In situ polymerization,thermal, damping,and mechanical properties of multiwalled carbon nanotubes/polyisobutylene‐based polyurethane nanocomposites

Despite the development of strong, durable, and cost efficient polyisobutylene‐based polyurethane (PIB‐based PU) materials has yet to be achieved. The well dispersion and maximum interfacial interaction between the nanofiller and the PIB‐based PU at low loading have been scarcely studied. Here, the preparation of PIB‐based PU nanocomposites with Multiwalled carbon nanotubes (MWCNTs) using a simple in situ polymerization method is reported. The thermogravimetric analysis tests show that MWCNTs significantly improved the thermal stability of MWCNTs/PIB‐based PU nanocomposites. Compare to the pure PIB‐based PU the onset temperature of degradation for the nanocomposite was about 20°C higher at 0.7 wt% MWCNTs loading. Efficient load transfer is found between the nanofiller MWCNTs and PIB‐based PU and the mechanical properties of the MWCNTs/PIB‐based PU nanocomposite with well dispersion are improved. A 63% improvement of Young's modulus and slightly increased of tensile strength are achieved by addition of only 0.7 wt% of MWCNTs. The experimentally determined Young's modulus is in well agreement with the theoretical simulation. It is worth noting that the PIB‐based PU and MWCNTs/PIB‐based PU nanocomposites exhibit excellent damping properties (tan δ > 0.3) from −45°C to 8°C. POLYM. COMPOS., 36:198–203, 2015. © 2014 Society of Plastics Engineers     

Thermal conductivity and dynamic mechanical property of glycidyl methacrylate‐grafted multiwalled carbon nanotube/epoxy composites

The well dispersed multiwalled carbon nanotube (MWCNT)/epoxy composites were prepared by functionalization of the MWCNT surfaces with glycidyl methacrylate (GMA). The morphology and thermal properties of the epoxy nanocomposites were investigated and compared with the surface characteristics of MWCNTs. GMA‐grafted MWCNTs improved the dispersion and interfacial adhesion in epoxy resin, and enhanced the network structure. The storage modulus of 3 phr GMA‐MWCNTs/epoxy composites at 50°C increased from 0.32 GPa to 2.87 GPa (enhanced by 799%) and the increased tanδ from 50.5°C to 61.7°C (increased by 11.2°C) comparing with neat epoxy resin, respectively. Furthermore, the thermal conductivity of 3 phr GMA‐MWCNTs/epoxy composite is increased by 183%, from 0.2042 W/mK (neat epoxy) to 0.5781 W/mK. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Novel nanocomposite of poly(acrylonitrile‐co‐glycidyl methacrylate) crosslinked with Jeffamine‐functionalized multiwalled carbon nanotubes as gel polymer electrolytes

Multiwalled carbon nanotubes (MWCNTs) were functionalized with α,ω‐diamino poly(propylene oxide) (Jeffamine) of different molecular weights and crosslinked with poly(acrylonitrile‐co‐glycidyl methacrylate) [P(AN‐GMA)] to prepare a novel nanocomposite for applications in gel polymer electrolytes (GPEs). The synthesized copolymer was characterized by ¹H‐NMR, Fourier transform infrared, and thermal analysis. Scanning electron microscope observation revealed that the Jeffamine‐functionalized MWCNTs distributed uniformly in the nanocomposite membrane. The mechanical behaviors of the nanocomposite membranes were investigated. It was found that the crosslinked nanocomposite membranes of P(AN‐GMA) and Jeffamine‐functionalized MWCNTs exhibited much higher mechanical strength than the counterpart nanocomposite obtained by physical blending. Moreover, the weight content and molecular weights of Jeffamine had an effect on the mechanical properties of the nanocomposites. Differential scanning calorimeter measurements showed that the crosslinked nanocomposite membranes were amorphous. GPEs based on the nanocomposite were prepared and characterized by complex impedance measurements. The GPE based on the nanocomposite of P(AN‐GMA) crosslinked with 6 wt % of MWCNTs functionalized by Jeffamine D400 showed an ionic conductivity of about 3.39 × 10^?4 S cm^?1 at 25°C, which is much higher than the counterpart nanocomposite of physically blended P(AN‐GMA) and MWCNTs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mechanical and thermal properties of biphenyldiol formaldehyde resin/gallic acid epoxy composites enhanced by graphene oxide

