The state of solution of a technical viscose is of both theoretical and technical interest. The existing assumptions may be divided into two general theories. These two opposing theories are concerned, to put it simply, with whether cellulose xanthate is more or less molecularly dispersed or is only a dispersion of micelles and bigger aggregates. After a short survey of the more essential and newer contributions a particle spectrum for describing the state of solution of a spinnable viscose is proposed. Furthermore, the assumption is made that about 60% of the cellulose may behave as a molecular dispersion, making possible the determination of molecular weight and other molecular parameters. The frequency distribution of micelles, bigger aggregates, and fiber fragments, derived from a stepwise disintegration process, may follow a Gaussian curve. This hypothetical frequency distribution in our particle spectrum is in agreement with known observations. The microscopic particles, affecting technical operations, can be determined directly by particle counting or indirectly by filterability determinations. After mentioning a new technique for obtaining filter values of unusually high accuracy despite the inhomogeneity of the filter materials, some results of filterability tests combined with gel particle counting are reported.
The spin-lattice relaxation rates (1/T1) were measured at 94.1 MHz for six peaks in the 19F NMR spectrum of the perfluorochemical blood substitute fluosol-DA, which contains a mixed emulsion of perfluorodecalin and perfluorotripropylamine. Each of these rates increased linearly with the percentage of oxygen dissolved in the emulsion. Relative values of the linear increase for different peaks established that, for perfluorotripropylamine in the mixed emulsion, the oxygen-fluorocarbon interaction is loosely but preferentially oriented in a manner similar to that previously established for other pure fluorocarbons. The uncertainty in the oxygen level estimated from T1 measurements is somewhat less than 5% O2 and it is thus established that quantitative non-invasive oxygenation measurements can be made to sufficient precision by this approach, using fluosol-DA and 19F spin-lattice relaxation.
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