Surface magnetisation

An experiment to measure the asymmetry as a function of applied magnetic field at different values of strain was set up by Sun and O Handley (1991). It is shown in fig. 7. From the measured asymmetric spin-orbit scattering, A, the surface magnetisation, Afsurf is determined as... 

Experimental studies of filled rubbers are complicated by several things, such as the effect of the magnetic susceptibility of the filler, the effect of free radicals present at the surface of carbon black, the complex shape of the decay of the transverse magnetisation relaxation of elastomeric materials due to the complex origin of the relaxation function itself [20, 36, 63-66], and the structural heterogeneity of rubbery materials. 

H NMR transverse magnetisation relaxation experiments have been used to characterise the interactions between NR, isoprene rubber, BR, EPDM and polyethylacrylate rubbers with hydrophilic silica and silicas modified with coupling agents [124-129]. These studies showed that the physical interactions and the structures of the physical networks in rubbers filled with carbon black and rubbers filled with silicas are very similar. In both cases the principal mechanism behind the formation of the bound rubber is physical adsorption of rubber molecules onto the filler surface. 

Figure 14.5 Two-dimensional magnetisation-exchange spectra of a SBR sample recorded with the three-pulse sequence of Figure 14.4b. Different mixing times have been used tm = 2.5 ms, (a) 5 ms, (b) 15 ms, (c) and 30 ms (d). The 2D surface representation for tm=30 ms in (e) shows that all cross-peaks are positive [36]...

The vapour pressure of a plane surface of a pure liquid in contact with vapour of the same composition depends only on the temperature, p=f(T)> provided that the disturbing effects of gravity, surface tension, electrification, magnetisation, etc. (see 15-18.VIIIL) are excluded, and it is independent of the relative amounts of liquid and vapour. It depends on the composition of the liquid, e.g. at 0 C. the vapour pressures in mm. Hg of different liquids are ... 

The NMR spectrum is a curve showing the variation in magnetisation as a function of frequency, the latter being expressed as a relative value (ppm) in relation to a reference frequency. For a given isotope, at least for 1/2 spin nuclei (by far the most commonly encountered), the surface of the signal is proportional to the number of nuclei resonating at this frequency. For example, in the toluene proton spectrum, the surface of the signal CH3 will be... 

Fig. 27 Determination of the diffusion coefficient of partially per-deuterated methanol into a water (D2O) swollen PNIPAAm gel at 21 °C. The increase of magnetisation of a thin sample layer (thickness about 100 pm) is measured. The layer is located at a distance of 4.8 mm from the sample surface...

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