In this study, the gallic acid‐based epoxy resin (GA‐ER) and alkali‐catalysed biphenyl‐4,4′‐diol formaldehyde resin (BPFR) are synthesized. Glass fibre‐reinforced GA‐ER/BPFR composites are prepared. Graphene oxide (GO) is used to improve the mechanical and thermal properties of GA‐ER/BPFR composites. Dynamic mechanical properties and thermal, mechanical, and electrical properties of the composites with different GO content are characterized. The results demonstrate that GO can enhance the mechanical and thermal properties of the composites. The glass transition temperature, T_g, of the BPFR/GA‐ER/GO composites is 20.7°C higher than the pure resin system, and the 5% weight loss temperature, T_d5, is enhanced approximately 56.6°C. When the BPFR: GA‐ER mass ratio is at 4 : 6 and GO content is 1.0–1.2 wt %, the tensile and impact strengths of composites are 60.97 MPa and 32.08 kJ/m² higher than the pure resin composites, respectively. BPFR/GA‐ER composites have better mechanical properties, and can replace common BPA epoxy resins in the fabrication of composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42637.     

In situ development of bio‐based polyurethane‐blend‐epoxy hybrid materials and their nanocomposites with modified graphene oxide via non‐isocyanate route

We developed a series of sunflower oil‐based non‐isocyanate polyurethane (NIPU)‐blend‐epoxy hybrid materials (HNIPUs) and their nanocomposites with amine‐functionalized graphene oxide (AF‐GO). Firstly, carbonated sunflower oil (CSFO) containing five‐membered cyclocarbonate groups was synthesized by the reaction of epoxidized sunflower oil with carbon dioxide (CO₂) at a pressure of 50 bar and temperature of 110 °C. Then, a series of HNIPUs were synthesized using a mixture of CSFO and a commercially available epoxy resin in various amounts (10, 20 and 30 wt% with respect to CSFO) using isophorone diamine as the curing agent. The HNIPU with 30 wt% epoxy showed the best mechanical properties. Finally, nanocomposites of 30 wt% HNIPU‐based composition were prepared with various amounts of AF‐GO (0.3, 0.6 and 1.0 wt%) and were characterized using Fourier transform infrared and ¹H NMR spectroscopies, X‐ray diffraction and scanning electron microscopy. These results emphasize the potentiality of this environmentally friendly approach for preparing renewable HNIPU and nanocomposite materials of high performances. © 2018 Society of Chemical Industry     

Plasma treatment‐induced fluorine‐functionalized multi‐walled carbon nanotubes to modify poly(ethylene terephthalate) obtained via in situ polymerization

The introduction of carbon nanotubes in a polymer matrix can markedly improve its mechanical properties and electrical conductivity, and much effort has been devoted to achieve homogeneous dispersions of carbon nanotubes in various polymers. Our group previously performed successfully fluorine‐grafted modification on the sidewalls of multi‐walled carbon nanotubes (MWCNTs), using homemade equipment for CF₄ plasma irradiation. As a continuation of our previous work, in the present study CF₄ plasma‐treated MWCNTs (F‐MWCNTs) were used as a nanofiller with poly(ethylene terephthalate) (PET), which is a practical example of the application of such F‐MWCNTs to prepare polyester/MWCNTs nanocomposites with ideal nanoscale structure and excellent properties. As confirmed from scanning electron microscopy observations, the F‐MWCNTs could easily be homogeneously dispersed in the PET matrix during the in situ polymerization preparation process. It was found that a very low content of F‐MWCNTs dramatically altered the crystallization behavior and mechanical properties of the nanocomposites. For example, a 15 °C increase in crystallization temperature was achieved by adding only 0.01 wt% F‐MWCNTs, implying that the well‐dispersed F‐MWCNTs act as highly effective nucleating agents to initiate PET crystallization at high temperature. Meanwhile, an abnormal phenomenon was found in that the melt point of the nanocomposites is lower than that of the pure PET. The mechanism of the tailoring of the properties of PET resin by incorporation of F‐MWCNTs is discussed, based on structure–property relationships. The good dispersion of the F‐MWCNTs and strong interfacial interaction between matrix and nanofiller are responsible for the improvement in mechanical properties and high nucleating efficiency. The abnormal melting behavior is attributed to the recrystallization transition of PET occurring at the early stage of crystal melting being retarded on incorporation of F‐MWCNTs. Copyright © 2009 Society of Chemical Industry     

