Intrinsic viscosity determination

Since viscometer drainage times are typically on the order of a few hundred seconds, intrinsic viscosity experiments provide a rapid method for evaluating the molecular weight of a polymer. A limitation of the method is that the Mark-Houwink coefficients must be established for the particular system under consideration by calibration with samples of known molecular weight. The speed with which intrinsic viscosity determinations can be made offsets the need for prior calibration, especially when a particular polymer is going to be characterized routinely by this method. 

Curvale, R.A., Cesco, J.C. 2009. Intrinsic viscosity determination by "single-point" and "double-point" equations. Applied Rheology 19, 5, 53347. 

Intrinsic viscosity determined in m-cresol at 3 °C insoluble in m-cresol... 

Figure 3.8 Intrinsic viscosity determination for the data in Tables 3.3 and 3.4...

Due to the high sensitivity of the viscometer, accurate readings of viscosity responses can be made with sample h gi values much less than 1.1. Therefore, saitple solutions of very low concentration can be analyzed in the viscometer to produce a single point intrinsic viscosity determination without the need of concentration extrapolation. As shown in Figure 7 for a polystyrene saitple, any h- u determination at the value of... 

The polymer samples studied here fall into three distinct categories. Data from two sample populations have been combined in the SAN copolymer study. A group of SAN materials having compositions ranging from 42 (wt)% AN to 82% AN were polymerized and characterized quite some time ago (1972), with intrinsic viscosities determined only in DMF. Very recently, a second group of SAN s with compositions from 5 (wt)% to 48% AN, as well as one sample of polystyrene (0% AN), were polymerized and characterized, with intrinsic viscosities determined in DMF, THF, and MEK. These two populations are differentiated in the Results section by the designations "old data" and "new data". The third category of samples is that of S/MA copolymers and S/MA/MM terpolymers, with intrinsic viscosities measured only in MEK. 

Materials. Ethylene-propylene copolymer, purified by Kumagawa (9) acetone extraction for 180 hours had a composition (determined by infrared) of C2 — 54.5, C3 = 45.5 wt %, and an intrinsic viscosity determined in toluene at 30°C of 1.38 X 10 cc/gram. Poly (vinyl alcohol) was Elvanol 50-42 from du Pont. The vinyl chloride monomer of Monte-catini Edison was 99.99% pure. Initiators used were ... 

Although the values of Intrinsic viscosity determined with a low shear viscometer are the only ones which truly represent the Intrinsic viscosity at high molecular weights, the results from the capillary viscometer are shown In Figure 7 to give an Indication of the effect of shear In the viscosity range of the study. The values of Intrinsic viscosity are different for the two types of viscometers, but the trend of Intrinsic viscosity versus conversion Is still the same. 

The Huggins equation has been used much more extensively and in Figure 1-6 intrinsic viscosity determination of mesquite seed gum, a galactose-mannose polymer, based on the equation is illustrated (Yoo et al., 1994). 

Figure 1-4 Intrinsic Viscosity Determination of Mesquite Seed Gum, a Galactose-Mannose Polymer, Based on the Huggins equation.

The molecular size of polybenzimidazoles has in the pertinent literature been expressed in terms of inherent (j7i h) or intrinsic ([ ]) viscosities, determined on sulfuric acid solutions or, less frequently, on solutions in formic acid or aprotic solvents. The effect of structure on viscosity behavior appears to be less pronounced than that of the polymerization methods used and of the monomer sensitivity to the employed reaction conditions. In general, melt polymerizations by Marvel s method give products with higher molecular mass than obtained in solution condensations, which may partly be due to increased end group reactivity and interaction at the much higher reaction temperatures encountered in the former process (Cf. Table 1). Furthermore, monomers like bis(phenoxycar-bonyl)ferrocene, diphenyl tetrafluoroterephthalate, or l,7-bis(phenoxycarbonyl)car-... 

For further information on the intrinsic viscosity determination in GPC, including the use of the light-scattering detector, see Ref. 8 and the entry GPC-SEC Viscometry from Multiangle Light Scattering. 

T = 65°C AIBN, 0.13% suspending agent, variable amounts depending on amount of rubber present, range 0.6-1.5% monomer conversion = 70% water/(rubber + monomer) = 1.4 and intrinsic viscosity determined in cyclohexanone at 30°C and expressed... 

Conditions as indicated in Figure 2 intrinsic viscosities determined in cyclohexane at 30°C and... 

T = 100°C elastomer in the initial styrene solution, 10% EPDM, type gf. initiator, tert-butyl peracetate, 0.09% and intrinsic viscosities determined in toluene at 30°C and expressed in dl/g... 

M, M, and the MWD. It can also provide complete control of GPC systems so that large numbers of samples can be run unattended and raw data can be automatically processed. Nowadays, the software used in GPC should be capable of providing special calculations for multidetection processing, special calibration routines, polymer branching, and intrinsic viscosity determination, etc. 

In the case of the nitrate, the data is taken from Sithola, et al. (17) while the CTC data is that determined by GPC/LALLS with CED intrinsic viscosities determined on the starting cellulose... 

Wetzel, F. H., Elliot, J. H., and Martin, A. F., Variable shear viscometers for cellulose intrinsic viscosity determination, Tappi J., 36, 564-571 (1953). 

Beer M. U., Wood P. J., Weisz J. 1999. A simple and rapid method for evaluation of Mark-Houwink-Sakurada constants of linear random coil polysaccharides using molecular weight and intrinsic viscosity determined by high performance size exclusion chromatography Application to guar galactomannan. Carbohvdr. Polymers. 39, 377-380. 

Table 5 shows the given (determined by LALLS) and intrinsic viscosities determined from an online viscometer (Viscotek Model 110) and the measured determined by different calibration techniques for six samples. The deviations [(measured -given )/(given )] x 100 between... 

As mentioned in the previous paragraph, the calibration curve constructed by relating an average molar mass to the retention volume of a series of preferentially narrow MMD polymer samples can be used only for the determination of the MMD and average molar masses of an unknown sample of the same chemical composition and structure. The [rj] is the intrinsic viscosity determined experimentally. On the other hand, the use of the product M[rj],... 

Here the index i refers to a retention volume slice, C, is the polymer concentration measured by SEC for the slice i, Mi is MW determined by light-scattering analysis at retention volume slice i, and [77, ] is the intrinsic viscosity determined by viscometry of slice i. The constants k and a are the Mark-Houwink coefficients for a linear polymer of the same chemical composition My is the viscosity-average MW (Lue and Kwalk 2005). 

Intrinsic viscosity determinations (Fig.l) were carried out with xanthan solutions prepared in the presence or not of com steep liquor. The main results are summarized in Table III. 

PET contains a nucleating agent that assists in the molecular ciystallization." The extent of ciystallization and the intrinsic viscosity determine the balance between the container s stiffness at low and high temperatures." ... 

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