Study on the Effect of Polypyrrole and Polypyrrole/Graphene Oxide Nanoparticles on the Microstructure,Electrical and Tensile Properties of Polypropylene Nanocomposites

In this article Polypropylene/Polypyrrole (PP/PPy) and Polypropylene/polypyrrole-graphene oxide (PP/PPy-GO) nanocomposites were prepared by melt mixing. PPy nanoparticles and PPy-GO nanocomposite were prepared by chemical polymerization and served as nanofillers. FTIR, XRD and SEM analysis were used for the characterization of PPy and PPy-GO composites. The effects of PPy and PPy-GO loading level on the morphology, tensile and electrical properties of PP-based nanocomposites were examined. It was found that the Young's modulus and tensile strength increased with the increase of nanofiller content. Tensile results also showed that PPy-GO composite significantly affected the mechanical properties of PP based nanocomposites compared to the PPy nanoparticles. It was observed that the addition of 1% wt. PPy-GO into PP, increased the Young's modulus about 30% compared as with pure PP. Electrical conductivity measurements showed that conductivity of PP nanocomposites increased up to 1 × 10^?3 S/cm for PP/PPy-GO nanocomposites. It was also observed that PP-g-MA improved the distribution of PPy and PPy-GO nanocomposites and affected the morphology, electrical and mechanical properties of PP-based nanocomposites.     

Thermal and mechanical properties of melt processed intercalated poly(methyl methacrylate)–organoclay nanocomposites over a wide range of filler loading

BACKGROUND: Poly(methyl methacrylate) (PMMA)–organoclay nanocomposites with octadecylammonium ion‐modified montmorillonite, prepared via melt processing, over a wide range of filler loading (2–16 wt%) were investigated in detail. These hybrids were characterized for their dispersion structure, and thermal and mechanical properties, such as tensile modulus (E), break stress (σ_brk), percent break strain (ε_brk) and ductility (J), using wide‐angle X‐ray diffraction, transmission electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile and impact tests. RESULTS: Intercalated nanocomposites were formed even in the presence of 16 wt% clay (high loading) in PMMA matrix. PMMA intercalated into the galleries of the organically modified clay, with a change in d‐spacing in the range 11–16 Å. TGA results showed improved thermal stability of the nanocomposites. The glass transition temperature (T_g) of the nanocomposites, from DSC measurements, was 2–3 °C higher than that of PMMA. The ultimate tensile strength and impact strength decreased with increasing clay fraction. Tensile modulus for the nanocomposites increased by a significant amount (113%) at the highest level of clay fraction (16 wt%) studied. CONCLUSION: We show for the first time the formation of intercalated PMMA nanocomposites with alkylammonium‐modified clays at high clay loadings (>15 wt%). Tensile modulus increases linearly with clay fraction, and the enhancement in modulus is significant. A linear correlation between tensile strength and strain‐at‐break is shown. Thermal properties are not affected appreciably. Organoclay can be dispersed well even at high clay fractions to form nanocomposites with superior bulk properties of practical interest. Copyright © 2007 Society of Chemical Industry     

Synthesis and thermal characterization of phenolic resin/silica nanocomposites prepared with high shear rate‐mixing technique

In this research the possibility to produce nanosilica/phenolic nanocomposites by means of a simple low labor cost mechanical approach was investigated. A commercial compatibilized nanosilica was selected as a filler and a resol diluted in methanol as a matrix. The morphology of the produced nanocomposites were studied by means of Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), whereas thermogravimetric analysis (TGA) was used to study the thermal stability of the nanocomposites. The post burning morphology of samples was also investigated. A rheological characterization was also carried out. The results of such study showed that it was possible to obtain a good degree of dispersion and distribution of the nanosilica particles, indicating that the proposed process could be successfully adopted as an alternative approach to sol‐gel techniques. Thermogravimetric analyses showed that all the produced nanocomposites exhibited a better thermal stability than the pristine matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Poly(methyl methacrylate) nanocomposites based on graphene oxide: a comparative investigation of the effects of surface chemistry on properties and foaming behavior

