本研究以非平衡態分子動力學模擬具有支鏈結構的短鏈烷類分
子於穩態剪切流場中的流變性質與行為，三種流體系統分別為短鏈聚
丙烯(C24H50)、星狀烷類(C16H34)及星狀與直鏈烷類(C16H34)的混合流
體，三者皆出現非牛頓流體的shear dilatancy 及shear thinning 現象。
比較相同主鏈長度的短鏈聚丙烯與文獻中的直鏈烷類n-hexadecane，
前者鬆弛時間較短且shear thinning 程度較低。兩種分子的鍵角彎曲
勢能於高剪切率區域變化相異：短鏈聚丙烯下降而n-hexadecane 增
加，推論支鏈結構會影響高剪切率下的鍵角分布，此為支鏈與直鏈分
子流變行為差異的主要原因；星狀分子的鍵角彎曲勢能亦為下降趨
勢。由扭轉二面角分布觀察到不同溫度系統中，剪切流場作用對星狀
分子鍵扭轉運動的影響程度不同。針對星狀分子本身的兩種結構，分
支-CH2-(CH2)3-CH3 與中心粒子CH，分析熱力學狀態效應下的結構平
均勢能，發現溫度為影響分支結構鍵結勢能的主因；而溫度、壓力與
密度皆會影響中心粒子的鍵拉伸與鍵角彎曲勢能，但中心粒子的鍵扭
轉勢能只受溫度影響。由星狀分子兩種結構的扭轉二面角分布，分析
剪切流場中分子鏈的柔軟度。另外於星狀與直鏈烷類的混合系統中，
發現不同組成比例的流體黏度反轉現象。

[1] D. M. Heyes, "Shear thinning and thickening of the Lennard–Jones liquid - A molecular dynamics study," Journal of the Chemical Society, Faraday Transactions 2, vol. 82, 1365, 1986.
[2] D. J. Evans and G. P. Morriss, "Shear thickening and turbulence in simple fluids," Physical Review Letters, vol. 56, 2172, 1986.
[3] S. Balasubramanian, C. J. Mundy, and M. L. Klein, "Shear viscosity of polar fluids: Molecular dynamics calculations of water," Journal of Chemical Physics, vol. 105, 11190, 1996.
[4] A. Jabbarzadeh, J. D. Atkinson, and R. I. Tanner, "Nanorheology of molecularly thin films of n-hexadecane in Couette shear flow by molecular dynamics simulation," Journal of Non-Newtonian Fluid Mechanics, vol. 77, 53, 1998.
[5] A. Jabbarzadeh, J. D. Atkinson, and R. I. Tanner, "Wall slip in the molecular dynamics simulation of thin films of hexadecane," Journal of Chemical Physics, vol. 110, 2612, 1999.
[6] A. Jabbarzadeh, J. D. Atkinson, and R. I. Tanner, "Effect of the wall roughness on slip and rheological properties of hexadecane in molecular dynamics simulation of Couette shear flow between two sinusoidal walls," Physical Review E, vol. 61, 690, 2000.
[7] A. Jabbarzadeh, J. D. Atkinson, and R. I. Tanner, "The effect of branching on slip and rheological properties of lubricants in molecular dynamics simulation of Couette shear flow," Tribology International, vol. 35, 35, 2002.
[8] R. L. Rowley and J. F. Ely, "Non-equilibrium molecular dynamics simulations of structured molecules," Molecular Physics, vol. 72, 831, 1991.
[9] J. Petravic and J. Delhommelle, "Hydrogen bonding in ethanol under shear," Journal of Chemical Physics, vol. 122, 234509, 2005.
[10] D. R. Wheeler and R. L. Rowley, "Shear viscosity of polar liquid mixtures via non-equilibrium molecular dynamics: water, methanol, and acetone," Molecular Physics, vol. 94, 555, 1998.
