Kinetic small-angle neutron scattering

Keywords blend miscibility, interaction energy, phase diagram, phase separation kinetics, small angle neutron scattering (SANS), Hory-Huggins-Staverman equation, free energy of mixing, upper critical solution temperature (UCST), lower critical solution temperature (LCST). 

Abstract In this chapter we discuss practical techniques and instrumentation used in experimental measurements of kinetic and equilibrium isotope effects. After describing methods to determine IE s on rate constants, brief treatments of mass spectrometry and isotope ratio mass spectrometry, NMR measurements of isotope effects, the use of radio-isotopes, techniques to determine vapor pressure and other equilibrium IE s, and IE s in small angle neutron scattering are presented. 

Small angle neutron scattering instruments are specifically designed to examine disordered materials, such as to determine hydration structures during hydrate formation (Koh et al., 2000 Buchanan et al., 2005 Thompson et al., 2006), or to study kinetic inhibitor adsorption onto a hydrate surface (Hutter et al., 2000 King et al., 2000). 

In TEM studies by Fernandez, et al. (9) on thin-sliced materials, it was shown that early in the polymerization of the styrene in PB/PS IPN s the domains tended to be spherical, while later in the polymerization the domains tended to be ellipsoidal in nature. The latter were modeled as irregularly shaped cylinders, which resemble ellipsoidal structures on thin sectioning. In more recent experiments involving small-angle neutron scattering, SANS, it was concluded that the phase separation involved a mixture of nucleation and growth, and spinodal decomposition kinetics (10). 

Poel, 1986Poe2] Small Angle Neutrons Scattering (SANS) < 750°C, 47 at.% Ni, < 8 at.% Fe, kinetics of short range ordering... 

Sinha, S.K., Fretoft, T. and Kjems, J.K. (1984). Observations of power law correlations in silica particle aggregates by small-angle neutron scattering. In Kinetics of Aggregation and Gelation, Family, F. and Landau, D.P. (eds). North-Holland, New York, pp. 87-90. 

Kinetic Analysis of Cryotropic Gelation of Poly(Vinyl Alcohol)/Water Solutions by Small-Angle Neutron Scattering... 

PEN/PET Deuterated PET/small-angle neutron scattering/effects of temperature and heating time/reaction kinetics/NMR Collins et al. 2001... 

These properties are still poorly understood on the whole. Further studies will be needed to clarify the mechanisms involved in these reactions and understand the structure of the latexes produced. In particular, it will be important to determine which parameters control reaction kinetics (constants of propagation, termination, and so on), latex stabilisation mechanisms and macromolecule conformations within particles. The latter question may be resolved using Small Angle Neutron Scattering (SANS). On an industrial scale, the process is of limited profitability due to the high surfactant concentrations required, and the relatively low monomer concentration (in the case of spherical... 

Fig. 2.16. Variation of the radius of the water pool in the iso-octane-AOT-water inverted micellar system. The water pool radius was estimated using Small angle X-ray scattering open squares), Small angle neutron scattering crosses), kinetic studies using hydrated electron probe open circles) (reproduced with permission from [411])...

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