Search for: second-virial-coefficient
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    Second virial coefficients of Exp-6 chains: A Monte Carlo simulation

    , Article Chemical Physics ; Volume 397, Issue 1 , March , 2012 , Pages 26-33 ; 03010104 (ISSN) Mohammadi, A ; Ramazani Saadatabadi, A ; Khanpour, M ; Sharif University of Technology
    The second virial coefficients of Exp-6 chains are calculated using the Monte Carlo method. The results are presented as the scaled second virial coefficient B 2/(m 2σ 3) for various chain lengths m and repulsive-wall steepness parameters α at different scaled temperatures T *. The scaled coefficient reduces and converges to a constant value as m → ∞. Interestingly, the scaled coefficient scales as B 2/(m 2σ 3) ∝ -α -1, where the dependence reduces for larger m. The gyration radius increases with α, and in good solvent regime, scales like a self-avoiding chain when m → ∞. The interaction energy between two chains depends on m, T *, and α. With increasing m, the interaction becomes less... 

    Modification of a new potential model used for calculation of the second virial coefficient and zero density transport properties

    , Article Molecular Physics ; Volume 104, Issue 20-21 , 2006 , Pages 3269-3280 ; 00268976 (ISSN) Parsafar, G. A ; Shokouhi, M ; Sharif University of Technology
    A new hard-core potential model was recently used to calculate thermodynamic properties of some model fluids, including equilibrium properties, such as compressibility factor and internal energy. A Lennard-Jones (LJ) like potential has been used to modify the repulsive part of the potential. The modified potential contains five parameters, namely, R, and HS. The parameter is the tail of the attractive branch whose value changes from zero to one. In this work, we have chosen = 1 to make the potential continuous at separation r = R, where the parameter R is the well width. R lies in the range 1.2 to 2.5, and R = 1.3 was found to be the best value for all real gases studied. The parameter is... 

    Computation of some thermodynamic properties of nitrogen using a new intermolecular potential from molecular dynamics simulation

    , Article Chemical Physics ; Volume 358, Issue 3 , 2009 , Pages 185-195 ; 03010104 (ISSN) Kafshdar Goharshadi, E ; Abbaspour, M ; Namayandeh Jorabchi, M ; Nahali, M ; Sharif University of Technology
    A new pair-potential energy function of nitrogen has been determined via the inversion of reduced viscosity collision integrals and fitted to obtain an analytical potential form. The pair-potential reproduces the second virial coefficient, viscosity, thermal conductivity, self-diffusion coefficient, and thermal diffusion factor of nitrogen in a good accordance with experimental data over wide ranges of temperatures and densities. We have also performed the molecular dynamics simulation to obtain pressure, internal energy, heat capacity at constant volume, and self-diffusion coefficient of nitrogen at different temperatures and densities using our calculated pair-potential and some other... 

    High molecular weight polyacrylamide nanoparticles prepared by inverse emulsion polymerization: reaction conditions-properties relationships

    , Article Colloid and Polymer Science ; Volume 294, Issue 3 , 2016 , Pages 513-525 ; 0303402X (ISSN) Tamsilian, Y ; Ramazani S. A ; Shaban, M ; Ayatollahi, S ; Tomovska, R ; Sharif University of Technology
    Springer Verlag  2016
    High molecular weight polyacrylamide (PAM) nanoparticle dispersions are products with wide application possibilities, the most important of which is in petroleum industry such as drilling fluid and flooding agent in enhanced oil recovery. For that aim, it is necessary to achieve complete control of the final dispersion and polymer properties during the synthesis step. In this work, PAMs were synthesized by inverse emulsion polymerization of aqueous acrylamide solution in cyclohexane in the presence of emulsifier mixture of Span 20 and Span 80. We present a comprehensive study of the effects of variation of all important reaction conditions (agitation rate, reaction time and temperature,...