalized with larger carbon chain amine presented the best results, with an increase of almost 100% in the storage moduli (E'), confirming the efficiency of amino-functionalized CNTs in the reinforcement of CF/epoxy prepregs.     

Functionalization of carbon nanotubes with (3‐glycidyloxypropyl)‐trimethoxysilane: Effect of wrapping on epoxy matrix nanocomposites

In this work, multiwalled carbon nanotubes (MWCNT), after previous oxidation, are functionalized with excess (3‐glycidyloxypropyl)trimethoxysilane (GLYMO) and used as reinforcement in epoxy matrix nanocomposites. Infrared, Raman, and energy‐dispersive X‐ray spectroscopies confirm the silanization of the MWCNT, while transmission electron microscopy images show that oxidized nanotubes presented less entanglement than pristine and silanized MWCNT. Thickening of the nanotubes is also observed after silanization, suggesting that the MWCNT are wrapped by siloxane chains. Field‐emission scanning electron microscopy reveals that oxidized nanotubes are better dispersed in the matrix, providing nanocomposites with better mechanical properties than those reinforced with pristine and silanized MWCNT. On the other hand, the glass transition temperature of the nanocomposite with 0.05 wt % MWCNT‐GLYMO increased by 14 °C compared to the neat epoxy resin, suggesting a strong matrix–nanotube adhesion. The functionalization of nanotubes using an excess amount of silane can thus favor the formation of an organosiloxane coating on the MWCNT, preventing its dispersion and contributing to poor mechanical properties of epoxy nanocomposites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44245.     

Influence of preparation methods on the electrical and nanomechanical properties of poly(methyl methacrylate)/multiwalled carbon nanotubes composites

Poly(methyl methacrylate)/multiwalled carbon nanotubes (PMMA/MWCNT) composites were prepared by two different methods: melt mixing and solution casting. For solution casting, two different solvents, toluene and chloroform, were used to prepare PMMA solutions with different concentrations of MWCNT. The dispersion of the CNT in the composite samples was verified by scanning electron microscopy. For the nanocomposites prepared by both methods, the electrical conductivity increased with increasing filler content, showing typical percolation behavior. In addition, an increase of 11 orders of magnitude in the electrical conductivity relative to the matrix conductivity was determined by broadband dielectric spectroscopy and four probe conductivity measurements. A maximum value of σ_DC ～ 1.6 S/cm was found for the highest filler loaded sample (3.67 vol %), which was prepared by solution casting from toluene. Nanoindentation analysis was used to characterize the surface mechanical properties of the composite samples prepared by the different methods. Indentation tests were performed at various penetration depths, and it was revealed that the melt mixing process resulted in stiffer neat PMMA samples compared to the solution casted PMMA samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41721.     

Electrical conductivity and tensile properties of block‐copolymer‐wrapped single‐walled carbon nanotube/poly(methyl methacrylate) composites

Poly(methyl methacrylate) (PMMA) composites containing raw or purified single‐walled carbon nanotubes (SWCNTs) are prepared by in situ polymerization and solution processing. The SWCNTs are purified by centrifugation in a Pluronic surfactant, which consists of polyethyleneoxide and polypropyleneoxide blocks. Both the effects of SWCNT purity and non‐covalent functionalization with Pluronic are evaluated. Electrical conductivity of PMMA increases by 7 orders of magnitude upon the integration of raw or purified SWCNTs. The best electrical properties are measured for composites made of purified SWCNTs and prepared by in situ polymerization. Strains at fracture of the SWCNT/PMMA composites are nearly identical to those of the neat matrix. A certain decrease in the work to fracture is measured, particularly for composites containing purified SWCNTs (?31.6%). Fractography and Raman maps indicate that SWCNT dispersion in the PMMA matrix improves upon the direct addition of Pluronic, while dispersion becomes more difficult in the case of purified SWCNTs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41547.     