Octa(aminophenyl) polyhedral oligomeric silsesquioxane/boron‐containing phenol–formaldehyde resin nanocomposites: Synthesis,cured, and thermal properties

Octa(aminophenyl) polyhedral oligomeric silsesquioxane (OAP‐POSS) and boron‐containing phenol‐formaldehyde resin (BPFR) were synthesized, respectively. The BPFR nanocomposites with different OAP‐POSS content (wt%) were prepared, and their properties were characterized. The results show that the thermal degradation process of this nanocomposites can be divided into three stages, and they are all following the first order mechanism. The residual ratio and thermal degradation activation energy E_a of 9 wt% OAP‐POSS/BPFR nanocomposites are both better than others and the E_a increase gradually in three stages, which is 93.3, 134.0, and 181.9 kJ mol⁻¹, respectively. Its residual ratio at 900°C is 36.48%. The mechanical loss peak temperature T_p is 228°C for 12 wt% OAP‐POSSS/BPFR nanocomposites, which is higher 48°C than pure BPFR. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

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.     

Properties of a reactive‐graphitic‐carbon‐nanofibers‐reinforced epoxy

Our previous studies showed that herringbone graphitic GNFs surface‐derivatized with reactive linker molecules bearing pendant primary amino functional groups capable of binding covalently to epoxy resins. Of special importance, herringbone GNFs derivatized with 3,4′‐oxydianiline (GNF‐ODA) were found to react with neat butyl glycidyl ether to form mono‐, di‐, tri‐, and tetra‐glycidyl oligomers covalently coupled to the ODA pendant amino group. The resulting reactive GNF‐ODA (butyl glycidyl)_n nanofibers, r‐GNF‐ODA, are especially well suited for reactive, covalent incorporation into epoxy resins during thermal curing. Based on these studies, nanocomposites reinforced by the r‐GNF‐ODA nanofibers at nanofiber loadings of 0.15–1.3 wt% were prepared. Flexural property of cured r‐GNF‐ODA/epoxy nanocomposites were measured through three‐point‐bending tests. Thermal properties, including glass transition temperature (T_g) and coefficient of thermal expansion (CTE) for the nanocomposites, were investigated using thermal mechanical analysis. The nanocomposites containing 0.3 wt% of the nanofibers gives the highest mechanical properties. At this 0.3‐wt% fiber loading, the flexural strength, modulus and breaking strain of the particular nanocomposite are increased by about 26, 20, and 30%, respectively, compared to that of pure epoxy matrix. Moreover, the T_g value is the highest for this nanocomposite, 14°C higher than that of pure epoxy. The almost constant change in CTEs before and after T_g, and very close to the change of pure epoxy, is in agreement with our previous study results on a chemical bond existing between the r‐GNF‐ODA nanofibers and epoxy resin in the resulting nanocomposites. POLYM. COMPOS., 28:605–611, 2007. © 2007 Society of Plastics Engineers     

Synergistic effect of three‐dimensional multi‐walled carbon nanotube–graphene nanofiller in enhancing the mechanical and thermal properties of high‐performance silicone rubber

