Intrinsic viscosity, measurements

Intrinsic viscosities were measured at 25 °C, in methylene chloride... 

Harding, Stephen E. 1997b. The Viscosity Intrinsic of Biological Macromolecules. Progress in Measurement, Interpretation and Application to Structure in Dilute Solution. Progress in Biophysical Molecules Biological 68, 207-262. 

Low molecular weight solids were dispersed in KBr pellets polymer films were cast from CHCI3. Intrinsic viscosities were measured by standard procedures using a Cannon Ubbelohde dilution viscometer. 

With the aim to establish an [rj]-M relation (Equation (36)) for universal calibration and for the determination of the persistence length, intrinsic viscosities were measured with an Ubbelohde capillary viscometer. The respective data are also included in Table 3. 

The solvents and coupling reagents were reagent grade materials. The tricaprylmethylammonium chloride (Adogen 464) was not purified further. Intrinsic viscosities were measured in chloroform at 25. Infrared spectra for hydroxyl analysis were measured on 2.5% solutions in carbon disulfide (vs. carbon disulfide2.in a cell with a 1.00 cm path length. The absorbance at 3610 cm was subtracted from a similar spectrum of 2 which had been quantitatively acetylated. 

This study addresses two questions 1) Is polymer aggregation in solutions directly related to solvent quality 2) If not, does solvent quality exert an effect on the viscosity of semidilute solutions separate from the effect of aggregation The copolymer poly(vinylbutyral) (PVB) was chosen for this investigation. PVB is known to aggregate in several solvents (IS). Light scattering and intrinsic viscosity measurements were used to assess solvent quality. Viscosities were measured at one concentration in three solvents and temperatures from 25 to 55 C. 

Viscometry. Intrinsic viscosity. Kinematic viscosities (v=rj/p, where tj is the viscosity) were measured in a Cannon-Ubbelohde capillary viscometer. At least four concentrations, covering the relative viscosity range where the subscript s denotes the solvent) from about 1.8 to 1.2 were used to construct Schul -Blaschke plots. These plots of versus where... 

The experimental determination of polymer intrinsic viscosity is done through the measurement of polymer solution viscosity. The connotation of intrinsic viscosity [hi/ however, is very different from the usual sense of fluid viscosity. Intrinsic viscosity, or sometimes called the limiting viscosity number, carries a far more reaching significance of providing the size and MW information of the polymer molecule. Unlike the fluid viscosity, vdiich is commonly reported in the poise or centipoise units, the [h] value is reported in the dimension of inverse concentration xinits of dl/g, for exanple. The value of [hi for a linear polymer in a specific solvent is related to the polymer molecular weight (M) through the Mark-Houwink equation ... 

In all cases, intrinsic viscosities were measured at 25 C in constant temperature baths controlled to +0.1°C or better, using suspended level Ubbelohde dilution viscometers with solvent flow times of at least 100 sec.. No kinetic energy corrections were made. Solution flow times were measured at four concentrations for each sample, and intrinsic viscosities were obtained from the classical double extrapolation of hg /c vs. c and (In hj.)/c vs. c to a single intercept value. Concentration ranges were varied somewhat with the molecular weights of the samples, but were chosen such that both functions were straight lines in all cases. 

Various molecular weight fractions of cellulose nitrate were dissolved in acetone and the intrinsic viscosity was measured at 25°C ... 

Melt Viscosity. Figure 9 compares the relationship between melt viscosity and intrinsic viscosity of PET obtained by polycondensations using various additives and that of PET manufactured by the conventional method. The melt viscosity was measured with a rotary viscometer after the sample was melted at 280°C in a nitrogen stream. There is no difference in this relationship between the two kinds of PET. 

Physical Measurements. Intrinsic Viscosities. Intrinsic viscosities were obtained using dilute solution viscometry (Cannon-Ubbelohde viscometers). 

GPC with an on-line viscometer can be used instead of a LALLS detector to analyze branched polymers. In this case the intrinsic viscosity is measured so that the Mark-Houwink parameters are not needed. It is complementary to the LALLS instrument in intrinsic viscosities. 

Shape effect of PFPE molecules or magnetic particles in suspension, including agglomeration phenomena at low concentration, interaction among these particles, and effects of floes can be examined via solution viscosity (r ) measurement. For a very dilute polymer solution [108], there is no interaction among polymer molecules, and the solution viscosity results from the contribution of the solvent plus the contribution of the individual polymer molecules. The intrinsic viscosity, therefore, is a measure of the hydrodynamic volume of a polymer molecule as well as the particle aspect ratio. Figure 1.24 shows the determination of the intrinsic viscosity for Zdol4000 in three different solvents. 

Brabender Processing. In another series of tests, two commercial (stabilized) resins, unstabilized polypropylene, and the latter with 0.4% DLTDP + 0.1% PPP were masticated for five minutes at 50 r.p.m. and 180 °C. in the Brabender apparatus, then mixed for 25 minutes at 150 r.p.m. and 200°-215°C. Meter-gram torque readings were plotted over the mixing cycle along with temperature, and intrinsic viscosity was measured for each formulation before and after processing. 

Intrinsic viscosities were measured in benzene at 30 °C. using a Cannon-Ubbelohde viscometer with flow time greater than 200 sec. Results are expressed in deciliters/gram and for poly (methyl methacrylate) (PMMA) were converted to molecular weights by the following equations (4, 12) ... 