[11] J. D. Moore, et al., "A molecular dynamics study of a short-chain polyethylene melt. I. Steady-state shear," Journal of Non-Newtonian Fluid Mechanics, vol. 93, 83, 2000.
[12] J. D. Moore, et al., "A molecular dynamics study of a short-chain polyethylene melt. II. Transient response upon onset of shear," Journal of Non-Newtonian Fluid Mechanics, vol. 93, 101, 2000.
[13] A. Jabbarzadeh, J. D. Atkinson, and R. I. Tanner, "Effect of molecular shape on rheological properties in molecular dynamics simulation of star, H, comb, and linear polymer melts," Macromolecules, vol. 36, 5020, 2003.
[14] J. T. Bosko, B. D. Todd, and R. J. Sadus, "Molecular simulation of dendrimers and their mixtures under shear: Comparison of isothermal-isobaric (NpT) and isothermal-isochoric (NVT) ensemble systems," Journal of Chemical Physics, vol. 123, 034905, 2005.
[15] T. C. Le, et al., "The effect of interbranch spacing on structural and rheological properties of hyperbranched polymer melts," Journal of Chemical Physics, vol. 131, 164901, 2009.
[16] L. I. Kioupis and E. J. Maginn, "Rheology, dynamics, and structure of hydrocarbon blends: a molecular dynamics study of n-hexane/n-hexadecane mixtures," Chemical Engineering Journal, vol. 74, 129, 1999.
[17] Y.-R. Jeng, C.-C. Chen, and S.-H. Shyu, "Concentration effects on lubrication rheology for polymer solution in molecularly thin film using molecular dynamics," Journal of Applied Physics, vol. 95, 8450, 2004.
[18] P. G. d. Gennes, "Reptation of a polymer chain in the presence of fixed obstacles," Journal of Chemical Physics, vol. 55, 572, 1971.
[19] M. Doi and S. F. Edwards, The Theory of Polymer Dynamics. Place Published: Oxford University Press, 1986.
[20] S. T. Milner and T. C. B. McLeish, "Parameter-free theory for stress relaxation in star polymer melts," Macromolecules, vol. 30, 2159, 1997.
[21] T. C. B. McLeish and R. G. Larson, "Molecular constitutive equations for a class of branched polymers: The pom-pom polymer," Journal of Rheology, vol. 42, 81, 1998.
[22] T. C. B. McLeish, et al., "Dynamics of entangled H-polymers: Theory, rheology, and neutron-scattering," Macromolecules, vol. 32, 6734, 1999.
[23] D. R. Daniels, et al., "Molecular rheology of comb polymer melts. 1. Linear viscoelastic response," Macromolecules, vol. 34, 7025, 2001.
[24] J. J. Vosloo, et al., "Thermal and viscoelastic structure–property relationships of model comb-like poly(n-butyl methacrylate) " Polymer, vol. 48, 205, 2007.
[25] P. Chambon, et al., "Synthesis, temperature gradient interaction chromatography, and rheology of entangled styrene comb polymers," Macromolecules, vol. 41, 5869, 2008.
[26] H.-C. Tseng, J.-S. Wu, and R.-Y. Chang, "Shear thinning and shear dilatancy of liquid n-hexadecane via equilibrium and nonequilibrium molecular dynamics simulations: Temperature, pressure, and density effects," Journal of Chemical Physics, vol. 129, 014502, 2008.
[27] H.-C. Tseng, J.-S. Wu, and R.-Y. Chang, "Molecular structural property and potential energy dependence on nonequilibrium thermodynamic state point of liquid n-hexadecane under shear," Journal of Chemical Physics, vol. 134, 044511, 2011.
[28] J. H. Irving and J. G. Kirkwood, "The statistical mechanical theory of transport processes. IV. the equations of hydrodynamics," Journal of Chemical Physics, vol. 18, 817, 1950.
[29] B. J. Alder and T. E. Wainwright, "Phase transition for a hard sphere system," Journal of Chemical Physics, vol. 27, 1208, 1957.