The homogeneous dispersion of nanofillers and filler–matrix interfacial interactions are important factors in the development of high‐performance polymer materials for various applications. In the present work, a simple solution‐mixing method was used to prepare multi‐walled carbon nanotube (MWCNT)–graphene (G) (3:1, 1:1, 1:3) hybrids followed by their characterization through wide‐angle X‐ray diffraction, transmission electron microscopy and thermogravimetric analyses. Subsequently, MWCNT–G (1:1) hybrid was used as reinforcing filler in the formation of silicone rubber (VMQ) nanocomposites by solution intercalation, and their morphology and properties were investigated. Our findings showed that MWCNT–G (0.75 wt%)/VMQ composite exhibited significant improvements in tensile strength (110%) and Young's modulus (137%) compared to neat VMQ. The thermal stability of MWCNT–G (1 wt%)/VMQ was maximally improved by 154 °C compared to neat VMQ. Differential scanning calorimetry demonstrated the maximum improvement of glass transition temperature (4 °C), crystallization temperature (8 °C) and melting temperature (5 °C) for MWCNT–G (1 wt%)/VMQ nanocomposite with respect to neat VMQ. Swelling measurements confirmed that the crosslink density and solvent resistance were a maximum for hybrid nanocomposites. Such improvements in the properties of MWCNT–G/VMQ nanocomposites could be attributed to a synergistic effect of the hybrid filler. © 2013 Society of Chemical Industry     

Preparation and properties of cyclic olefin copolymers multiwalled carbon nanotube nanocomposites

Nanocomposites of cyclic olefin copolymer (COC) and two types of multiwalled carbon nanotubes (MWCNTs) with different aspect ratios were prepared. The morphology, thermal behavior, and electrical conductivity of the nanocomposites were investigated by scanning electron microscopy, differential scanning calorimetry, thermal gravimetric analysis, and the DC conductivity measurement. It was found that the developed nanocomposite preparation method resulted in good nanotubes dispersion in the polymer matrix for both types of MWCNTs. No appreciable differences in glass transition temperatures were observed between the pure COC and nanocomposites. On the other hand, CNTs significantly improved the thermo‐oxidative stability of the COC. The nanocomposites showed significant delay in onset of degradation and the degradation temperature was ～ 40°C higher than that of the pure COC. The nanocomposites also showed substantially higher DC conductivity, which increased with the nanotube concentration and aspect ratio. An increase of DC electrical conductivity over 10⁹ times can be achieved by the addition of 2 wt % CNTs. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Polypropylene nanocomposites with oxo‐degradable pro‐oxidant: Mechanical,thermal, rheological,and photo‐degradation performance

The objective of the study was to generate degradable polypropylene nanocomposites by incorporation of pro‐oxidant and different fillers like silica, silicate, and thermally reduced graphene. Graphene‐based composites exhibited higher crystallinity attributed to better dispersion and high aspect ratio platelets. Graphene composites with 2.5% additive content significantly enhanced the peak degradation temperature to 464°C as compared to 448°C for pure polymer. The processing conditions used for the nanocomposite generation were optimum as a uniform distribution of filler particles (or platelets) was observed in the PP matrix. The tensile modulus of the graphene composite with 2.5% additive content was 80% higher than pure PP, as compared to 60 and 30% for silicate and silica composites, respectively. Similarly, the storage modulus of the graphene nanocomposite with 1% additive content had 30% increment at 40°C as compared to pure PP. PP‐additive blends as well as PP nanocomposites with silica and silicate were observed to attain 100% degree of embrittlement within 6 months of UV exposure at 30°C. Graphene composites, though, had delayed photo‐degradation due to UV absorption by the platelets and high aspect ratio platelets acting as oxygen barrier for PP matrix, but the pro‐oxidant was successful in attaining controlled degradation. POLYM. ENG. SCI., 56:1229–1239, 2016. © 2016 Society of Plastics Engineers     

Thermal stability of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)/modified montmorillonite bio‐nanocomposites

Poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P34HB)/modified montmorillonite (EMMT) bio‐nanocomposites were prepared via melt intercalation method. The thermal stability of the bio‐nanocomposites was investigated. The results showed that the decomposition temperature (T _5%) of P34HB/EMMT bio‐nanocomposite reached 271.4°C, 39.9°C higher than that of pure P34HB. The remarkable thermal stability enhancement was presumably originated from the uniform dispersion of EMMT in the matrix and intercalated structures of P34HB/EMMT bio‐nanocomposites, which was related to the increased compatibility of EMMT and P34HB caused by the ester group in EMMT. TGA‐FTIR analysis on the thermal degradation procedures of the bio‐nanocomposites manifested that the introduction of EMMT did not alter the degradation mechanism of P34HB. However, the intercalated structures hindered the mobility of P34HB macromolecular and slowed down the decomposing process of P34HB. POLYM. COMPOS., 38:673–681, 2017. © 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.     

Effects of silica nanoparticles on tribology performance of poly(Epoxy Resin‐Bismaleimide)‐based nanocomposites

Introduction of small nanoparticles into polymer matrix increases the mechanical, tribological, and thermal properties of nanocomposites. In this study, poly(epoxy resin‐bismaleimide‐diaminodiphenylmethane) (EP‐BMI‐DDM) copolymers filled with silica nanoparticles (SNPs) were successfully fabricated through in situ suspension polymerization. To enhance the interfacial adhesion of silica particles to the polymer matrix, the nanoparticles were organo‐modified by silane coupling agent. Results of tensile strength test revealed that increased toughness of the composites was attributed to the microcavitations induced by organo‐modified SNPs (OSNPs). Proper loadings of OSNPs can play a critical role in antifriction performance, with optimal friction coefficient of 0.17 (2 wt% OSNPs content). Thermostabilities of the nanocomposites were characterized by differential thermal gravimetric analysis. At the maximum rate of weight loss of EP‐BMI‐DDM/3 wt% OSNP, the temperature measured 452°C, which is 52°C higher than that of pure EP‐BMI‐DDM copolymers (400°C). The produced nanocomposites feature good thermostability and self‐lubrication can be widely used as wearable material under severe working conditions with higher temperature. POLYM. ENG. SCI., 59:274–283, 2019. © 2018 Society of Plastics Engineers     

Nanocomposite films of poly(vinylidene fluoride) filled with polyvinylpyrrolidone‐coated multiwalled carbon nanotubes: Enhancement of β‐polymorph formation and tensile properties

To improve interactions between carbon nanotubes (CNTs) and poly(vinylidene fluoride) (PVDF) matrix, multiwalled CNTs (MWCNTs) were successfully coated with amphiphilic polyvinylpyrrolidone (PVP) using an ultrasonication treatment performed in aqueous solution. It was found that PVP chains could be attached noncovalently onto the nanotubes' surface, enabling a stable dispersion of MWCNTs in both water and N,N‐dimethylformamide. PVP‐coated MWCNTs/PVDF nanocomposite films were prepared by a solution casting method. The strong specific dipolar interaction between the PVP's carbonyl group (C?O) and the PVDF's fluorine group C?F₂ results in high compatibility between PVP and PVDF, helping PVP‐coated MWCNTs to be homogenously dispersed within PVDF. Fourier transform infrared and X‐ray diffraction characterization revealed that the as‐prepared nanocomposite PVDF films exhibit a purely β‐polymorph even at a very low content of PVP‐wrapped MWCNTs (0.1 wt%) while this phase is totally absent in the corresponding unmodified MWCNTs/PVDF nanocomposites. A possible mechanism of β‐phase formation in PVP‐coated MWCNTs/PVDF nanocomposites has been discussed. Furthermore, the tensile properties of PVDF nanocomposites as function of the content in PVP‐coated MWCNTs were also studied. Results shows that the addition of 2.0 wt% of PVP‐coated MWCNTs lead to a 168% increase in Young's modulus and a 120% in tensile strength. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Effects of epoxy resin‐modified zinc‐ion‐coated nanosilica on structural,thermal and dynamic mechanical properties of propylene‐ethylene copolymer