However, to illustrate the effect of solvent on viscosity, we measured the intrinsic viscosities of three copolymers in a polar solvent—benzyl alcohol at 80°C. The two solvents are compared in Table B. Although the intrinsic viscosities of the hydroxyl-containing copolymers are similar in the two solvents, the value for pure polystyrene is much reduced in the polar solvent. This provides indirect evidence for the existence of a smaller coil volume for the copolymer molecules in the nonpolar solvent. 

Viscosity Determination. Viscosities were measured in 0.5 M cupriethylene-diamine (CED) at 25 °C with a Cannon-Fenske viscometer, size 100 (7). From these measurements, the intrinsic viscosity was determined according to the American Society for Testing and Materials (ASTM) Standard D1795. Values for the viscosity-average degree of polymerization were obtained by multiplying the intrinsic viscosity by 190. 

The Mark-Houwink relation for polypropylene in o-dichlorobenzene at 130°C was calibrated as follows. A series of sharp fractions of the polymer was obtained by fractionation, and the molecular weight of each fraction was determined by membrane osmometry in toluene at 90"C. The samples were then dissolved in o-dichlorobenzene at I30°C and their intrinsic viscosities ([ ]) were measured. The resulting data fitted an expression of the form... 

Our ThFFF channel is similar to the model TlOO Thermal Fractionator (FFFractionation, Inc., Salt Lake City, UT), with a channel thickness of 0.10 mm. When the carrier liquid was tetrahydrofuran (THF) or cyclohexane, a UV monitor set at 254 nm was used for sample detection when toluene was the carrier liquid, a refractive index monitor was used instead. The temperature difference was 60.0 K and the cold wall temperature was 298.2 K. Intrinsic viscosities were measured with a CannonFenske ASTM-25 viscometer obtained from Fisher Scientific (Santa Clara, CA). Viscosities were measured in a thermostated temperature bath set at T g. All solvents were high-performance liquid chromatography grade. 

Intrinsic viscosities were measured using diisoibutylene solvent at 20 °C and aUbbe-k de Viscometer. 

To show this structure viscosity we measured the intrinsic viscosity of the same polymer solutions in viscometers with different capillary lumen (Table III). The lumen had a strong influence on the measured values the greater it was, the smaller were the figiu es for the intrinsic viscosity. 

Molecular characterization of the polymers consisted of intrinsic viscosity measurements and size exclusion chromatography. The intrinsic viscosities were measured in a solvent mixture of phenol and o-dichlorobenzene using Cannon-Ubbelhode viscometers. Polyethylene terephthalate equivalent molecular weights were determined using a Waters 244 GPC in a solvent mixture of methylene chloride and hexafluoroisopropanol. The results from NMR, DSC, and molecular characterization are summarized in Table I. Techniques for the dynamic x-ray diffraction studies are described elsewhere (2). 

Soluble polymers were run through a gel permeation chromatograph. Polyst3ncene fractions of known molecular weight were run also and their intrinsic viscosities were measured. The universal calibration technique was used in conjunction with a computer program to calculate the number average molecular weight, Mq, of the polyurethane. 

Size exclusion chromatographic analyses in tetrahydrofuran were performed with a Waters 150C GPC with six p-Styragel columns having a continuous porosity range of 10 - 10 k and also with the Perkin- Elmer Model 601 HPLC with three p-Styragel columns (10 , lO", 10 A) after calibration with standard polystyrene samples. Intrinsic viscosities were measured In chloroform at 30.0 C and in tetrahydrofuran at 40°C using an Ubbelohde type viscometer. 

Problem 3.13 For a fractionated polyisobutylene sample of molecular weight 1.5x10 the intrinsic viscosity was measured in cyclohexane at 30°C (good solvent) and in benzene at 24°C (theta solvent). The ratio of these two intrinsic viscosities yielded the factor o , by which the volume of the molecule in cyclohexane at 30°C is enlarged relative to the volume of the unperturbed molecule, as 4.03. Evaluate the total thermodynamic interaction — k) for polyisobutylene-cyclohexane at 30°C. Use the observed relation for polyisobutylene between molecular weight (Mo) and the unperturbed root-mean-square end-to-end distance given... 

Problem 3.25 For a fractionated sample of cis-1,4-polybutadiene of molecular weight 123x10 intrinsic viscosities were measured [30] in three different solvents at respective theta temperatures. From the results given below determine the variation of the unperturbed dimensions of the polymer molecule with temperature. 

Polymers that have been suggested for mobility control in oil reservoirs include polyacrylamides, hydroxy ethyl cellulose, and modified polysaccharides which are produced either by fermentation or by more conventional chemical processes. In this paper the solution properties of these polymers are presented and compared for tertiary oil recovery applications. Among the properties discussed are non-Newtonian character for different environmental conditions (electrolytes and temperature), filterability, and long term stability. The behavior of these water soluble polymers in solution can be correlated with the effective molecular size which can be measured by the intrinsic viscosity technique. A low-shear capillary viscometer with a high precision and a capability of covering low shear rates (such as 10 sec - - for a 10 cp fluid) has been designed to measure the viscosities. The measurement of viscosities at such slow flow conditions is necessitated... 

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