Small-angle Neutron

Other techniques such as X-ray diffusion or small angle neutron diffusion are also used in attempts to describe the size and form of asphaltenes in crude oil. It is generally believed that asphaltenes have the approximate form of very flat ellipsoids whose thicknesses are on the order of one nanometer and diameters of several dozen nanometers. 

SANS Small-angle neutron scattering [175, 176] Thermal or cold neutrons are scattered elastically or inelastically Incident-Beam Spectroscopy Surface vibrational states, pore size distribution suspension structure... 

The polymer concentration profile has been measured by small-angle neutron scattering from polymers adsorbed onto colloidal particles [70,71] or porous media [72] and from flat surfaces with neutron reflectivity [73] and optical reflectometry [74]. The fraction of segments bound to the solid surface is nicely revealed in NMR studies [75], infrared spectroscopy [76], and electron spin resonance [77]. An example of the concentration profile obtained by inverting neutron scattering measurements appears in Fig. XI-7, showing a typical surface volume fraction of 0.25 and layer thickness of 10-15 nm. The profile decays rapidly and monotonically but does not exhibit power-law scaling [70]. 

The structure of microemulsions have been studied by a variety of experimental means. Scattering experiments yield the droplet size or persistence length (3-6 nm) for nonspherical phases. Small-angle neutron scattering (SANS) [123] and x-ray scattering [124] experiments are appropriate however, the isotopic substitution of D2O for H2O... 

Hamley I W, Garnett S, Luckhurst G R, Roskilly S J, Pedersen J S, Richardson R M and Seddon J M 1996 Orientational ordering in the nematic phase of a thermotropic liquid crystal A small angle neutron scattering study J. Chem. Phys. 104 10 046-54... 

Mortensen K 1996 Structural studies of PEO-PPO-PEO triblock copolymers, their micellar aggregates and mesophases a small-angle neutron scattering study J. Phys. Condens Matters A103-A104... 

In addition to the above techniques, inverse gas chromatography, swelling experiments, tensile tests, mechanical analyses, and small-angle neutron scattering have been used to determine the cross-link density of cured networks (240—245). Si soHd-state nmr and chemical degradation methods have been used to characterize cured networks stmcturaHy (246). H- and H-nmr and spin echo experiments have been used to study the dynamics of cured sihcone networks (247—250). 

Kieffer, J., Investigation of the transitional pore stmeture of activated carbon fibers by small-angle neutron scattering, J. Appl. Phys., 1992, 72(12), 5649 5656. 

F. Boue, J. P. Ambroise, R. Bellisent, P. Pfeuty. Equilibrium polymerization of hquid sulfur from small-angle neutron scattering of sulfur solutions. J Physique 7 2 969-980, 1984. 

K. V. Schubert, R. Strey. Small-angle neutron scattering from microemulsion near the disorder Une in water/formamide-octane-C,E systems. J Chem Phys 95 8532-8545, 1991. 

Bone, F. Transient Relaxation Mechanisms in Elongated Melts and Rubbers Investigated by Small Angle Neutron Scattering. Vol. 82, pp. 47— 103. 

Richards, R. W. Small Angle Neutron Scattering from Block Copolymers. Vol. 71, pp. 1 to 40. 

Cetyltrimethylammonium 4-vinylbenzoate (33) forms rod-like micelles that can be stabilized by radical polymerization. The resulting structure, was observed by small-angle neutron scattering to retain its original rod-like architecture and showed enhanced thermal stability and did not dissociate upon dilution. 

This state of partial deformation has been determined recently by small angle neutron scattering [194] and has been a favorite subject of investigation in the... 

SANS. See Small-angle neutron scattering (SANS)... 

Silylated diamines, 156, 187-188 Silylated monomers, 72 Silylation, distillation and, 338 6NT6 alternating polyesteramide, synthesizing, 189-190 6,6 -linked polymers, 480 Size exclusion chromatography (SEC) analyses, 90, 490 Slabstock foam, 233-234 Slow monomer addition, 57 Small-angle neutron scattering (SANS), 282... 

The aggregation numbers of sodium octyl, decyl, dodecyl, and tetradecyl sulfates at temperatures between 20°C and 60°C have been studied by Vass by small-angle neutron scattering [130]. Table 22 shows the aggregation numbers of some alcohol and alcohol ether sulfates. 

Small angle neutron scattering (SANS) involves firing neutrons at a sample and measuring the angle through which they are scattered. This allows the momentum transfer, Q, to be determined according to the equation ... 

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