This paper reports a comparative study of propylene–ethylene copolymer (EP) nanocomposites synthesized using zinc‐ion (Zn²⁺)‐coated nanosilica (ZNS) and the diglycidyl ether of bisphenol‐A (DGEBA, an epoxy resin)‐modified zinc‐ion‐coated nanosilica (EZNS) as nanofillers. These nanocomposites were prepared using the ‘melt mixing’ method at a constant loading level of 2.5 wt%. This loading level is much lower than that used for fillers in conventional composites. The EP nanocomposites were characterized using wide‐angle X‐ray diffractometer (WAXD), a thermo gravimetric analyzer (TGA), a differential scanning calorimeter (DSC), a dynamic mechanical analyzer (DMA) and scanning electron microscopy (SEM). DMA results showed a higher storage modulus for EP‐epoxy‐modified Zn²⁺‐coated nanosilica nanocomposite (EP‐EZNS) with respect to EP and EP‐Zn²⁺‐coated nanosilica nanocomposite (EP‐ZNS). In addition, TGA thermograms showed an increase in degradation temperature of EP in the presence of EZNS. Copyright © 2006 Society of Chemical Industry     

Enhanced coating properties of Ni‐La‐ferrites/epoxy resin nanocomposites

Coating properties of new Ni‐La‐ferrites/epoxy resin nanocomposites has been achieved using modified epoxy resin with Ni‐La‐ferrite nanoparticles in the form of NiLaFeO₄/epoxy nanocomposites using electrochemical impedance and sorption of water measurements. Simple solution method with ultrasonic assistance was used in the preparation of the new nanocomposites in situ while epoxy resin was prepared. The new materials were characterized by X‐ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy, and electrochemical impedance spectroscopy. The nanocrystalline NiLaFeO₄ showed a good distribution and high compatibility forming strong interfacial adhesion within the epoxy matrix. Furthermore, it had ability to facilitate thermal degradation of the epoxy resin nanocomposite due to its catalytic effect. Temperatures at 10, 25, 50% weight loss and the normalized solid residue left at 500°C (NR500) were measured. The presence of nanocrystalline NiLaFeO₄ stabilized the char residue obtained at 500°C in the resulting composites. The Ni‐La‐ferrite nanoparticles decreased water sorption (WS) of the epoxy. The 5% and 10%‐ Ni‐La‐ferrites/epoxy nanocomposites showed least amount of WS among the epoxy composites. The 5 and 10% Ni‐La‐ferrite nanoparticles contents enhanced significantly the barrier behavior of the epoxy as coating of stainless steel. POLYM. COMPOS., 36:1875–1883, 2015. © 2014 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     

Electrical and rheological percolation in poly(vinylidene fluoride)/multi‐walled carbon nanotube nanocomposites

Nanocomposites of poly(vinylidene fluoride) (PVDF) and multi‐walled carbon nanotubes (MWCNTs) were prepared through melt blending in a batch mixer (torque rheometer equipped with a mixing chamber). The morphology, rheological behavior and electrical conductivity were investigated through transmission electron microscopy, dynamic oscillatory rheometry and the two‐probe method. The nanocomposite with 0.5 wt% MWCNT content presented a uniform dispersion through the PVDF matrix, whereas that with 1 wt% started to present a percolated network. For the nanocomposites with 2 and 5 wt% MWCNTs the formation of this nanotube network was clearly evident. The electrical percolation threshold at room temperature found for this system was about 1.2 wt% MWCNTs. The rheological percolation threshold fitted from viscosity was about 1 wt%, while the threshold fitted from storage modulus was 0.9 wt%. Thus fewer nanotubes are needed to approach the rheological percolation threshold than the electrical percolation threshold. Copyright © 2010 Society of Chemical Industry