Crystallization and mechanical behavior of covalent functionalized carbon nanotube/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) nanocomposites

To improve the dispersity of multi‐walled carbon nanotubes (MWCNTs) in poly(3‐hydroxybutyrate‐co?3‐hydroxyvalerate) (PHBV) matrix, MWCNTs functionalized with carboxyl groups, hydroxyl groups, and atactic poly (3‐hydroxybutyrate) (ataPHB) through acid oxidation, esterification reaction, and “grafting from” method, respectively, were used to fabricate nanofiller/PHBV nanocomposites. The crystallization behavior, dispersion of MWCNTs before and after functionalization in PHBV matrices, and mechanical properties of a series of nanocomposites were investigated. The differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized optical microscope results suggested that the four types of MWCNTs acted as effective heterogeneous nucleation agents, inducing an increase in the crystallization rate, crystallinity, and crystallite size. Scanning electron microscope observations demonstrated that functionalized MWCNTs showed improved dispersion comparing with MWCNTs, suggesting an enhanced interfacial interaction between PHBV and functionalized MWCNTs. Consequently, the mechanical properties of the functionalized MWCNTs/PHBV nanocomposites have been improved as evident from dynamic mechanical and static tensile tests. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42136.     

The effect of surface treatment on graphite nanoplatelets used in fiber reinforced composites

Atmospheric plasma treatment (APT) was used to surface‐activate graphite nanoplatelets (GnP) as well as highly graphitic P100 fibers used to manufacture composites. X‐ray photoelectron spectroscopy showed an increase in the O/C ratio of the treated surfaces when using either CO or O₂ as the active gas, whereas CO exhibited less damage to the treated reinforcement carbon material. APT of P100 fibers resulted in a 75% increase in composite tensile strength when compared to composites using untreated fibers. Surface treatment of GnPs also resulted in GnP/epoxy composites with significantly higher glass transition temperatures (Tg's) and 50% higher flexural strengths than those with no surface treatment because of stronger particle‐to‐resin coupling, which was also evidenced by the fracture surfaces. The effect of GnP loading concentration and plasma treatment duration was also evaluated on the tensile strength of fiber‐reinforced composites. The addition of untreated GnP filler resulted in a decrease in strength up to the 1% loading. However, higher loading conditions resulted in a 20% improvement because of GnP orientation effects. Fracture surfaces suggest that the fibers provided a mechanism for the GnPs to orient themselves parallel to the fiber axis, developing an oriented matrix microstructure that contributes to added crack deflection. Incorporating surface‐treated GnPs in these composites resulted in tensile strengths that were as high as 50% stronger than the untreated systems for all loading conditions. Increased GnP‐to‐matrix bonding as well as enhanced orientation of the GnPs resulted in multifunctional composites with improved mechanical performance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39994.     

Preparation and characterization of P(AN‐co‐VA‐co‐DEMA) fibers coated with multiwalled carbon nanotubes by electrostatic interactions

P(AN‐co‐VA‐co‐DEMA) terpolymers were synthesized by aqueous precipitation copolymerization of acrylonitrile (AN), vinyl acetate (VA), and 2‐dimethylamino ethyl methacrylate (DEMA) with an Na₂S₂O₅–NaClO₃ redox initiating system and fibers from these terpolymers were thus prepared by a wet spinning method. Functionalized multiwalled carbon nanotube (F‐MWNT) networks were created on the surface of P(AN‐co‐VA‐co‐DEMA) fibers by a simple dipping method. The morphology and interfacial interactions of the obtained F‐MWNTs‐coated fibers were characterized by scanning electron microscope, Raman spectroscopy, and Fourier transform infrared spectroscopy. The results showed that F‐MWNTs were assembled on the fibers and the density of F‐MWNTs can be controlled by adjusting the F‐MWNTs content in the dipping solution. The assembly process was driven by electrostatic interactions between the negative charges on the nanotube sidewalls and the positive charges of the fibers. The F‐MWNTs‐coated fibers had a good conductivity. The volume resistivity of the fibers coated with 1.18 wt % F‐MWNTs reached 0.27 Ω·cm, while the original mechanical properties were preserved. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42545.     

