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MIT World Peace University

School of Polymer Engineering

Present study deals with the effect of variation in melt flow index (MFI) of maleic anhydride-grafted polypropylene (PP-g-MAH) as a polymeric compatibilizing agent on various properties of fly ash (FA)-filled polypropylene (PP) composites. The FA content was varied from 0 to 40 wt%. The effect of polymeric compatibilizing agents with different MFI and very high maleic anhydride (MAH) content on interfacial adhesion between filler and matrix and filler dispersion were studied. The mechanical and thermal properties of the composite material were evaluated, and the microstructure was investigated through scanning electron microscopy. The values of yield stress and breaking strength of compatibilized PP/PP-g-MAH/FA-based composites showed higher values compared to that of untreated FA-filled PP composites at corresponding filler content. Incorporation of FA into PP led to stiffer materials, as tensile modulus increased significantly. Tensile and impact properties varied with varying molecular weight of PP in PP-g-MAH and are essentially decided by wettability of the filler. It is also found that heat-deflection temperature and vicat softening point improved with the addition of FA filler. The use of PP-g-MAH as polymeric coupling agent provides improvement in mechanical and thermal properties of filled polymers. The higher effect of compatibilization is obtained using high-molecular-weight PP in PP-g-MAH as a polymeric compatibilizing agent and low-molecular-weight PP in PP-g-MAH resulted in better dispersion of FA in PP matrix. The overall results showed that FA dispersion and interfacial adhesion are greatly affected by the kind of PP-g-MAH. © The Author(s) 2013.

Engineering and Technology

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Journal of Thermoplastic Composite Materials

Studies on the effect of maleic anhydride-grafted polypropylene with different MFI on mechanical, thermal and morphological properties of fly ash-filled PP composites

Fly ash cenospheres are inexpensive, readily available from coal burning or heavy oil combustion, not an eco-friendly material. If ways can be found to use this, it will serve the twin purposes of facilitating applications for the ash bearing materials and at the same time reduce pollution. One way to achieve this task is to make ash-bearing composites having polymer matrices. The performance of filled polymers is generally determined on the basis of the interface attraction of filler and polymers. Fillers of widely varying particle size and surface characteristics are responsive to the interfacial interactions with the polymers. The present study deals with the effect of particle size (150 mesh, 100 mesh, and 300 mesh) variations in fly ash cenospheres, as a filler with different concentrations (0-40 wt%), on various properties of acrylonitrile butadiene styrene. The mechanical, thermal, and electrical properties of the composite material were evaluated, and the microstructure was investigated through scanning electron microscopy. The smaller particle size showed better properties in comparison with larger particle size. As increasing filler loading, the saturation level is influenced by the agglomeration of filler particles in the polymer matrix. Thus, the performance of polymer filled with fly ash cenosphere composites is the function of the particle size, the dispersion, and the interfacial interaction between the filler particles and the polymer matrix. © The Author(s) 2012.

Effect of particle size of fly ash cenospheres on the properties of acrylonitrile butadiene styrene-filled composites

In the attempt to make low cost conducting polymer composite materials for fuel cell / battery applications, polypropylene (PP) with graphite (Gr) and other carbon black/ nanotubes hybrid materials were investigated. The development of crystalline structure in polypropylene (PP) graphite composite was studied with respect to composition and processing conditions. The DSC and XRD data confirmed the preferential nucleation and beta crystalline phase formation for the binary PP-Gr composites. There was dramatic increase in the electrical conductivity by addition of small amount of thrid component (CNT <5%) to the binary PP-Gr composite even at low graphite loading of 10%. Impedance spectroscopy analysis showed that the interfacial capacitance, with the addition of 2.75 wt% CB in PP-7 wt% graphite, increases to 52 pF from 31 pF for PP-7 wt% graphite proving the occupation of CB particles in the interspaces of graphite particles. The results of electrical conductivity were correlated with the nucleation and crystallization of the beta phase of PP by graphite flakes leading to interfacial resistive layer in binary composites while suppression of these effects in the ternary composites.

Technical Proceedings of the 2013 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2013

Structure and Electrical Properties of Polypropylene-Graphite-Carbon black/ Nanotubes Hybrid Conducting Composites

Azo-bridged azole derivatives were designed and investigated in order to find comprehensive relationship between the structure and performance of nitrogen-rich energetic compounds. Density functional theory (DFT) was used to predict the optimized structures, heat of formation, and detonation properties. Introduction of the azido group greatly enhances the heat of formation of these derivatives due to the high energy contribution from the -N 3 group. The crystal density was predicted by using the DREIDING force field. The nitroazoles show higher densities than amino and azido derivatives and hence better detonation performance. Thermal stability was analyzed using bond dissociation energies of C-NO 2, C-NH 2, and C-N 3 bonds. Nucleus-independent chemical shifts (NICS) were calculated at the ring centers to find the stability via aromaticity. The sensitivity of the designed compounds were predicted on the basis of band gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital. The amino derivatives were found to be more stable and less sensitive than the designed compounds. © 2012 Copyright Taylor and Francis Group, LLC.