The effects of oxygen functional groups and alkyl chains at the surface of graphene oxide (GO) on the thermal stability, mechanical properties and foaming behavior of poly(methyl methacrylate) (PMMA) nanocomposites were investigated. Alkyl‐functionalized GO (GO‐ODA) was prepared by grafting octadecylamine (ODA) on the surface of GO. PMMA/GO and PMMA/GO‐ODA nanocomposite were obtained by solution blending and were foamed using supercritical carbon dioxide (scCO₂). GO‐ODA, with the presence of alkyl chains, showed a better dispersion capability in PMMA matrix than GO with a large amount of oxygen functional groups. In addition, the good dispersion capability increased thermal stability and mechanical strength. In comparison with PMMA/GO samples foamed at 70 °C, PMMA/GO‐ODA nanocomposite foams displayed improved cell structures with higher cell density, smaller cell size and more homogeneous cell size distribution, which results from the strong heterogeneous nucleation due to alkyl chains on the GO surface. The foaming behaviors became more complicated at 80 °C as the GO might be intercalated and exfoliated with the aid of scCO₂, thus further enhancing the heterogeneous nucleation during the foaming process. The results indicated that the surface chemistry of GO was closely related to the properties and foaming behavior of the nanocomposites. © 2016 Society of Chemical Industry     

Impact of synergism of LDH with PNCC on the thermal and mechanical properties of polyester nanocomposites

ABSTRACT

Present study investigates, the synergistic effect of Precipitated Nano Calcium Carbonate with Layered Double Hydroxides (LDHs) on thermal and mechanical properties of unsaturated polyester resin. A polyester-LDH-PNCC nanocomposite was prepared using “slurry-compounding” method. Meanwhile, PNCC was prepared by in-situ deposition (matrix-mediated growth and controlled) technique, crystal dimension of PNCC was estimated by using Transmission Electron Microscope (TEM). Surface morphology and mechanical properties were studied by using Field Emission Scanning Electron Microscopy (FESEM) and Universal Tensile Machine (UTM) respectively. Wide angle X-ray diffraction (WAXD) study revealed the formation of polyester nanocomposites. The nanocomposites showed better thermal and mechanical properties than that of the unmodified polyester resin, thus, synergism of LDH-PNCC influenced thermal and mechanical properties of polyester nanocomposites.     

Effect of graphene oxide on the properties of compatibilized polypropylene/ethylene-propylene-rubber blend

In this work, the effect of graphene oxide (GO) and its derivatives on the mechanical, thermal and morphological properties of nanocomposites based on polypropylene/ethylene-propylene rubber (PP/EPR) were investigated. In order to achieve a better dispersion of the nanofiller and to enhance its interaction with the polymer matrix, amine and alcohol grafted polypropylene were used as compatibilizers. These compatibilizers were synthesized by the reaction of polypropylene-grafted anhydride maleic (PP-g-MAH) with 1,12-dodecanediamine and 1,12-dodecanediol, respectively in the presence of dicumyl peroxide (DCP) by melt mixing. The nanocomposites were prepared via melt blending masterbatch process using Brabender mixer. The addition of functionalized GO and compatibilizers improved the tensile strength and Young’s modulus of PP/EPR nanocomposite. While the elongation and Izod impact strength were adversely affected. Furthermore, the TGA analysis showed that the incorporation of GO and compatibilizers improve significantly the thermal stability. SEM micrographs of the fractured surfaces of the nanocomposites revealed a good dispersion of functionalized GO in the polymer matrix.     

A study on the properties of PMMA/silica nanocomposites prepared via RAFT polymerization

A number of batch polymerizations were performed to study the effect of pristine nanoparticle loading on the properties of PMMA/silica nanocomposites prepared via RAFT polymerization. In order to improve the dispersion of silica nanoparticles in PMMA matrix, the silanol groups of the silica are functionalized with methyl methacrylate groups and modified nanoparticles were used to synthesize PMMA/modified silica nanocomposites via RAFT polymerization. Prepared samples were characterized by thermogravimetric analysis (TGA), dynamic light scattering (DLS), dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). According to results, introduction of modified nanoparticles results in better thermal and mechanical properties than those of pristine nanoparticles. Also, surface modification and increasing silica nanoparticles result in variation of thermal degradation behavior of nanocomposites. The best improvement of mechanical and thermophysical properties is achieved for nanocomposites containing 7 wt. % silica nanoparticles.     