Improving dispersion of multiwalled carbon nanotubes in polyamide 6 composites through amino‐functionalization

The focus of this study is to investigate the state of dispersion of different treated multiwalled carbon nanotubes (MWNTs) in polyamide 6 (PA6). The MWNTs used in composites were grafted by 1,6‐hexamethylenediamine (HMD) via acid‐thionyl chloride to improve their compatibility with PA6 matrix. A microstructure transformation of MWNTs is found during the treatment process. Acidification makes the MWNTs compact and grafting HMD promotes the compact structure loose again. The MWNTs after different treatment were used to fabricate MWNTs/PA6 composites through melt blending. The dispersion of different MWNTs in PA6 was observed by a combination of scanning electron microscopy, optical microscopy, and transmission electron microscopy. The results show that the amino‐functionalized MWNTs are dispersed more homogeneously in PA6 than the purified MWNTs, and the poorest dispersion is achieved for acid treated MWNTs. It is indicated that the loose structure and functionalized surface of MWNTs benefit the dispersion of MWNTs in PA6. In addition, the amino‐functionalization of MWNTs improves the compatibility between the MWNTs and PA6, resulting in stronger interfacial adhesion. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

High-performance sodium polyacrylate nanocomposites developed by using ionic liquid covalently modified multiwalled carbon nanotubes

Ionic liquids grafted with multiwalled-nanotubes (CNT Br/NTf₂), involving hydrophilic bromide salt and hydrophobic bis(trifluoromethanesulphonyl)imide salt, were prepared by amidation, followed by an easy solution-casting method of blending CNT Br/NTf₂ with sodium polyacrylate (PAA) as well as crosslinking agent (XR-100) to form PAA hybrid nanocomposites. The uniform dispersion of CNT Br/NTf₂ were analyzed by TEM. The defects and physical properties of fillers were characterized by Raman spectroscopy, Contact angle test, and TGA. Furthermore, microstructures of hybrid nanocomposites were characterized by SEM, from which it can be found that fillers were homogeneously distributed in the PAA matrix. CNT Br/NTf₂ significantly improved the mechanical properties and tensile fatigue resistance, as well as offered tunable swelling behavior of PAA nanocomposites without wasting too much of thermal stability. This study offers a simple approach to develop multifunctional materials based on ionic liquids covalently modified MWCNTs PAA nanocomposites.     

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.     

Nanostructured thermosetting epoxy systems modified with poly(isoprene‐b‐methyl metacrylate) diblock copolymer and polyisoprene‐grafted carbon nanotubes

Nanostructured thermosetting composites based on an epoxy matrix modified with poly(isoprene‐b‐methyl methacrylate) (PI‐b‐PMMA) block copolymer were prepared through PI block segregation. Morphological structures were examined by means of atomic microscopy force microscopy. As epoxy/pristine multi‐walled carbon nanotubes (MWCNT) systems were found to present big agglomerations, with a very poor dispersion of the nanofiller, epoxy/PI‐b‐PMMA/MWCNT systems were prepared by using polyisoprene‐grafted carbon nanotubes (PI‐g‐CNT) to enhance compatibility with the matrix and improve dispersion. It was found that the functionalization of MWCNT with grafted polyisoprene was not enough to totally disperse them into the epoxy matrix but an improvement of the dispersion of carbon nanotubes was achieved by nanostructuring epoxy matrix with PI‐b‐PMMA when compared with epoxy/MWCNT composites without nanostructuring. Nevertheless, some agglomerates were still present and the complete dispersion or confinement of nanotubes into desired domains was not achieved. Thermomechanical properties slightly increase with PI‐g‐CNT content for nanostructured samples, whereas for nonnanostructured epoxy/PI‐g‐CNT composites they appeared almost constant and even decreased for the highest nanofiller amount due to the presence of agglomerates. Compression properties slightly decreased with block copolymer content, while remained almost constant with nanofiller amount. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Comparison of covalent and noncovalent interactions of carbon nanotubes on the crystallization behavior and thermal properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)