Journal of Energetic Materials

Quantum Chemical Studies on Energetic Azo-Bridged Azoles

The synthesis of nano particulate CaCO3, Fe2O 3 and BaSO4 was carried out by green route using the Polymer Mediated Growth (PMG) technique. Large quantities of these nano particles up to few kilograms can be synthesized easily using the PMG method. This is also eco-friendly and green route since it is low temperature aqueous method, does not use toxic chemicals or consume high energy/ electrical power. The particles were characterized by XRD, SEM and TEM to confirm their structure and particle size at nano-levels. These were incorporated at 3-5 wt % in vinyl coatings using polyvinyl acetate or polyvinyl butyral which were coated on mild steel substrates. The corrosion protection was studied using electrochemical impedance spectroscopy (EIS) and monitoring the impedance, open circuit potential, phase etc. over prolonged periods of 150 to 450 hrs at 45 C in saline conditions (3.5% NaCl solution) The nano-particle additives are seen to be 7 to 10 times superior to the commercial grades in corrosion protection. The corrosion protection efficiency of these nano-particle additives is seen to follow the order nano-CaCO3 &lt; nano-Fe2O3&gt; nano-BaSO4 in vinyl coatings.

Large scale eco-friendly synthesis of nanoparticulate fillers for corrosion resistant vinyl coatings

All polymer composites contain blends of two or three polymers of which the minor phase is in fibrous form and acts as the reinforcement for the material. In the present studies polypropylene (PP) with nylon (Ny) were compounded extruded and then molded at temperature close to nylon. Crystallization kinetics and structure devlopment was studied in the PP-Ny blends with composition. Nylon dispersed phase was found to nucleate PP giving rapid crystallization. There was extensive fibrous morphology and fiber diameter was dependent on composition. The tensile and impact strength were considerably improved by almost 1.5 to 2 times that of PP at certain concentrations of nylon. Thus, these blends behave as self reinforced composites due to the peculiar nanofibrous morphology getting developed during melt processing.

Novel in situ nano fibrous reinforced all polymer polypropylene-nylon composite

Conducting polypyrrole (PPy) thin-film electrodes were prepared by the electropolymerization of pyrrole on gold-coated glass plates. Films of various roughnesses were obtained by the variation of the scan rates during electropolymerization. These thin films were modified by doping with 6mM of the dopant NiCl 2. The surface morphology of the films was studied by scanning electron microscopy and atomic force microscopy (AFM), which suggested films prepared with a high scan rate were rougher in nature than the films produced with a low scan rate. The electrocatalytic reduction of nitrobenzene was carried out with these electrodes with the cyclic voltammetry technique in acetonitrile containing 0.1M HClO 4 as a supporting electrolyte. The various results obtained show that the conducting PPy thin-film electrodes were catalytically active toward the electroreduction process. The modified PPy film electrodes doped with NiCl 2 were more active toward nitrobenzene electroreduction than the PPy film alone. The results indicate that the roughness of the films played a very important role in determining their catalytic activity. The PPy films that were more rough in nature were catalytically more active than the smooth films; this may have been due to the availability of more reactive sites in the case of rough films. The apparent diffusion coefficients of the PPy film electrodes were also calculated. © 2012 Wiley Periodicals, Inc.

Journal of Applied Polymer Science

Effect of the surface roughness of conducting polypyrrole thin-film electrodes on the electrocatalytic reduction of nitrobenzene

Conducting polypyrrole electrodes were prepared by electrochemical polymerization of pyrrole on vacuum-metallized glass substrates. These electrodes were modified by doping with a range of metal halides as dopant ions having different electronegativity. Electrochemical reduction of nitrobenzene using these electrodes was studied by means of cyclic voltammetry technique in acetonitrile medium containing aqueous HClO4 (0.1M) as supporting electrolyte. It was found that the electronegativity of the dopant ion played a very important role in the electrocatalytic activity. Polypyrrole doped with nickel chloride gave the highest anodic current at the reduction potential of nitrobenzene. The results were explained on the basis of charge transfer efficiency at the electrode-electrolyte interface, which was associated with the acceptor state created by the dopant in the semi-conducting polymer. © 2010 Wiley Periodicals, Inc.

Dopant induced effect on electrocatalytic reduction of nitrobenzene using conducting polypyrrole thin film electrodes

Polyaniline (PANI) is one of the most extensively used conjugated polymers in the design of electrochemical sensors. In this study, we report electrochemical dye detection based on PANI for the adsorption of both anionic and cationic dyes from solution. The inherent property of PANI to adsorb dyes has been explored for the development of electrochemical detection of dye in solution. The PANI film was grown on electrode via electrochemical polymerization. The as grown PANI film could easily adsorb the dye in the electrolyte solution and form an insulating layer on the PANI coated electrode. As a result, the current intensity of the PANI film was significantly altered. Furthermore, PANI coated stainless steel (SS) electrodes show a change in the current intensity of Fe2+/Fe3+ redox peaks due to the addition of dye in electrolyte solution. PANI films coated on both Pt electrodes and non-expensive SS electrodes showed the concentration of dye adsorbed is directly proportional to the current intensity or potential shift and thus can be used for the quantitative detection of textile dyes at very low concentrations. © 2011 Elsevier B.V.

Synthetic Metals

Polyaniline modified electrodes for detection of dyes

Polypyrrole was chemically functionalized with phthalocyanine (FePcTSA) derivative. The modified polymer with varying contents of functional material is synthesized and thoroughly characterized by UV-Vis. spectroscopy, FT-IR, atomic absorption spectroscopy, TGA and X-ray photoelectron spectroscopy techniques. The polypyrrole (PPy) functionalization reaction is monitored online using UV-Vis. spectroscopy and the kinetics of the reaction is derived for the virgin PPy formation and phthalocyanine incorporated PPy (PPy-FePcTSA). The catalytic effect of the phthalocyanine species over pyrrole monomer is evidenced from the rate of the reaction. The thermal stability of the material is improved for the modified PPy as compared to virgin PPy. The electrical conductivity of the PPy-FePcTSA materials is dependent on the concentration of the incorporated phthalocyanine. © 2011 by Nova Science Publishers, Inc. All rights reserved.