Segregation, degree

In ideal pipe reactor, the liquid elements do not exchange their contents with their surroundings (in axial direction). This is described by the term complete segregation (degree of segregation of 1) and the liquid is named macro-liquid. In a stirred tank, which is ideally back-mixed on a molecular level, micro-liquid exists with a zero degree of segregation. 

Gonzalez I, Paulis M, de la Cal JC, Asua JM. Miniemulsion polymerization effect of the segregation degree on polymer architecture. Macromol React Eng 2007 1 635-642. 

The comparatively low values of segregation degree show that a great amount of the system mass is preserved in the unseparated state and is distributed in two phases. Thus, segregation degree is a measure of incompleteness of the phase separation or deviation of the system from the state of true thermodynamic equilibrium. 

The comparison of the data on the segregation degree and on free energy of pol5Tner-filler interaction shows that segregation diminishes both in the presence of fillers having thermodynamic affinity to polymers and for fillers having no affinity. Two mechanisms of compatibilization are supposed to operate here ... 

Table 7.4 Modulus, E, glass transition temperature, Tg, and segregation degree, a, of filled IPNs based on polyurethane, PU, and poly (ester acrylate), PEA...

Rosovitsky V F and Lipatov Y S (1985) To determination of segregation degree in two phase polymer systems on parameters of relaxation maxima. Reports Acad Sci USSR 283 910-913 (in Russian). 

All the ideas connected with the nonequilibrium multiphase structure of IPNs are in good agreement with a comparatively low segregation degree in IPNs (see Chap. 4, this volume). In such a way the whole structure of IPNs may be presented as a mesophase matrix with embedded microphase regions, which represent two evolved phases. Such a structural model coincides with the spinodal mechanism of decomposition. 

To evaluate the heterogeneity of the phase-separated IPN and the degree of phase separation (segregation degree) various approaches can be used. The most fundamental one is based on SAXS in the form proposed by Bonart and... 

It should be noted from the very beginning that segregation degree is a relative value, which characterizes the hypothetical system where a is the fraction of fully separated material whereas (1 - a) remains in the unseparated state. It is evident that the real situation does not correspond to such a simple picture. In spite of this, the value of segregation degree is a quantitative value which allows one to probe the most important properties of phase-separated IPNs. 

Unfortunately, there was no attempt to compare the quantitative structure parameters (except segregation degree) with the viscoelastic properties of IPNs. It is more difficult to compare qualitative electron microscopy data with physical properties of the systems. 

In principle, similar results were obtained in all subsequent investigations done for various systems [189-191]. As a rule, the temperature transition for the elastomeric component shifts to higher temperatures, whereas the temperature transition for the more rigid component shifts to lower temperatures. Now we can say that these shifts are determined by the formation of two phases with different compositions (initially these shifts were ascribed to the changing compatibility of two components). Eor semi-IPNs based on PU and PHEMA [191], the segregation degree varies in the limits 0.22-0.35,... 

MM OIG % of EO Segregation degree Domain dimension, nm Tg OIG region, K TgEO region, K... 

Determining the Segregation Degree from Parameters of Relaxation Maxima... 

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