S 66 Skripov, V. P. Spontaneous boiling up as a specific relaxation process in polymer solvent systems [Text] / V. P. Skripov, S. E. Puchinscics // Journal of Applied Polymer Science. - 1996. - V. 59, №11. - P1659-1665 Рубрики: ФИЗИКА Кл.слова (ненормированные): КИПЕНИЕ СПОНТАННОЕ -- СПОНТАННОЕ КИПЕНИЕ -- ПРОЦЕСС СПЕЦИАЛЬНЫЙ -- СПЕЦИАЛЬНЫЙ ПРОЦЕСС -- ПРОЦЕСС ОСЛАБЛЕННЫЙ -- ОСЛАБЛЕННЫЙ ПРОЦЕСС -- СИСТЕМА ПОЛИМЕРНАЯ -- ПОЛИМЕРНАЯ СИСТЕМА -- СИСТЕМА РАСТВОРЯЮЩАЯСЯ -- РАСТВОРЯЮЩАЯСЯ СИСТЕМА Аннотация: The phenomenon of spontaneous bubble nucleation in extremely supersaturated (superheated) polymer–solvent systems has been studied experimentally. Spontaneous boiling-up temperatures T* for polystyrene and poly(ethylene glycol) solutions in a number of solvents have been measured at different values of pressure p and weight fraction of polymer c by the pulse heating method. The heating rate Ṫ varied from 105 to 107 K/s. For all systems studied, the values of T* have been found to increase with increasing p and c. The T*(p, c) dependence is discussed with the use of the data on the degree of compatibility of components. The peculiarities of polymeric solutions manifest themselves in the region c → 1, as follows: (i) an abrupt increase (by 1–2 orders of magnitude) in the slope of the T*(c) dependence, and (ii) the appearance of the dependence of T* values on the heating rate. Our approach to the interpretation of this result assumes a change in the initial composition of a solution in the course of heating due to polymer decomposition. An example of the extended phase diagram of a polymer–solvent system including the kinetic surface of T*(p, c) is given |
S 89 Vshivkov, S. A. Effect of molecular dimensions of components on phase transitions in solutions of oligomeric polyethers / S. A. Vshivkov, M. Z. Faizullin // Polymer Science. Series A. - 2009. - Vol.51, №9. - С. 974-978 Рубрики: ФИЗИКА Кл.слова (ненормированные): POLYMER-SOLVENT INTERACTION -- POLYSTYRENE -- REGION Аннотация: The molecular masses and intrinsic viscosities of a series of oligomeric poly(propylene glycols) have been studied by light scattering, analysis of chain ends, viscometry, and the cloud-point method. Phase diagrams are plotted and the Flory-Huggins thermodynamic interaction parameters and the second virial coefficients are calculated for oligomeric poly(propylene glycol)-n-alkane systems. The effects of the molecular dimensions of components on their mutual solubility and positions of boundary curves are determined. UCST decreases with an increase in the size of poly(propylene glycol) macromolecules and increases with an increase in the size of n-alkane mol |
S 66 Skripov, V. P. Spontaneous boiling up as a specific relaxation process in polymer solvent systems [Text] / V. P. Skripov, S. E. Puchinscics // Journal of Applied Polymer Science. - 1996. - V. 59, №11. - P1659-1665 Рубрики: ФИЗИКА Кл.слова (ненормированные): КИПЕНИЕ СПОНТАННОЕ -- СПОНТАННОЕ КИПЕНИЕ -- ПРОЦЕСС СПЕЦИАЛЬНЫЙ -- СПЕЦИАЛЬНЫЙ ПРОЦЕСС -- ПРОЦЕСС ОСЛАБЛЕННЫЙ -- ОСЛАБЛЕННЫЙ ПРОЦЕСС -- СИСТЕМА ПОЛИМЕРНАЯ -- ПОЛИМЕРНАЯ СИСТЕМА -- СИСТЕМА РАСТВОРЯЮЩАЯСЯ -- РАСТВОРЯЮЩАЯСЯ СИСТЕМА Аннотация: The phenomenon of spontaneous bubble nucleation in extremely supersaturated (superheated) polymer–solvent systems has been studied experimentally. Spontaneous boiling-up temperatures T* for polystyrene and poly(ethylene glycol) solutions in a number of solvents have been measured at different values of pressure p and weight fraction of polymer c by the pulse heating method. The heating rate Ṫ varied from 105 to 107 K/s. For all systems studied, the values of T* have been found to increase with increasing p and c. The T*(p, c) dependence is discussed with the use of the data on the degree of compatibility of components. The peculiarities of polymeric solutions manifest themselves in the region c → 1, as follows: (i) an abrupt increase (by 1–2 orders of magnitude) in the slope of the T*(c) dependence, and (ii) the appearance of the dependence of T* values on the heating rate. Our approach to the interpretation of this result assumes a change in the initial composition of a solution in the course of heating due to polymer decomposition. An example of the extended phase diagram of a polymer–solvent system including the kinetic surface of T*(p, c) is given |
S 89 Vshivkov, S. A. Effect of molecular dimensions of components on phase transitions in solutions of oligomeric polyethers / S. A. Vshivkov, M. Z. Faizullin // Polymer Science. Series A. - 2009. - Vol.51, №9. - С. 974-978 Рубрики: ФИЗИКА Кл.слова (ненормированные): POLYMER-SOLVENT INTERACTION -- POLYSTYRENE -- REGION Аннотация: The molecular masses and intrinsic viscosities of a series of oligomeric poly(propylene glycols) have been studied by light scattering, analysis of chain ends, viscometry, and the cloud-point method. Phase diagrams are plotted and the Flory-Huggins thermodynamic interaction parameters and the second virial coefficients are calculated for oligomeric poly(propylene glycol)-n-alkane systems. The effects of the molecular dimensions of components on their mutual solubility and positions of boundary curves are determined. UCST decreases with an increase in the size of poly(propylene glycol) macromolecules and increases with an increase in the size of n-alkane mol |