Viscometry applications

Many proteins and polymers have been analyzed on SynChropak GPC and CATSEC columns. Table 10.6 lists some of the published applications. The use of a surfactant to analyze the caseins in milk is illustrated in Eig. 10.12. Viruses have also been analyzed on SynChropak GPC columns, as seen in the chromatogram from Dr. Jerson Silva of the University of Illinois (Pig. 10.13). Dr. Nagy and Mr. Terwilliger analyzed cationic polymers on a series of CATSEC columns using differential viscometry as detection (Pig. 10.14) (9). 

Microgels are distinguished from linear and branched macromolecules by their fixed shape which limits the number of conformations of their network chains like in crosslinked polymers of macroscopic dimensions. The feature of microgels common with linear and branched macromolecules is their ability to form colloidal solutions. This property opens up a number of methods to analyze microgels such as viscometry and determination of molar mass which are not applicable to the characterization of other crosslinked polymers. 

A rather complete survey of the entire field of viscometry, including the mathematical relationships applicable to various types of instruments, has been made by Philippoff (P4). The problem of slip at the walls of rotational viscometers has been discussed by Mooney (M15) and Reiner (R4). Mori and Ototake (M17) presented the equations for calculation of the physical constants of Bingham-plastic materials from the relationship between an applied force and the rate of elongation of a rod of such a fluid. ... 

Figure 12.4 depicts schematically the experimental setup used in capillary flow studies. The primary application of the discussion that follows is in capillary viscometry, which is useful to die design. The ratio Rr/R should be greater than 10, so that the pressure drop due to the flow in the reservoir can be neglected.1 The reservoir radius cannot be too large, though, because the time required for uniform heating of the solid polymer load would be too long (see Fig. 5.6). Long heating cannot be used for sensitive polymers such as polyvinyl chloride (PVC), which readily degrade thermally.

Campanella, O.H., Peleg, M. 2002. Squeezing flow viscometry for nonelastic semisolid foods— theory and application. CRC Crit. Rev. Food Sci. Nutr. 42, 241-264. 

The application of refractive index and differential viscometer detection in SEC has been discussed by a number of authors [66-68]. Lew et al. presented the quantitative analysis of polyolefins by high-temperature SEC and dual refractive index-viscosity detection [69]. They applied a systematic approach for multidetector operation, assessed the effect of branching on the SEC calibration curve, and used a signal averaging procedure to better define intrinsic viscosity as a function of retention volume. The combination of SEC with refractive index, UV, and viscosity detectors was used to determine molar mass and functionality of polytetrahydrofuran simultaneously [70]. Long chain branching in EPDM copolymers by SEC-viscometry was analyzed by Chiantore et al. [71]. 

Viscosity measurements alone cannot be directly used in the Mark-Houwink-Sakurada equation to relate absolute viscosity and polymer molecular weight, since additional unknowns, K and a must be determined. Therefore, viscometry does not yield absolute molecular weight values it rather gives only a relative measure of polymer s molecular weight. Viscosity measurements based on the principle of mechanical shearing are also employed, most commonly with concentrated polymer solutions or undiluted polymer these methods, however, are more applicable to flow properties of polymers, not molecular weight determinations. 

Cotton fibers are single cells composed primarily ( 96%) of the polymer cellulose. In our laboratory (5), cotton fibers were dissolved directly in the solvent DMAC-LiCl. This procedure solubilizes fiber cell wall components directly without prior extraction or derivatization, processes that could lead to degradation of high MW components. MW determinations have been carried out by a size-exclusion chromatography (SEC) system using commercial columns and instrumentation with DMAC-LiCl as the mobile phase. Incorporation of viscometry and refractive index (RI) detectors (6) allowed application of the universal calibration concept (7) to obtain MW distributions (MWDs) based on well-characterized narrow-distribution polystyrene standards (5). The universal calibration concept used by incorporation of dual detectors bypasses the need for cellulose standards. There are no cellulose standards available. Polystyrene standards for a wide range of MWs dissolved readily in DMAC-0.5% LiCl with no activation necessary. 

Tests selected for routine condition monitoring vary between lubricant types and machine application tests. However, numerous tests are almost always performed (viscometry and elemental spectroscopy for instance) while others are optional or exception tests. An example oil analysis test scheme for a particular lubricant is illustrated in Fig. 5. The following are the types of tests commonly performed in laboratories ... 

Water soluble synthetic polyelectrolytes have attracted increasing attention in recent years, mainly because of their wide utility in industrial applications, and also because of their resemblance to biopolymers. PolyCmethacrylic acid), PMA, a wea)c polyelectrolyte, exhibits a mar)ced pH induced conformational transition. A wide variety of techniques have been employed to gain more information on the nature of the conformational transition of PMA, these techniques include viscometry, potential titrimetry,(1-5) Raman spectrometry,(6) calorimetry,(7-9) electrical conductometry,(10) dilatometry,(11) H NMR linewidth,(12) viscoelastic studies,(13) )cinetics of chemical reactions, (14) small-angle neutron scattering,(15) pH jump,(16,17) and fluorescent probing.(18-27)... 

But though rotational viscometry seems simple in principle, in practice it turns out there are so many sources of error to consider and corrections to be made that an operating rotational viscometer of good accuracy is a rather complicated apparatus. Many commercial instruments, operating either on the continuous rotation principle or the oscillating principle, are described in the monograph by Van Wazer et al. [2]. To illustrate the application of the principles of rotational viscometry to operating instruments, we shall examine the details of two instruments the first practical rotational viscometer, devised by Couette [9], and the Per ranti-Shirley cone-and-plate viscometer. 

Tanner (Tla) the treatment is analytical rather than numerical. The results having important applications in falling-ball viscometry. 

Selby, T. W., and Hunstad, N. A., The forced-ball viscometer and its application to the characterization of mineral oil systems. Presented at Symposium on Non-Newtonian Viscometry, sponsored jointly by Research Division III on Flow... 

Some of these less used systems have limited applications in specific areas and combine HPLC with, for instance, chemiluminescence techniques [48], viscometry [49], optical activity measurement [50], piezoelectric crystals for mass scanning [51], atomic absorption and emission spectrometry [52-54], photoacoustic monitors [55], nuclear magnetic resonance [56], electron spin resonance [57], Raman [58] and photoconductivity measurement [59]. Details on these and other innovative detection systems are presented in the review by Bruckner [60]. 

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