Phase-separation studies

Wood and Hill consider that the role of fluoride in these glasses is uncertain. Phase-separation studies suggest that the structure of the glass might relate to the crystalline species formed, in which case a microcrystallite glass model is appropriate. But other evidence cited above on the structure-breaking role of fluoride is compatible with a random network model. 

Thermodynamic parameters are calculated from intrinsic viscosities and their temperature coelBcients. The values are significantly lower than those obtained by other methods, such as osmotic method (cf. Exercise 3.10) and phase separation studies (see Problem 3.16)... 

Thermodynamic parameters are derived from phase separation studies. 

One indication of the effects of solvency comes from the phase separation studies of silica particles reported by Pathmamanoharan et al. (1981). They found that in a good solvent V2 for polystyrene was decreased by a factor of 3 when the solvent was changed from cyclohexane at the 0-point to the good solvent toluene. This is suggestive that depletion effects may be significantly greater in good solvents than in 0-solvents for some systems. 

Zielinski, J., Vratsanos, M.. Laurer, J., and Spontak. R.. Phase separation studies of heat-cured ATU-flexibilized epoxies. Polymer, 37, 1, 75 84 (1996). 

Zielinski, JM, Vratsanos, MS, Laurer, HJ, Spontak, RJ. 1996. Phase-separated studies of heat-cured flexibUized... 

The theta temperature of a polymCT-solvent systen can be measured from phase separation studies. The value of at the critical concentration is related to the chain length of the polymer by Equation 8.39, and substitution in Equation 8.45 leads to... 

The expression provides a criterion to predict whether or not the mixed solvent is expected to be a cosolvent of the polymer. When T, is a UCST (as is the case in these phase separation studies), -dx /dT > 0 and (dTc/dx)o has the same sign as the numerator of the equation. Choosing solvent 1 such that T 2 < T, then (dTc/dx)o < 0 guarantees that the system will be a cosolvent one. Since %23 - Zi3 > 0, at T i, the numerator in the equation [5.4.1] is negative (cosolvent system) if the unfavorable interaction between the two liquids is large enough to compensate for their different affinity towards the polymer. The equation proposed gives a more detailed criterion for cosolvency than the simple criterion of G > 0. The information needed to predict (dTydx)o from equation [5.4.1] includes the binary interaction parameters of the polymer in each one of the two solvents as a function of temperature, and Xi2(G ) for the mixed solvent too. Table 5.4.1 summarizes results reported by Horta et al. for some cosolvents of polymethylmethacrylate (PMMA). ... 

The present review begins with a brief description of the basic principles of luminescence [1-3], after which it deals with the fluorescence studies of polymers in solution and energy transfer in polymeric systems. Spectral and time dependent studies of polymers in the gel state are discussed later, with an emphasis on phase transition and phase separation studies. 

The sodium and ammonium salts of PVSA are soluble in water but insoluble in organic solvents (6). The calcium salt is insoluble. Potentiometric titration studies indicate that PVSA is a strong acid that ionizes completely in water. Ion binding selectivity with alkali metals has been observed in viscosity and phase separation studies. Mark-Houwink-Sakurada (MHS) parameters ofK = 2.22 and a = 0.65 have been obtained for sodium PVSA in 0.5 M NaCl at 25°C. 

Pieters R, MUtner HE, Van Assche G, Van Mele B (2006) Kinetics of temperature-induced and reaction-induced phase separation studied by modulated temperature DSC. Macromol Symp 233 36-41... 

Microthermal analysis is being developed as a tool for carrying out studies in a nnmber of areas including morphology, topography, glass transitions, depth probing, and phase separation studies. 

Phase separation studies Song and co-workers [348] used microthermal analysis to study the phase separation process in a 50 50 (by weight) PS/polyvinylmethylether blend and nitrile rubber. Microthermal analysis will image the composition in the near-surface region or surface region of multi-component materials if the resolution is high enough. 

Phase separation studies in RIM polyurethanes catalyst and hard segment crystallinity effects. Polymer, 26, 1145-1154. 

Smits, A. L. M., Wubbenhorst, M., Kruiskamp, P. H., Van Soesf J. J. G., Vliegenthart, J. F. G., and Van Tumhout, J. (2001). Structure evolution in amylopectin/ethylene glycol mixtures by H-bond formation and phase separation studied with dielectric relaxation spectroscopy. J. Phys. Chem. B 105, 5630 5636. 

TER Terao, K., Okmnoto, M., Nakamura, Y., Norisuye, T., and Teramoto, A., Lightscattering and phase separation studies on cyclohexane solutions of four-arm star polystyrene, MrcroTwo/ecw/es, 31, 6885, 1998. 

Morphology and Phase Separation Studies in PER/PBNCO and PER/HTPB Biends... 

The expression provides a criterion to predict whether or not the mixed solvent is expected to be a cosolvent of the polymer. When T, is a UCST (as is the case in these phase separation studies), -d /dT > 0 and (dTc/dx)o has the same sign as the numerator of the equation. Choosing solvent 1 such that Tc2 Tci, then (dT, /dx)o < 0 guarantees that the system will be a cosolvent one. Since %23 Xis the numerator in the equation [5.4.1] is... 

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