On the Second Osmotic Virial Coefficient of Athermal Polymer Solutions

ZUSAMMENFASSUNG:Streulichtmessungen ergeben, daD Polystyrollosungen in Tetrahydrofuran stark exothermisch sind; der 2. Virialkoeffizient des osmotischen Druckes A2 wird iiberwiegend durch den Enthalpieterm A~, H bestimmt. Der Expansionskoeffizient gehorcht der (a5 -a3)-Beziehung mit der Konstante von STOCKBUYER und die h(E)-Funktion der Gleichung von CASASSA. Die Viskosititszahl [q] wird durch die Gleichung von KURATA und YAMAKAWA erfaBt. Mit den drei Parametern p/M$ KO = f i / M und b/MA (b = hydrodynamischer Durchmesser) lassen sich A2, a, [q] und der Treheitsradius f iiber einen groDen Molekulargewichtsbereich in guter Ubereinstimmung mit den MeDwerten berechnen (vgl. Abb. 3). SUMMARY:Light scattering measurements of solutions of polystyrene in tetrahydrofuran show a strongly exothermal behaviour. The major part of the second virial coefficient A2 is the enthalpie term A23. The expansion coefficient a follows the relation of FLORY, as modified by STOCEMAYER a5 -a3 = 134 z/105 and the h(l)-function complies with the equation of

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“…2 sind die MeBwerte nach GI. (12) aufgetragen. Auf der Ordinate ist der K;"-Wert aus den fruheren Messungen eingezeichnet.…”

Section: Knauelexpansion Und H(3) -Funktionunclassified

Thermodynamisches verhalten, expansionskoeffizient und viskositätszahl von polystyrol in tetrahydrofuran

Schulz

Baumann

1968

Makromol. Chem.

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“…'~~'* In addition to satisfying eq. (18), the coordinates of the maximum of the spinodal must also conform to the relation obtained by differentiating the left-hand side of eqs (18). with respect to w and equating to zero.…”

mentioning

confidence: 92%

Thermodynamic parameters of polymer‐solvent systems from light‐scattering measurements below the theta temperature

Scholte

1971

J. Polym. Sci. A‐2 Polym. Phys.

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As is well known, the chemical potentials of polymer and solvent in solution and, hence, the Flory‐Huggins interaction parameter χ can be determined from scattered light intensities from dilute and concentrated solutions of the polymer in the solvent concerned. Preferably, measurements should be performed at temperatures as low as possible, provided the temperature exceeds the cloudpoint for the concentration used. It is shown that the lower the temperature and, consequently the higher the scattered light intensity, the better is the accuracy of the parameters obtained. At each temperature the scattered light intensity shows a maximum at some concentration. Below the theta temperature the ratio of scattered light intensity and concentrations also shows a maximum at some concentration. The values and the concentrations of these maxima for various temperatures enable the maximum of the spinodal to be determined. The spinodal itself can be determined by an extrapolation procedure of the reciprocal scattered light intensities. Measurements have been performed with three narrow‐distribution polystyrene samples in cyclohexane. On the basis of the results, χ, and its dependence on concentration, temperature, and molecular weight can be determined to high accuracy.

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“…Analysis (Schulz et al, 1960(Schulz et al, , 1963(Schulz et al, , 1966Lechner and Schulz, 1973) shows that no mean field theory explains the experimental data; however, near the 0 point, the best results are obviously given by Orofino-Flory's (1957) theory and, in the case of good (athermal) 278 3.1. Binary systems solvents, Casassa's (1959Casassa's ( , 1976Casassa's ( , 1977) (see also : Casassa and Markovitz, 1958) (Equation 136), which leads to an increase in the molecular coil size in dilute solutions (see Equations 157,113,153,115).…”

Section: (154)mentioning

confidence: 99%

Thermodynamics of Systems Containing Flexible-Chain Polymers

Klenin¹,

Frenkelʹ²

1999

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On the Second Osmotic Virial Coefficient of Athermal Polymer Solutions

Cited by 48 publications

References 10 publications

Thermodynamisches verhalten, expansionskoeffizient und viskositätszahl von polystyrol in tetrahydrofuran

Thermodynamisches verhalten, expansionskoeffizient und viskositätszahl von polystyrol in tetrahydrofuran

Thermodynamic parameters of polymer‐solvent systems from light‐scattering measurements below the theta temperature

Thermodynamics of Systems Containing Flexible-Chain Polymers

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