Ubbelhode viscometer

Calculations. For determination of the intrinsic viscosity [ti] the prepared pectins were solved in an 0.1 M phosphate buffer with pH 6.0. The relative viscosity was determined by a glass. Ubbelhode viscometer at 25 0.1 °C. The flow time of solvent (L) was 81.8 seconds. At least six pectin solutions with different concentrations were measured in a way that their flow times (ts) comply the order 1.2to[Pg.528]

Materials. Four samples of sodium poly(styrenesulfonate) (NaPSS) prepared by sulfonation of polystyrenes with narrow molecular weight distribution were purchased from Pressure Chemical Co. The characteristics of the samples, according to the manufacturer, are listed in Table I. The intrinsic viscosities of NaPSS in aqueous NaCl solution were measured using an Ubbelhode viscometer at 25 °C. 

Acknowledgement We wish to thank Prof. G. Berry, Prof. J. D. Ferry, Prof. W. W. Graessley, Prof. N. Hadjichristidis, Dr. D. Pearson and Prof. J. Schrag for their advice regarding the practical limitations of Ubbelhode viscometers for the measurement of concentrated polymer solutions. We also wish to thank Dr. R. Quirk for his comments and information. 

Since the density of a very dilute solution is approximately the same as the solvent itself, the relative viscosity (r r = r /r s) can be taken as the ratio of the time required for a given volume of fluid to flow through an Ubbelhode viscometer. The specific viscosity (r[sp) is then given by... 

Viscosity. The viscosity measurements of the PMMA graft chains obtained by hydrolysis of graft copolymer were carried out in benzene at 30°C using an Ubbelhode viscometer, and the number average molecular weight of the grafted chain was calculated using the equation(25) ... 

Dilute solution viscosities of most polymers were measured at room temperature in p-chlorophenol/1,2-dichloroethane (50/50 by weight), using an Ubbelhode viscometer. For samples containing HQ/RO, the viscosities were measured at 50°C in pentafluorophenol. In any case the molecular weight or viscosity of each sample was reported as nSR/c, or reduced viscosity, at 0.5 g/dl in the units of ol/g. 

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). 

Viscosities were measured with a Cannon-Ubbelhode viscometer at 30.0°C in a bath regulated to within 0.01 °C. 

In most experiments, dilute solutions of about 1% polymer are made up. The quantity r/rei should be about 1.6 for the highest concentration used. The most frequently used instrument is the Ubbelhode viscometer, which equalizes the pressure above and below the capillary. 

The viscosity was determined with a thermostated Ubbelhode viscometer with an accuracy to 0.5%. 

The viscosities of aqueous solutions of PGA were determined with an Ubbelhode capillary viscometer at 298 K in the same concentration range as the density measurements. The temperature of the water bath was maintained to 0.05K. 

Figure 4.21 Glass viscometers, (a) Ostwald viscometer (b) Ubbelhode suspended-level viscometer (c) A modified suspended-level viscometer (see text for description).

For both GPC/LALLS and intrinsic viscosity measurements, Burdick Jackson distilled-in-glass, UV grade tetrahydrofuran (THF) was used. GPC/LALLS e q>eriments were conducted at a constant, pulse-free solvent flow-rate of 1-0 ml/min. Solute concentrations were 0.1% (w/vol.) and the volume of injected solution ranged from 0.3 ml to 0.5 ml. Intrinsic viscosities for CTC in THF were measured at 25 C in a Cannon-Ubbelhode four-bulb shear dilution capillary viscometer (Size 50). Kinetic energy corrections were negligible eind the data were corrected for sheeu effects by extrapolation of n /c to zero shear rate (10). 

Say we are interested in a fast, approximate molecular weight of a polystyrene sample. We dissolve 0.10 g of the polymer in 100 ml of butanone and measure the flow times at 25°C in an Ubbelhode capillary viscometer. The results are... 

Inherent viscosities (I.V.) of the polymers were measured using a 50 bore Cannon-Ubbelhode dilution viscometer immersed in a thermostatically controlled water bath at 25 C at a concentration of 0.025 gms/25 ml. 

Intrinsic viscosities (17) were determined using a Ubbelhode type capillary viscometer and extrapolating to zero shear I4J. Molecular weights for DNA samples were derived from sedimentation constant and intrinsic obesity measurements according to the relations given by Eigner and Doty [5]. 

Viscosity measurements of diluted HPMC solutions were performed by Ubbelhode capillary viscometer (flow time for bidistilled water was 195.6 s at 30 °C), immersed in a water thermostat at 30 °C. Proper volumes of 3.0 g/lOOcm SDS solution were added to 15 cm of HPMC solution in order to obtain desired SDS concentration. For each solution, 3-5 viscosity measurements were taken and average values were calculated. The results were expressed as specific, reduced and intrinsic viscosity. 

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