A study of the diffusion of paraffins in saturated carbon-chain polymers

Gromov, V.K.; Chalykh, A.Ye.; Vasenin, R.M.; Voyutskii, S.S.

doi:10.1016/0032-3950(65)90008-0

Cited by 5 publications

(3 citation statements)

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“…Here we will use the following approximation for x satisfying a 2 x 2 < 1 exp ( -a 2 x 2 -bx 3 -cx 4 ) ={exp ( -a 2 x 2 )){exp ( -bx 3 whereas in the present theory they (W, !, and w) are for a segment. When the segment density of a polymer coil is assumed to be Gaussian, we obtain he from eq A-6 as Substituting eq A-ll and A-12 into eq 50, we can derive a=2 (A-13)…”

Section: Approximation Of Eq 23mentioning

confidence: 99%

“…Langhammer and Nestler' measured the interfacial tension of demixed polymer solutions of polymer-polymer-solvent systems, and found very low values of interfacial tension, in the range of 10-4 -10-2 dynjcm. Morozova and Krotova, 2 Gromav and Chalykh, 3 Voyutskii, Kamenskii, and Fodiman, 4 Letz, et a!., 5 measured the thickness of the interfacial layer of polymer-polymer systems with phasecontrast microscopes or electronmicroscopes, and found very large values of the interface thickness, in the range of 10 2 -10 5 nm depending on the combination of polymers. It is not clear, however, whether the diffused interfaces measured were truly equilibrium interfaces or not.…”

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confidence: 99%

“…with the same composition as in the two homogeneous phases of the real system, and Fo is the free energy of the pure components before mixing. F' -F0 is expressed by F' -F0 =Nd,u1(e)-p 1°)+N2{p 2(e)-p2°) ( 3) where ,Ui(e) is the chemical potential of species i in phase equilibrium, and f!i 0 is that of a pure component i.…”

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Theory of Liquid—Liquid Interface of Polymer Systems

Nose

1976

Polym J

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A theory for the interfacial tension and interface thickness of demixed polymer mixtures and polymer solutions is presented on the basis of the theory of Cahn and Hilliard, taking into account the change in the dimension of polymer coil at the interface. The following results are obtained from the theory: (I) Near critical temperature Tc in a polymer mixture with the same chain length m (a symmetrical system), interfaical tension a increases with m in the t power of m, whereas in a polymer solution, a decreases with m in the-! power, compared at the same reduced temperature TITc. On the other hand, the thickness of the interface near Tc increases with increasing m, proportional to the unperturbed chain dimension, i.e., to ml/2, in a symmetrical polymer system, and to the t power in a polymer solution.(2) In high polymer systems, a first order transition from a diffuse interface to a sharp interface is predicted. The transition temperature reduced by Tc increase with increasing m. The thickness of the interface at a low temperature does not greatly depend on m and is of the order of a segment length.KEY WORDS S-So= -kA dz{c,ln (c,m,an)+c2ln (c2m2w2)) instead' of eq 12. The two expressions, however, are easily proved to be equivalent to each other in the present theory, using eq 25 and neglecting the higher (more than second) order derivatives.Polymer

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Section: Approximation Of Eq 23mentioning

confidence: 99%

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confidence: 99%

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Theory of Liquid—Liquid Interface of Polymer Systems

Nose

1976

Polym J

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Diffusion in concentrated polystyrene solutions

Paul

Mavichak

Kemp

1971

J of Applied Polymer Sci

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SynopsisThe wedge interferometer technique was used to measure the diffusion coefficients for concentrated solutions of polystyrene. A wide range of molecular weights, all monodisperse except for one, and 14 solvents were studied. Reproducibility of the data was demonstrated in the concentrated region, and good agreement with the sparse literature was observed. The experimental results are discussed and analyzed in terms of current knowledge and theories. In the concentrated region, the solvent type plays a significant role in determining the diffusion coefficient. Its effect cannot be explained simply in terms of hydrodynamics nor the molecular structure of the solvent. In cyclohexanone the diffusion coefficient was found to increase with polymer molecular weight up to 100,000 and to become independent thereafter.

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