In this study, multiwalled carbon nanotubes (MWCNTs) were dispersed into a poly(3‐hydroxybutyrate‐co?3‐hydroxyvalerate) (PHBV) matrix, in which PHBV was either covalently attached to the nanotubes through an esterification reaction between the carboxylic groups of functionalized MWCNTs and the hydroxyl groups of PHBV with toluene diisocyanate as a coupling agent or physically mixed to result in only noncovalent interactions. The structure, crystallization behavior, and thermal properties of the resulting nanocomposites were studied. We found that the crystallization of PHBV grafted onto the MWCNTs (PHBV‐g‐MWCNTs) was markedly hindered and exhibited an exothermic peak caused by cold crystallization, whereas the nonisothermal crystallization of PHBV was enhanced because a heterogeneous nucleation effect appeared in the PHBV/MWCNTs. Moreover, the maximum decomposition temperature of the PHBV‐g‐MWCNTs was improved by about 14.4°C compared with that of the PHBV/MWCNTs and by about 23.7°C compared with that of the original PHBV. Furthermore, the PHBV‐g‐MWCNTs exhibited the wider melt‐processing window than the PHBV/MWCNTs and original PHBV. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4299–4307, 2013     

Effectiveness of the preparation of maleic anhydride grafted poly (lactic acid) by reactive processing for poly (lactic acid)/carbon nanotubes nanocomposites

An effective strategy to increase the properties of poly (lactic acid) (PLA) is the addition of carbon nanotubes (CNT). In this work, aiming to improve the surface adhesion of PLA and CNT a new compatibilizer agent was prepared by reactive processing, PLA grafted maleic anhydride (PLA-g-MA) using benzoyl peroxide and maleic anhydride. The effectiveness of the PLA-g-MA as a compatibilizer agent was verified for PLA/PLA-g-MA/CNT nanocomposites. PLA and PLA-g-MA samples were characterized by Fourier transform infrared spectroscopy (FT-IR) to confirm the grafting reaction of maleic anhydride on PLA chains and by rheological analysis to prove the changes in the matrix PLA after the graphitization reaction. Thermal (differential scanning calorimetry and thermogravimetric analysis), mechanical tests (Izod impact strength and tensile test), and morphological characterization were used to verify the effect of the compatibilizer agent. The preparation of PLA-g-MA by reactive extrusion processing proved satisfactory and the nanocomposites presented good thermal and mechanical properties. The addition of the PLA-g-MA also contributed to the greater distribution of CNT and can be used as an alternative for the production of PLA/CNT nanocomposites.     

Mechanical properties of carbon fiber reinforced bisphenol A dicyanate ester composites modified with multiwalled carbon nanotubes

A novel electrophoretic deposition (EPD) method was employed for grafting multiwalled carbon nanotubes (MWCNTs) on carbon fibers, which, after impregnation with bisphenol A dicyanate ester (BADCy), synergistically reinforced BADCy matrix composites (CNT‐C/BADCy). The effect of MWCNT presence on the mechanical properties of the composites was investigated. Composite tensile strength increased by 45.2% for an EPD duration of 2 min, while flexural strength exhibited a decreasing trend with EPD duration. Optical microscopy revealed that the existence of MWCNTs enhanced the fiber‐matrix interface while a large number of CNTs were observed to have pulled‐out from the matrix, a finding which explained the observed tensile strength increase in terms of energy dissipation by the specific toughening mechanism. The flexural strength decrease of the composites with CNTs as compared to specimens without nanotubes was found linked to the increased stress concentration in the BADCy matrix due to tube presence which weakens the adhesion between carbon fabrics. In a word, carbon nanotubes will enhance the micro interface and weaken the macro interface of the composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45100.