Impact of various oxidation degrees of graphene oxide on the performance of styrene–butadiene rubber nanocomposites

In this work, graphene oxide (GO) with various oxidation degrees were synthesized by adjusting the dosage of oxidation agent based on a modified Hummers' method, and were then used for the fabrication of the styrene–butadiene rubber (SBR)/GO nanocomposites through latex coagulation method, followed by a high‐temperature cure process. The vulcanization characteristics, thermal stability, mechanical properties, thermal conductivity as well as solvent resistance of SBR/GO nanocomposites were investigated. The results indicated that various surface structures of GO due to oxidation degrees may lead to different dispersion states of GO in the rubber matrix, and thus greatly influenced the cure rate, mechanical properties as well as thermal conductivity of SBR/GO nanocomposites. The optimal (moderate) oxidation degree of GO was achieved at the oxidation agent (KMnO₄)/graphite weight ratio 9/5, for which case the tensile strength, tear strength, and thermal conductivity of SBR/GO nanocomposites increased by 271.3%, 112.3%, and 28.6%, respectively, compared with those of neat SBR. In addition, the mentioned nanocomposites also showed the best solvent resistance in toluene. POLYM. ENG. SCI., 58:1409–1418, 2018. © 2017 Society of Plastics Engineers     

Preparation and Characterization of Polypropylene Nanocomposites Filled with Nano Calcium Phosphate

The synthesized nano calcium phosphate by matrix mediated growth and controlled technique was used as nanofiller in the preparation of polypropylene nanocomposites. Nanocomposites with different filler concentrations were prepared. The content of nano calcium phosphate was varied from 1 to 3 wt% in the preparation of PP nanocomposites. During preparation of nanocomposites shear rate was varied by means of increase in rpm, i.e., 60, 70, 80 and 90 with the help of Brabender Plastograph and the effect of shear rate was studied with respective to mechanical and thermal properties of composites. The comprehensive evaluation of the PP nanocomposites filled with nano calcium phosphate was done to observe the substantial improvement in the performance properties. The mechanical and thermal properties were determined by Universal Testing Machine (UTM) and Thermogravimetric Analyzer (TGA), respectively. The morphology of the fracture surfaces of the prepared PP nanocomposites filled with nano calcium phosphate was studied by Scanning Electron Microscopy (SEM).     

Impact of blend ratio on the properties of graphene oxide‐filled carboxylated acrylonitrile–butadiene rubber/styrene–butadiene rubber blends

Carboxylated acrylonitrile–butadiene rubber (XNBR) and styrene–butadiene rubber (SBR) composites with 3 phr (parts per hundred rubber) graphene oxide (GO) were prepared using a latex mixing method. Effects of XNBR/SBR blend ratios on the mechanical properties, thermal conductivity, solvent resistance and thermal stability of the XNBR/SBR/GO nanocomposites were studied. The tensile strength, tear strength, thermal conductivity and solvent resistance of the XNBR/SBR/GO (75/25/3) nanocomposite were significantly increased by 86, 96, 12 and 21%, respectively, compared to those of the XNBR/SBR (75/25) blend. The thermal stability of the nanocomposite was significantly enhanced; in other words, the temperature for 5% weight loss and the temperature of the maximal rate of degradation process were increased by 26.01 and 14.97 °C, respectively. Theoretical analysis and dynamic mechanical analysis showed that the GO tended to locate in the XNBR phase, which led to better properties of the XNBR/SBR/GO (75/25/3) nanocomposite. © 2017 Society of Chemical Industry     

Chemically modified graphene oxide/polybenzimidazobenzophenanthroline nanocomposites with improved electrical conductivity

Graphene/polybenzimidazobenzophenanthroline nanocomposites were prepared through the liquid-phase exfoliation of graphene oxide (GO) and reduced graphene oxide (rGO) in methanesulfonic acid with subsequent solution mixing. Various chemical and combined chemical-thermal methods were examined to be effective for producing rGO with highly graphitic structure and excellent electrical conductivity. Raman and X-ray photoelectron spectroscopy showed higher degree of reduction of the GO with the combined chemical-thermal method compared to other chemical reduction processes. Structural characterization of the nanocomposites by X-ray diffraction, scanning electron microscopy and transmission electron microscopy showed good exfoliation and dispersion of both GO and rGO fillers in the polymer matrix. The thermogravimetric analysis found that the nanocomposites with rGO have higher onset and maximum weight loss temperatures than those with GO. Compared with the pure polymer, the electrical conductivity of the nanocomposites containing 10 wt% GO and GO reduced by the combined chemical-thermal treatment showed a remarkable increase by four and seven orders of magnitude, respectively. Long-term in-situ thermal reduction was performed to further improve the conductivities of the nanocomposites.     

