Viscose method

Mole fraction of hexane Experimental viscosity mPa-s Calculated viscosity method 1 mPa-s Calculated viscosity method 2 mPa-s Calculated viscosity method 3 mPa-s Molecular weight kg/kmol Density kg/m ... 

The molecular weight of SAN can be easily determined by either intrinsic viscosity or size-exclusion chromatography (sec). Relationships for both multipoint and single point viscosity methods are available (18,19). Two intrinsic viscosity and molecular weight relationships for azeotropic copolymers have been given (20,21) ... 

Vapor Viscosity Methods for prediction of vapor viscosity abound such that only the most accurate and generally used methods are included. 

A drawback of the Lagrangean artificial-viscosity method is that, if sufficient artificial viscosity is added to produce an oscillation-free distribution, the solution becomes fairly inaccurate because wave amplitudes are damped, and sharp discontinuities are smeared over an increasing number of grid points during computation. To overcome these deficiencies a variety of new methods have been developed since 1970. Flux-corrected transport (FCT) is a popular exponent in this area of development in computational fluid dynamics. FCT is generally applicable to finite difference schemes to solve continuity equations, and, according to Boris and Book (1976), its principles may be represented as follows. 

The significance of knowing the K and a values of fully hydrolyzed PVA is that molecular weight distribution data can be directly calculated using two methodologies. The first is the Mark-Houwink method, which requires prior knowledge of K and a values for fully hydrolyzed PVA and calibration standards such as PEG, PEO, or PSC. The second method is the intrinsic viscosity method. This method utilizes a simple ratio of the concentration signal to the specific... 

Ionic liquid System Cation Anion(s) Temperature, (X Conduc- tivity (k), mS cm Conduc- tivity method Viscosity (n), cP Viscosity method Density (p), gcm Density method Molar conductivity fAJ, cm iT mor Walden product (An) Ref. 

All these contradictions suggest that evidence of association obtained by the viscosity method is not always reliable. 

In principle all methods except viscosity measurement can be used to obtain absolute values of molar mass. Viscosity methods, by contrast, do not give absolute values, but rely on prior calibration using standards of known molar mass. The relationship between polymer solution viscosity and molar mass is merely empirical but the techniques are widely used because of their simplicity. All of the absolute methods are time-consuming and laborious and are not used on a routine basis. As well as the techniques already mentioned, there is the size-exclusion method of chromatography known as Gel-Permeation Chromatography (GPC). All of these methods are discussed in detail in the sections that follow. 

VISCOSITY METHODS OF DETERMINING RELATIVE MOLAR MASS... 

Saybolt Universal Seconds (SUS) are used to measure viscosity. The efflux time is the SUS required for 60 mL of a petroleum product to flow through the calibrated orifice of a Saybolt Universal viscometer, under carefully controlled temperature and as prescribed by test method ASTM D 88. This method has largely been replaced by the kinematic viscosity method. SUS is also called the SSU number (Seconds Saybolt Universal) or SSF number (Saybolt Seconds Furol). 

In general, upgrading concerns to those processes in which the API gravity of the crude oil or its viscosity decrease. Numerous reducing viscosity methods for heavy oil are currently commercialized [407], involving different means, such as physical methods... 

For the determination of Molecular weight of macromolecular compounds, the viscosity method was introduced by H. Staudinger... 

Rotational viscosity methods measure viscosity by measuring the torque required to rotate a spindle immersed in the fluid sample. 

Finally, a solvent viscosity method is often used to measure the molecular weight of many polymers such as PET, and this viscosity average molecular weight Is often close to the weight average molecular weight. 

Chen L, Ni E, Yang S, Peng H, Huang X, Fang X (1995) Reliable determination of molecular weights of polymers by GPC Intrinsic viscosity method. Fenxi Ceshi Xuebao 14 24-28... 

For most polymers there is a definite relationship between molecular weight and solution viscosity. The viscosity method of molecular-weight determination... 

Cation Anion Tempe- rature, (K) Conduc- tivity 1, mS cm Conduc- tivity method Viscosity m. <=p Viscosity method Density (P), g cm- Density method Molar conductivity (A), cm Q mof Walden product ( ) Ref... 

The effect of tetrahydrofuran on the polymerization of isoprene in hexane has been studied by Morton and co-workers (73, 74). The viscosity method was used to measure the degree of association. This was found to drop from 2 in pure hexane to about 1.3 with a ratio of THF to polyisoprenyllithium of 100 and dissociation of the polymer aggregates was complete at ratios of 500—700. With the reasonable assumption that the only species present in significant amounts were associated polymer molecules and etherates, it was possible to find the concentration of etherate present under all conditions. An equilibrium constant could be evaluated from the overall process... 

Redwood viscosity—method for determining the viscosity of petroleum products it is widely used in Europe, but has limited use in the U.S. The method is similar to Saybolt Universal viscosity viscosity values are reported as "Redwood seconds."... 

These two types of molecular weight averages are representative of the type called absolute methods, in that well-established thermodynamic equations can be used to convert the experimental data directly into a value of the molecular weight. However, some other methods require calibration. The most important of these indirect methods involves a measurement of the intrinsic viscosity. This quantity is a measure of the extent to which a polymer molecule increases the viscosity of the solvent in which it is dissolved. The viscosity method can be calibrated to yield a viscosity-average molecular weight, defined by... 

In addition to the API Technical Data Book and Gas Processors Suppliers Association (GPSA) methods [8], a new gas viscosity method is presented herein that may be used for a computer program application or a hand-calculation method ... 

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