[30] B. J. Alder and T. E. Wainwright, "Studies in molecular dynamics. I. General method," Journal of Chemical Physics, vol. 31, 459, 1959.
[31] A. Rahman, "Correlations in the motion of atoms in liquid argon," Physical Review, vol. 136, 405, 1964.
[32] F. H. Stillinger and A. Rahman, "Improved simulation of liquid water by molecular dynamics," Journal of Chemical Physics, vol. 60, 1545, 1974.
[33] J. Koplik and J. R. Banavar, "Molecular dynamics of interface rupture," Physics of Fluids A, vol. 5, 521, 1993.
[34] D. Rigby and R. J. Roe, "Molecular dynamics simulation of polymer liquid and glass. I. Glass transition," Journal of Chemical Physics, vol. 87, 7285, 1987.
[35] D. Rigby and R. J. Roe, "Molecular dynamics simulation of polymer liquid and glass. II. Short-range order and orientation correlation," Journal of Chemical Physics, vol. 89, 5280, 1988.
[36] D. Rigby and R. J. Roe, "Molecular dynamics simulation of polymer liquid and glass. III. Chain conformation," Macromolecules, vol. 22, 2259, 1989.
[37] D. Rigby and R. J. Roe, "Molecular dynamics simulation of polymer liquid and glass. IV Free-volume distribution," Macromolecules, vol. 23, 5312, 1990.
[38] S. Fujiwara and T. Sato, "Molecular dynamics simulations of structural formation of a single polymer chain: Bond-orientational order and conformational defects," Journal of Chemical Physics, vol. 107, 613, 1997.
[39] A. Koyama, et al., "Molecular dynamics simulation of polymer crystallization from an oriented amorphous state," Physical Review E, vol. 65, 050801, 2002.
[40] J. J. Erpenbeck, "Shear viscosity of the Lemmard–Jones fluid near the triple point: Green–Kubo results," Physical Review A, vol. 38, 6255, 1988.
[41] M. P. Allen and D. J. Tildesley, Computer Simulation of Liquids. Place Published: Oxford University Press, 1989.
[42] S. T. Cui, P. T. Cummings, and H. D. Cochran, "The calculation of viscosity of liquid n-decane and n-hexadecane by the Green–Kubo method," Molecular Physics, vol. 93, 117, 1998.
[43] D. J. Evans, G. P. Morriss, and L. M. Hood, "On the number dependence of viscosity in three dimensional fluids," Molecular Physics, vol. 68, 637, 1989.
[44] A. Berker, et al., "Non-equilibrium molecular dynamics (NEMD) simulations and the rheological properties of liquid n-hexadecane," Journal of the Chemical Society-Faraday Transactions, vol. 88, 1717, 1992.
[45] B. Busic, J. Koplik, and J. R. Banavar, "Molecular dynamics simulation of liquid bridge extensional flows," Journal of Non-Newtonian Fluid Mechanics, vol. 109, 51, 2003.
[46] P. J. Daivis, M. L. Matin, and B. D. Todd, "Nonlinear shear and elongational rheology of model polymer melts by non-equilibrium molecular dynamics," Journal of Non-Newtonian Fluid Mechanics, vol. 111, 1, 2003.
[47] J. G. H. Cifre, S. Hess, and M. Kröger, "Linear viscoelastic behavior of unentangled polymer melts via non-equilibrium molecular dynamics," Macromolecular Theory and Simulations, vol. 13, 748, 2004.
[48] J. Koplik, J. R. Banavar, and J. F. Willemsen, "Molecular dynamics of poiseuile flow and moving contact lines," Physical Review Letters, vol. 60, 1282, 1988.
[49] P. A. Thompson and S. M. Troian, "A general boundary condition for liquid flow at solid surfaces," Nature, vol. 389, 360, 1997.