Compatibilised LDPE/LLDPE/nanoclay nanocomposites: I. Structural,mechanical, and thermal properties

Nanocomposites of LDPE/LLDPE/nanoclay have been prepared using a lab‐scale co‐rotating twin screw extruder. Using XRD, tensile testing, AFM, TGA, effects of some material properties and one processing parameter on mechanical and thermal properties of the prepared nanocomposites were evaluated. Tensile properties indicated that all the prepared nanocomposites exhibited a significant improvement in elastic modulus and toughness compared to pristine LDPE/LLDPE blends of the same composition. Thermal stability of nanocomposites in the air and nitrogen atmosphere was improved. XRD patterns and AFM micrographs showed semi‐exfoliated and intercalated microstructures for the prepared nanocomposites with different orders of mixing.     

Highly filled multilayer thermoplastic/graphene conducting composite structures with high strength and thermal stability for electromagnetic interference shielding applications

Polyvinyl chloride (PVC)/graphene and poly(methyl methacrylate) (PMMA)/graphene nanocomposites were made by solution casting technique with graphene weight fractions of 1, 5, 10, 15, and 20%. Multilayer structures of the composites were made by hot compression technique to study their electromagnetic interference shielding effectiveness (EMI SE). Tensile strength, hardness, and storage modulus of the nanocomposites were studied in relation with graphene weight fraction. There has been a substantial increase in the electrical conductivity and EMI SE of the composites with 15–20% filler loading. Differential thermal analysis of the composites shows improved thermal stability with an increase in graphene loading. PMMA/graphene composites have better thermal stability, whereas PVC/graphene composites have superior mechanical properties. About 2 mm thick multilayer structures of PMMA/graphene and PVC/graphene composites show a maximum EMI SE of 21 dB and 31 dB, respectively, in the X band at 20 wt % graphene loading. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47792.     

悬浮聚合聚甲基丙烯酸甲酯／蒙脱土纳米复合材料的制备及表征

采用悬浮聚合法制备了聚甲基丙烯酸甲酯／蒙脱土（PMMA/MMT）纳米复合材料，利用X射线衍射仪、透射电子显微镜和傅里叶变换红外光谱等手段表征了复合材料的结构，研究了不同改性剂对复合材料结构的影响。通过热重分析考察了复合材料的热性能。结果表明，通过悬浮聚合可以成功制备剥离型纳米复合材料，PMMA基体与MMT可以产生较强的相互作用。MMT的加入可以显著提高复合材料的热稳定性。当MMT含量为10％（质量分数，下同）时，PMMA的最大分解温度提高了15℃。     

The effect of graphene oxide on UV curing kinetics and properties of SU8 nanocomposites

In the present study SU8 nanocomposites were prepared by incorporating graphene oxide (GO ), and its effect on the UV curing kinetics, morphology, electrical, hardness and thermal properties of the nanocomposites were investigated at different loading levels of GO (0.1 ? 3 wt%). Studying the reaction kinetics of the UV curing process by means of real‐time infrared spectroscopy showed that the polymerization rate and the final conversion of epoxy groups was related to the loading level of GO in the nanocomposites. An autocatalytic kinetics model of the curing reaction confirmed the effect of GO nanoparticles on the curing rate constant (k ), the order of the initiation reaction (m ) and the ultimate conversion of the UV ‐cured nanocomposites. Appropriate experimental observations indicated that dispersion of GO within the resin plays a critical role on the cure kinetics and final conversion. The results of the kinetics modeling and morphological observations showed that the curing rate constant of the nanocomposites is highly dependent on the GO content and its dispersion state, indicating that GO prevents epoxy resin crosslinking by photoinitator deactivation. Moreover, oxygen functionalities, such as hydroxyl and carboxyl groups, on the surface of GO facilitate interfacial interactions between epoxy groups from the matrix and GO . Electrical conductivity measurements demonstrated that the UV ‐induced photo‐cured GO filled resins are conductive SU8 nanocomposites. It was observed that the thermal stability of the nanocomposites is enhanced due to the dispersion of GO in the matrix. Moreover, the microhardness analysis showed that addition of GO to neat SU8 increases the mechanical hardness of the nanocomposite. © 2016 Society of Chemical Industry     

Montmorillonite nanoclay filler effects on electrical conductivity,thermal and mechanical properties of epoxy‐based nanocomposites

