Organochlorine Pesticides,PBBs, And Mercury in Round Whitefish Fillets from Saginaw Bay,Lake Huron, 1977–1978

Successful development of a commercial, small-mesh trap net fishery for round whitefish (Prosopium cylindraceum) in Saginaw Bay, Lake Huron, prompted analysis of round whitefish fillets for selected contaminants [dieldrin, dichlorodiphenyl trichloroethane and metabolites (DDT), polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), chlordane, methyl mercury, and total mercury] to determine the fish's suitability for human consumption. Concentrations of all contaminants measured in 1977–1978 were below U. S. Food and Drug Administration action guidelines for fish; PBBs were below detection limits (0.001 mg/kg) for all fillets analyzed. Only PCBs and total DDT residues displayed a strong direct relationship with fish length. Fillets from males consistently exhibited higher mean concentrations of contaminants than did females. No changes in contaminant levels with season were observed.     

Simplified Model for Oxygen Transport With Reaction in a Polymer‐Electrolyte Fuel Cell

A simplified mathematical model for an ion‐exchange membrane attached to a gas‐fed porous electrode is developed to simulate the oxygen electrode of a solid‐polymer‐electrolyte fuel cell. In particular, the present model is derived from an earlier rigorous one of Bernardi and Verbrugge(1991) by neglecting the Peclet number for the transport of dissolved oxygen within the catalyst. The advantage of this simpler model is that it can be solved analytically, eliminating the need for numerical simulation. Longitudinal profiles for the dissolved oxygen concentration and catalyst current density calculated from the present model are in good agreement with results from the earlier rigorous model.     

Electrochemical copolymerization and characterization of aniline and isoprene in aqueous p‐toluene sulfonic acid solution

Uniform and adherent copolymer coating of poly(aniline‐co‐isoprene) was successfully formed on low‐carbon‐steel electrodes by potentiostatic electropolymerization. Electropolymerization was performed by using aqueous p‐toluene sulfonic acid solution as electrolyte. Applied potential and feed ratios of monomers (aniline and isoprene) were systematically varied and the reactions were done under aqueous conditions. The copolymer coatings were characterized by infrared spectroscopy and the formation of copolymer was confirmed by the presence of aliphatic secondary amine, aromatic secondary amine, and aliphatic CH stretch groups. The electronic structure of the copolymers was further investigated by using UV/Vis absorption spectroscopy. The electrochemistry of the formation of copolymers was studied by using cyclic voltammetry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 184–192, 2002; DOI 10.1002/app.10298     

Mechanism and kinetics of curing of diglycidyl ether of bisphenol a (DGEBA) resin by chitosan

Crosslinking behavior of Diglycidyl Ether of Bisphenol A (DGEBA) resins cured by chitosan was isothermally studied by Fourier Transform Infrared (FTIR) Spectroscopy for various molar ratios of chitosan at different temperatures. Results indicated that oxirane undergoes nucleophilic attack by the primary amine groups in chitosan to form crosslinked structure. Epoxy fractional conversion (α ) was calculated by following the change in area of oxirane peak at 914 cm^?1. Value of α and reaction rate (dα /dt ) increased with increase in curing temperature and chitosan concentration. The maximum epoxy fractional conversion of 70% was obtained for 1:4 molar ratio (Epoxy:Chitosan) at 200°C. A four parameter kinetic model with two rate constants was employed to simulate the experimental data. Overall reaction order and activation energy for all compositions were in the range of 2.5–3 and 25–50 kJ mol^?1, respectively. Results indicated that cure reaction is autocatalytic and does not follow simple n th order cure kinetics. Thermogravimetric analysis (TGA) performed on chitosan cured DGEBA films and compared against neat epoxy and neat chitosan films. Results showed that the degradation of chitosan crosslinked epoxy network occurred in the temperature range of 450–550°C. POLYM. ENG. SCI., 57:865–874, 2017. © 2016 Society of Plastics Engineers     

Effect of process parameters on the electropolymerization potential and rate of formation of polypyrrole on stainless steel

Polypyrrole coatings were formed on stainless steel working electrodes in aqueous oxalic acid solution. The rate of formation of polypyrrole coatings on stainless steel increased proportionately with the current density but increased slightly with increased pyrrole concentration. Increasing oxalic acid concentration also had no significant change in the polymerization rate. The electropolymerization potential of pyrrole decreased significantly from 1.5 to 0.8 V versus SCE when the working electrode was polished. The polymerization potential, E_p, of pyrrole, increased however, with increased current density and decreased exponentially with the initial monomer and electrolyte concentration, respectively. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2433–2440, 1997     

Morphology,mechanical and thermal properties of nano-structured full IPNs based on polyisoprene and PMMA