[50] R. Edberg, G. P. Morriss, and D. J. Evans, "Rheology of n-alkanes by nonequilibrium molecular dynamics," Journal of Chemical Physics, vol. 86, 4555, 1987.
[51] P. J. Daivis and D. J. Evans, "Computer simulation study of the comparative rheology of branched and linear alkanes," Journal of Chemical Physics, vol. 97, 616, 1992.
[52] S. T. Cui, P. T. Cummings, and H. D. Cochran, "Multiple time step nonequilibrium molecular dynamics simulation of the rheological properties of liquid n-decane," Journal of Chemical Physics, vol. 104, 255, 1996.
[53] S. T. Cui, et al., "Molecular dynamics simulations of the rheology of normal decane, hexadecane, and tetracosane," Journal of Chemical Physics, vol. 105, 1214, 1996.
[54] R. Khare, J. J. d. Pablo, and A. Yethiraj, "Rheological, thermodynamic, and structural studies of linear and branched alkanes under shear," Journal of Chemical Physics, vol. 107, 6956, 1997.
[55] J. D. Moore, et al., "Rheology of lubricant basestocks: A molecular dynamics study of C30 isomers," Journal of Chemical Physics, vol. 113, 8833, 2000.
[56] S. Bair, C. McCabe, and P. T. Cummings, "Comparison of nonequilibrium molecular dynamics with experimental measurements in the nonlinear shear-thinning regime," Physical Review Letters, vol. 88, 058302, 2002.
[57] M. Kröger, W. Loose, and S. Hess, "Rheology and structural changes of polymer melts via nonequilibrium molecular dynamics," Journal of Rheology, vol. 37, 1057, 1993.
[58] T. Aoyagi and M. Doi, "Molecular dynamics simulation of entangled polymers in shear flow," Computational and Theoretical Polymer Science, vol. 10, 317, 2000.
[59] M. Kröger and S. Hess, "Rheological evidence for a dynamical crossover in polymer melts via nonequilibrium molecular dynamics," Physical Review Letters, vol. 85, 1128, 2000.
[60] R. B. Bird, R. C. Armstrong, and O. Hassager, Fluid Mechanics, Dynamics of Polymeric Liquids, 2nd ed. vol. 1. Place Published: Wiley-Interscience, 1987.
[61] H.-C. Tseng, J.-S. Wu, and R.-Y. Chang, "Material functions of liquid n-hexadecane under steady shear via nonequilibrium molecular dynamics simulations: Temperature, pressure, and density effects," Journal of Chemical Physics, vol. 130, 084904, 2009.
[62] H.-C. Tseng, J.-S. Wu, and R.-Y. Chang, "Master curves and radial distribution functions for shear dilatancy of liquid n-hexadecane via nonequilibrium molecular dynamics simulations," Journal of Chemical Physics, vol. 130, 164515, 2009.
[63] H.-C. Tseng, J.-S. Wu, and R.-Y. Chang, "Linear viscoelasticity and thermorheological simplicity of n-hexadecane fluids under oscillatory shear via non-equilibrium molecular dynamics simulations," Physical Chemistry Chemical Physics, vol. 12, 4051, 2010.
[64] H. A. Barnes, J. F. Hutton, and K. Walters, An Introduction to Rheology. Place Published: Elsevier, 1989.
[65] J. D. Ferry, Viscoelastic Properties of Polymers, 3rd ed. Place Published: Wiley, 1980.
[66] Z. Xu, J. J. d. Pablo, and S. Kim, "Transport properties of polymer melts from nonequilibrium molecular dynamics," Journal of Chemical Physics, vol. 102, 5836, 1995.
[67] M. Lahtela, et al., "Computer simulations of branched alkanes: The effect of side chain and its position on rheological behavior," Journal of Chemical Physics, vol. 108, 2626, 1998.
[68] S. H. Lee, "The rheology of 6-propyl duodecane and 5-dibutyl nonane by non-equilibrium molecular dynamics simultions," Molecular Simulation, vol. 22, 271, 1999.