Epoxy‐based nanocomposites with 2, 5, and 7 wt% of montmorillonite (MMT) nanoclay were prepared using high shear melt mixing technique. The microstructural features of the nanocomposites were investigated by transmission electron microscopy (TEM). The thermal and mechanical properties were measured using differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), and dynamic mechanical analyzer (DMA). Further, the effect of voltage, temperature, seawater aging on the electrical conductivity (σ_DC) of the nanocomposites was also measured. To understand the free volume behavior upon filler loading, and to observe the connectivity between microstructure and other properties, positron annihilation lifetime spectroscopy was used. The TEM results revealed that MMT nanoparticles were uniformly dispersed in the epoxy matrix. Experimental results showed that the inclusion of 2 wt% MMT nanofiller increased the T_g, electrical conductivity, thermal stability, modulus, free volume of the epoxy nanocomposite significantly. This is well explained from the results of T_g (DSC and DMA), thermal stability, TGA residue, free volume analysis, and electrical conductivity. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Thermal and mechanical properties of liquid silicone rubber composites filled with functionalized graphene oxide

To improve the thermal and mechanical properties of liquid silicone rubber (LSR) for application, the graphene oxide (GO) was proposed to reinforce the LSR. The GO was functionalized with triethoxyvinylsilane (TEVS) by dehydration reaction to improve the dispersion and compatibility in the matrix. The structure of the functionalized graphene oxide (TEVS‐GO) was evaluated by Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD), and energy dispersive X‐ray spectroscopy (EDX). It was found that the TEVS was successfully grafted on the surface of GO. The TEVS‐GO/LSR composites were prepared via in situ polymerization. The structure of the composites was verified by FTIR, XRD, and scanning electron microscopy (SEM). The thermal properties of the composites were characterized by TGA and thermal conductivity. The results showed that the 10% weight loss temperature (T₁₀) increased 16.0°C with only 0.3 wt % addition of TEVS‐GO and the thermal conductivity possessed a two‐fold increase, compared to the pure LSR. Furthermore, the mechanical properties were studied and results revealed that the TEVS‐GO/LSR composites with 0.3 wt % TEVS‐GO displayed a 2.3‐fold increase in tensile strength, a 2.79‐fold enhancement in tear strength, and a 1.97‐fold reinforcement in shear strength compared with the neat LSR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42582.     

Fabrication of polypyrrole/graphene oxide nanocomposites by liquid/liquid interfacial polymerization and evaluation of their optical,electrical and electrochemical properties

A novel route has been developed to synthesize polypyrrole (PPy)/graphene oxide (GO) nanocomposites via liquid/liquid interfacial polymerization where GO and initiator was dispersed in the aquous phase and the monomer was dissolved in the organic phase. The synthesized samples were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), ultraviolet–visible absorption (UV–vis), X-ray diffraction (XRD), electrochemical and electrical conductivity measurements. A good dispersion of the GO sheets within the PPy matrix was observed from the morphological analysis. The composites exhibited noticeable improvement in thermal stability and electrical conductivity in comparison to pure polypyrrole. The composites showed excellent electrochemical reversibility at the scan rate of 0.1 V/s and good cyclic stability even up to 100th cycle. Newly developed graphene oxide based polypyrrole composite could be applied in electrochemical energy storage device.     

Conductive,Gas Barrier,and Thermal Resistant Behavior of Poly (methyl methacrylate) Composite by Dispersion of ZrO2 Nanoparticles

Poly (methyl methacrylate)/zirconium dioxide (PMMA/ZrO₂) nanocomposites were prepared by the incorporation of ZrO₂ nanoparticles in various proportions (2, 4, 6, 8, and 10%) with PMMA matrix by in situ emulsifier-free emulsion polymerization technique. The structural property of PMMA/ZrO₂ nanocomposites was studied by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The thermal stability of PMMA/ZrO₂ nanocomposites was improved with increasing concentration of ZrO₂. The electrical conductivity of composites was measured as function of ZrO₂ concentration. The oxygen barrier properties of PMMA/ZrO₂ nanocomposites were measured by using gas permeameter.     

氢化丁腈橡胶/有机蒙脱土纳米复合材料的结构与性能

采用机械混炼法制备氢化丁腈橡胶／有机蒙脱土纳米复合材料，并对复合材料的微观结构及性能进行了研究。透射电镜和X衍射结果显示，制得一种剥离型纳米复合材料；与纯氢化丁腈硫化橡胶相比，氢化丁腈橡胶／有机蒙脱土纳米复合材料具有优良的力学性能，并且随蒙脱土含量的增加而提高；TGA结果显示，氢化丁腈橡胶／有机蒙脱土纳米复合材料的热稳定性能提高。