Pulse induced critical scattering

Experimental measurements of the spinodal curve require bridging of the metastable region of the miscibility gap, i.e. traversing this region without phase separation. A nice technique developed for this purpose is the Pulse Induced Critical Scattering (PICS) [64]. 

KI2 Kiepen, F. and Borehard, W., Pressure-pulse-induced critical scattering of ohgostyrene in n-... 

KI4 Kiepen, F. and Borehard, W., Determination of binodal and spinodal points by means of the pressure pulse-induced critical scattering method, Integr. Fundam. Polym. Sci. Technol., Elsevier, London, 2, 227, 1988. 

If no experimental demixing data are available, the adjustable model parameter can be estimated using other experimental data. One option is the utilization of experimental spinodal data in Eq. (10.23). Spinodal data can be measured using temperature pulsed or pressure pulsed induced critical scattering. 

To improve the accuracy and reliability of the extrapolation procedure A HaLo anGreat Britain) (Gordon et al., 1974, 1975). The method itself was named pulse-induced critical scattering (PICS) (l)erhain et al., 1974 Gordon et al., 1974, 1975 Kennedy el al., 1975). 

Derham K., Goldsbrough J., Gordon M., (1974) Pulse-induced critical scattering (PICS) from polymer solutions, PureAppl. Chem. 38,97. 

Wells P.A., De Loos Th.W., Kleintjens L.A., (1993), Pressure Pulse Induced Critical Scattering Spinodal and binodal curves for Pst/methyl/cyclohexane, Fluid Phase Equil 83., 3. 

Pulse-induced critical scattering (126,127), although not utilized as a method for molecular weight characterization, may be a sensitive procedure for detecting small differences in molecular weight distribution. 

Recent work has also studied features of the cloud-point curve, which can sometimes show binodality, and tried to explain this theoretically." -" The technique of pulse-induced critical scattering has also been developed where a sample is very quickly quenched into the metastable part of the miscibility gap then quickly reheated. While the sample is cool, scattering measurements are made that... 

GOR Gordon, M., Irvine, P., and Kennedy, J.W., Phase diagrams and pulse-induced critical scattering, J. Polym. Sci. Polym. Symp., 61,199,1977. 

KAJ Kajiwara, K., Burchard, W., Kleintjens, L.A., and Koningsveld, R., Pulse induced critical scattering from solutions of randomly crosslinked polystyrene in cyclohexane, Po/yw. Bull., 7, 191, 1982. 

WEL Wells, P.A., Loos, Th.W. de, and Kleintjens, L.A., Pressure pulsed induced critical scattering Spinodal and binodal curves for the system polystyrene + methylcyclohexane (exp. data by Th.W. de Loos), Fluid Phase Equil, 83, 383, 1993. 

Since Freeman and Rowlinson s publication [31] the amount of experimental information in the system -alkane/polyethylene has increased considerably. Papers by Nakajima et al. [34-36], Kodama and Swinton [37, 38], Koningsveld et al. [39], and Kennis et al. [40] deal with the molar mass dependence of the LCM in terms of cloud-point curves of linear polyethylene in various alkanes, ranging from w-pentane to n-tridecane, and in binary mixtures of -alkanes. Galina et al. [41] reported a spinodal and a cloud-point curve for a polyethylene sample (M = 177 kg mol in -hexane, measured with Gordon s Pulse Induced Critical Scattering technique [42, 43]. 

To check the viability of Eq. (16) the system di-phenylether/branched polyethylene has been used as a test case [78]. Experimental liquid-liquid critical points, measured with the phase volume ratio method [44] for samples varying in degree of branching, may serve the purpose together with some experimental spi-nodal temperatures, measured with the Pulse-Induced Critical Scattering technique of Gordon et al. [41 3]. The data were used to calculate values for the parameters in Eqs. (17) and (18) (details of the fitting procedure can be found in [54]). 

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