[69] S. H. Lee, "The rheology of liquid pentane isomers by non-equilibrium molecular dynamics simulations," Molecular Simulation, vol. 23, 243, 2000.
[70] L. I. Kioupis and E. J. Maginn, "Molecular simulation of poly-a-olefin synthetic lubricants: Impact of molecular architecture on performance properties," Journal of Physical Chemistry B, vol. 103, 10781, 1999.
[71] J. Castillo-Tejas, et al., "Nonequilibrium molecular dynamics of the rheological and structural properties of linear and branched molecules. Simple shear and poiseuille flows; instabilities and slip," Journal of Chemical Physics, vol. 123, 054907, 2005.
[72] P. M. Wood-Adams, "The effect of long chain branches on the shear flow behavior of polyethylene," Journal of Rheology, vol. 45, 203, 2001.
[73] J. P. Ryckaert and A. Bellemans, "Molecular dynamics of liquid n-butane near its boling point," Chemical Physics Letters, vol. 30, 123, 1975.
[74] A. W. Lees and S. F. Edwards, "The computer study of transport processes under extreme conditions," Journal of Physics Part C Solid State Physics, vol. 5, 1921, 1972.
[75] D. Macgowan and D. M. Heyes, "Large timesteps in molecular dynamics simulations," Molecular Simulation, vol. 1, 277, 1988.
[76] W. G. Hoover, et al., "Lennard–Jones triple-point bulk and shear viscosities. Green–Kubo theory, Hamiltonian mechanics, and nonequilibrium molecular dynamics Hamiltonian mechanics, and nonequilibrium molecular dynamics," Physical Review A, vol. 22, 1690, 1980.
[77] B. D. Todd and P. J. Daivis, "Homogeneous non-equilibrium molecular dynamics simulations of viscous flow: techniques and applications," Molecular Simulation, vol. 33, 189, 2007.
[78] D. J. Evans and G. Morris, Statistical Mechanics of Nonequilibrium Liquids, 2nd ed. Place Published: Cambridge University Press, 2008.
[79] P. J. Daivis and D. J. Evans, "Comparison of constant pressure and constant volume nonequilibrium simulations of sheared model decane," Journal of Chemical Physics, vol. 100, 541, 1994.
[80] C. J. Mundy, J. I. Siepmann, and M. L. Klein, "Decane under shear: A molecular dynamics study using reversible NVT-SLLOD and NPT-SLLOD algorithms," Journal of Chemical Physics, vol. 103, 10192, 1995.
[81] J. Delhommelle and D. J. Evans, "Comparison of thermostatting mechanisms in NVT and NPT simulations of decane under shear," Journal of Chemical Physics, vol. 115, 43, 2001.
[82] Y.-M. Tsai and R.-Y. Chang, "Methyl branch effects on rheological behaviours of short-chain polypropylene under steady shear studied via nonequilibrium molecular dynamics simulations," Molecular Simulation, vol. 38, 124, 2012.
[83] J. M. Kim, et al., "Rheological and entanglement characteristics of linear-chain polyethylene liquids in planar Couette and planar elongational flows," Journal of Non-Newtonian Fluid Mechanics, vol. 152, 168, 2008.
[84] C. Baig and V. G. Mavrantzas, "Tension thickening, molecular shape, and flow birefringence of an H-shaped polymer melt in steady shear and planar extension," Journal of Chemical Physics, vol. 132, 014904, 2010.
[85] J. H. R. Clarke and D. Brown, "The rheological properties of liquids composed of flexible chain molecules: A molecular dynamics computer simulation study," Journal of Chemical Physics, vol. 86, 1542, 1987.
[86] L. I. Kioupis and E. J. Maginn, "Impact of molecular architecture on the high-pressure rheology of hydrocarbon fluids," Journal of Physical Chemistry B, vol. 104, 7774, 2000.