Morphology, mechanical properties, thermal stability and gas transport behaviour of interpenetrating polymer networks (IPNs) based on PI/PMMA have been investigated using various techniques. Crosslinking level of both phases and concentration of PMMA were found to have noticeable effects on the compatibility of immiscible components during IPN formation. Effect of crosslinking was studied by preparing IPNs with varying amount of crosslinker concentration in each phase. Crosslinking of both phases facilitated deeper interpenetrations between both networks, and certain degree of compatibility is attained during IPN formation. Nanometre-sized domains were observed for highly crosslinked IPN. Lower concentration of PMMA was found to favour phase mixing more effectively than others. DSC curve of 65/35 IPN showed a broad transition arising from the α and β-relaxations of PMMA due to the higher flexibility attained by mixing with the highly mobile PI chains. The mechanical properties of the IPNs were correlated to the morphology of the system and 50/50 composition showed maximum mechanical properties among the studied compositions. Mode of mechanical failure, thermal stability and gas transport behaviour were also analysed. IPNs having nanometre-sized domains showed least gas permeability among the studied samples.     

Alkali-promoted hydrothermal gasification of biomass food processing waste: A parametric study

A parametric study of alkali-promoted hydrogen gas production from by-products from food-based biomass, such as glucose, molasses and rice bran, under hydrothermal conditions has been carried out. Partial oxidation of the biomass samples was aided by the addition of hydrogen peroxide and experiments were carried out in the presence of sodium hydroxide. The effects of reaction temperature, reaction time and feed concentration on the conversion of glucose, molasses and rice bran to gaseous products under hydrothermal conditions were investigated. The reaction time and reaction temperature were investigated in the range of 0–120 min and 330–390 °C, respectively. The results confirmed the positive influence of NaOH in the production of hydrogen gas via the water–gas shift reaction. In the presence of the alkali, no tar/oil and char were observed. The hydrogen gas yield increased when the reaction temperature and reaction time increased. It was observed that higher reaction temperature led to an increase in the amount of methane gas produced. With increasing feed concentration, the yields of other gases such as CO, CO₂, CH₄ and C₂–C₄ increased, while hydrogen gas production decreased for all the biomass samples. The generation of gaseous products from the molasses and rice bran showed a similar trend to that of glucose, under identical test conditions.     

Effect of clay on the corrosion inhibition and dynamic mechanical properties of epoxy ester–polyurea–polysiloxane hybrid coatings

The corrosion resistance of polymeric coatings containing epoxy ester, polyurea, and polymethylhydrosiloxane was significantly improved by the addition of cloisite 15A organoclay. The weight percent of organoclay was varied from 0.5 to 10%. The presence of organoclay in the coatings was confirmed using the Fourier transformed infrared spectroscopy. The effect of organoclay on the surface energy of the coatings was analyzed by measuring contact angle with a video contact angle analyzer and using water and iodomethane as the probing liquids. The surface energy of the coatings increased with increasing organoclay concentration. The corrosion resistant properties were measured by direct current polarization technique. The addition of organoclay enhanced the corrosion resistance of the coatings, and the best corrosion resistance was shown by coating containing 1% organoclay. The dynamic mechanical property of the coatings was determined using the dynamic mechanical spectrometer. The glass transition temperature of the films decreased significantly with the addition of organoclay up to 1% after which it increased with additional increase in the wt% of organoclay. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Natural gas—International: China to supply huge natural gas growth

As the projected fastest-growing fossil fuel through 2030, natural gas is viewed as the “bridge” source to a more sustainable energy future. Combusted gas emits 30 percent less carbon dioxide (CO₂) than oil and 45 percent less than coal and has lower levels of nitrogen oxides, sulfur dioxide, and particulate matter.     

Carbon fiber-polyaniline composites: Kinetics of electrodeposition of polyaniline onto carbon fibers by cyclic voltammetry

Homogeneous and uniform coatings of polyaniline were successfully deposited on carbon fibers by an aqueous electrodeposition technique using p-toluene sulfonic acid as the electrolyte. Electrochemical deposition of aniline was carried out by cyclic voltammetry in the potential range of ?0.2 V to 1.0 V versus saturated calomel electrode (SCE). The electrochemical deposition parameters such as the number of cycles, scan rate (SR), initial monomer ([M]), and electrolyte concentration ([E]) were systematically varied. The amount of composite coatings on carbon fibers was dependent on the electrochemical deposition parameters. From a weight gain analysis, the rate of the reactions (R p ) was calculated. As the aniline concentration was increased up to 0.35 M and electrolyte concentration up to 0.5 M, the deposition rate also increased, whereas an increase in scan rate decreased the deposition rate. Kinetic analysis showed that the rate equation for the p-toluene sulfonic acid system is R p ∝SR ?1.25 [M] 0.73 [E] 0.95 . IR spectra also showed an increase in the deposition of polyaniline coatings on carbon fibers with a decrease in the scan rate and an increase in both monomer and electrolyte concentration. The ratio of two oxidation states of polyaniline obtained during electrodeposition, namely emeraldine and pernigraniline, can be varied by changing the electrochemical deposition parameters.