Liudmyla Karachevtseva; Mykola Kartel; Wang Bo; Yurii Sementsov; Viacheslav Trachevskyi; Oleg Lytvynenko; Volodymyr Onyshchenko
Abstract
Carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. The possibilities to enhance the properties of nanostructured surfaces were demonstrated on “polymer-multiwall carbon nanotube” composites. Influence of sp < sup > 3 hybridization ...
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Carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. The possibilities to enhance the properties of nanostructured surfaces were demonstrated on “polymer-multiwall carbon nanotube” composites. Influence of sp < sup > 3 hybridization bonds on polymer crystallization and strengthening was investigated in composite films of polyethyleneimine, polypropylene and polyamide with multiwall carbon nanotubes. It was established that the effective way to enhance the strength properties of “polymer-multiwall carbon nanotube” composites is the composite crystallization and sp < sup > 3 C-C tetrahedrons organization between nanotubes supported by resonance γω(C?)? and γω(CH2) vibrations in the intrinsic electric field 6×10 3 V/cm between nanotube and polymer matrix. Tensile strength for polyamide-6 composites at 0.25% CNT increases 1.7 times and tensile deformation – 2.3 times.
C. Vibha; P. P. Lizymol
Abstract
Inorganic-organic hybrid resins revolutionarize the biomedical field by virtue of its versatility. In this work, bioactive inorganic-organic hybrid resins containing mixture of alkoxides of calcium/magnesium/zinc with polymerizable tetramethacrylate groups was synthesized using 1,3-bis methacryloxy 2-(trimethoxy ...
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Inorganic-organic hybrid resins revolutionarize the biomedical field by virtue of its versatility. In this work, bioactive inorganic-organic hybrid resins containing mixture of alkoxides of calcium/magnesium/zinc with polymerizable tetramethacrylate groups was synthesized using 1,3-bis methacryloxy 2-(trimethoxy silyl propoxy) propane as the precursor. We optimised the processing parameters by investigating the influence of pH of the medium used for the hydrolysis of silane on molecular weight of the resultant resin obtained. Physico-mechanical properties including polymerisation shrinkage of photocured composites prepared from novel inorganic-organic hybrid resins were evaluated and compared. The resin hydrolysed at pH 2 have low molecular weight with high filler loading capacity (325 phr) than the one hydrolysed at pH 10. Photocured polymeric composite fabricated from resin hydrolysed at pH 2 showed lower polymerisation shrinkage, better depth of cure, good diametral tensile strength, non-cytoxic to L929 fibroblasts with good cell viability and cell adhesion. This new biocompatible polymer with low polymerisation shrinkage stands as a potent candidate in biomedical applications, especially in the field of dental, orthopaedic and coating applications.
Burak Caglar; Justin Richards; Peter Fischer; Jens Tuebke
Abstract
In this study polypropylene (PP) based conductive composites and metal doped diamond like carbon (DLC) coated metallic substrates are studied as alternative bipolar materials for all-vanadium redox flow battery (VRFB). Graphite and carbon nanotube (CNT) filled PP based bipolar plates were produced via ...
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In this study polypropylene (PP) based conductive composites and metal doped diamond like carbon (DLC) coated metallic substrates are studied as alternative bipolar materials for all-vanadium redox flow battery (VRFB). Graphite and carbon nanotube (CNT) filled PP based bipolar plates were produced via twin-screw co-rotating extruder and injection molding. Addition of 3 wt. % CNTs into highly filled graphite-PP matrix increased in-plane and through-plane electrical conductivities from 10 S/cm to 50 S/cm and from 2 S/cm to 10 S/cm respectively. PP composites with 78 wt. % graphite and 2 wt. % CNT filling ratio showed flexural strength value of 48,01 MPa. Produced bipolar plates were examined with galvanostatic charge-discharge test in a single-cell VRFB. Energy efficiency of 85,43 % at 25 mA/cm2 and discharge power density of 78,48 mW/cm 2 at 75 mA/cm 2 were achieved and those values were found to be comparable with commercial bipolar plates. Titanium, vanadium, chromoium and tungsten doped diamond-like coating (DLC) films were coated on metallic substrates (e.g. stainless steel 1.4301 and titanium alloy 3.7165) by a physical vapor deposition. The metallic dopant is necessary to achieve high conductivities in the order of ~100 S/cm. The values range from 0.5 to 35 S/cm for in-plane and from 10 to 110 S/cm for through-plane. The hydrogen evolution reaction (HER) and the anodic corrosions stability in 2 molar sulfuric acid constituted the main focus area for our investigations on metallic bipolar plates. An interesting material for coated metallic bipolar plate is the 10 µm Ti-DLC on 1.4301 which exhibits the highest hydrogen evolution overpotential of all investigated materials (710 mV µA/cm²). It also showed improved corrosion stability for anodic potentials.
Satnam Singh; Pardeep Kumar;S.K. Jain
Abstract
Composites are one of the most advanced and adaptable engineering materials. The strength of any composite depends upon volume/weight fraction of reinforcement, L/D ratio of fibers, orientation angles and other factors. The present work focuses on determination of mechanical properties of pure epoxy ...
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Composites are one of the most advanced and adaptable engineering materials. The strength of any composite depends upon volume/weight fraction of reinforcement, L/D ratio of fibers, orientation angles and other factors. The present work focuses on determination of mechanical properties of pure epoxy and random oriented glass fiber (mat) reinforced epoxy at 10% and 20% weight fractions of glass fibers. The test specimens were prepared and tested according to ASTM standards. The experimental results revealed that with increase in weight fraction of reinforcement, the tensile strength and flexural strength increased by 14.5 % and 123.65% for 20 % glass reinforced composites over pure epoxy. The numerical results obtained were in good agreement to the experimental results. However increased reinforcement increases the brittleness of material which may results in low impact strength. This study further can be used to optimize the weight fraction of glass fibers, to achieve a combination of strength without compromising the impact strength of composites.
Ranjana Singh; S. G. Kulkarni; N. H. Naik
Abstract
A number of nanocomposites have been synthesized biomimetically by embedding various transition metal salts in polyvinyl alcohol (PVA) as the preorganised matrix. The metal salts were reduced to metallic form using aqueous sodium borohydride solution. In the present paper, very comprehensive studies ...
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A number of nanocomposites have been synthesized biomimetically by embedding various transition metal salts in polyvinyl alcohol (PVA) as the preorganised matrix. The metal salts were reduced to metallic form using aqueous sodium borohydride solution. In the present paper, very comprehensive studies on thermal decomposition behavior of these composites have been carried out using thermogravimetric and differential scanning calorimetric studies. The transition metal salts/ metals based composites exhibit increased thermal stability as indicated by shift in the decomposition temperature of pure PVA. The DSC data show increase in glass transition temperature of all composites, except the one containing iron, in comparison with neat PVA.The improvement in the thermal stability is explained in terms of decrease in the segmental mobility of polymer chains due to entrapment of metal salt / metal forming a complex with the hydroxyl group of the polymer chains and thus decreasing heat transfer process for decomposition of polymer composites.
M. Roy; J. Bajpai;A. K. Bajpai; R. G. Mahloniya
Abstract
Novel electrically conducting nanocomposite materials comprising of poly (pyrrole) (PPy) nanoparticles dispersed homogeneously in a poly (vinyl alcohol)-g-poly (2-acrylamido-2-methyl-1-propanesulphonic acid-co-acrylonitrile) matrix were prepared by in situ polymerization of pyrrole. Radiation shielding ...
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Novel electrically conducting nanocomposite materials comprising of poly (pyrrole) (PPy) nanoparticles dispersed homogeneously in a poly (vinyl alcohol)-g-poly (2-acrylamido-2-methyl-1-propanesulphonic acid-co-acrylonitrile) matrix were prepared by in situ polymerization of pyrrole. Radiation shielding potential of so designed polypyrrole based nanocomposites was studied by exposure of polymer materials to gamma radiation under varying experimental conditions and structural and morphological changes in irradiated materials were examined by FTIR and SEM techniques.
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