Polystyrene viscosity measurements

The results of intrinsic viscosity measurements for four polymer-solvent systems made at the -temperature of each are shown in Fig. 141. The four systems and their -temperatures are polyisobutylene in benzene at 24°C, polystyrene in cyclohexane at 34°C, poly-(di-methylsiloxane) in methyl ethyl ketone at 20°C, and cellulose tricapry-late in 7-phenylpropyl alcohol at 48°C. In each case a series of poly-... 

Fig. 2. Effect of the uv detector noise on the estimation of the molecular weight as function of elution volume for a narrow polystyrene standard. The symbols represent molecular weights obtained using the universal calibration and viscosity measurements on collected fractions...

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. 

Alfrey, T., A. Bartovics, and H. Mark Comparative Osmotic and Viscosity Measurements with Polystyrene Fractions. J. Amer. chem. Soc. 65, 2319 (1943). 

It is now generally accepted that the GPC retention volume is a function of the product M tf, independent of the nature or structure of the polymer 46, 47) though Pannell 45) found that it failed to correlate the elution behaviour of his highly branched polystyrenes, it may be accepted that M rf will be determinable from GPC retention volumes for moderately branched polymers. To estimate branching, it is necessary to separate this product so that M and [rf are both known and the relation between them can then be used, subject to the uncertainties mentioned in Subsection 9.2.2, for this purpose. It is usual to measure rf rather than M in order to make the separation, as it is easier. The combination of GPC and intrinsic viscosity measurements is now the most usual method for studying long branching. 

Because sample homogeneity is particularly important for a Standard Reference Material, it was carefully assessed for both polystyrenes using solution viscosity, a measure of molecular weight, as an index. There is essentially no variation with location within the lot, or from pellet to pellet, within the limits of error of the viscosity measurements. Viscosity measurements may be made with a standard deviation of a single determination of about 0.3%. 

Dawkins and Taylor109 dispersed poly(methyl methacrylate) (PMMA) or polystyrene (PS) particles in n-alkanes stabilized by AB block copolymers of styrene and dimethyl-siloxane. In these cases, styrene blocks act as anchors and dimethylsiloxane blocks give a surface layer. The thickness 6 of the dimethylsiloxane layer was determined by viscosity measurements as a function of the molecular weight of dimethylsiloxane blocks. 

The rotational correlation times of a benzene solution of a nitroxide imbibed in polystyrene of varied crosslinking density and the analogous compound covalently attached to the chains of the crosslinked polystyrene were measured. In the latter case the modified polystyrene matrix was also equilibrated with benzene. An estimate of the influence of crosslinking density on the internal viscosity can be obtained... 

Research grade poly(styrene-b-butadiene-b-styrene), designated as TR-41-1647, TR-41-1648, and TR-41-1649, were received from Shell Development Co. These block copolymers contain 26.8, 29.3, and 48.2 wt% polystyrene (PS), respectively. The average molecular weights, determined by intrinsic viscosity measurements in toluene at 30°C, were found to be 7-36-6, 16-78-16, and 14-30-14 in units of thousands. The microstructure of polybutadiene (PB) blocks was found to contain about 40 mol% in cis-1,4, 50% in trans-1,4, and 10% in 1,2 units. 

The polystyrene sizes were not the sizes commonly assumed for polystyrenes based on extended chains, but instead were determined from the viscosities (measured by Arro Labs, Joliet, Illinois) as described in Reference 8. Other types of standards and methods of calibration have been used for the GPC of residua samples (3, 9), including the Benoit universal calibration (10). However, these all relate the molecular weight to elution time, and for this work a molecular-size-elution-time relationship was needed. The polystyrene and n-alkane sizes were used to construct a In size vs. elution time calibration that was fit to a fourth-order polynomial to give a smooth curve. 

The zero shear viscosities of these randomly branched polystyrenes were measured and compared with those of linear polystyrenes and it was found that t]0 for all of the branched polymers were far lower than that of linear homologues of the same overall molecular weight. In addition, a scaling of fJo was observed for the first two generations of each branched series of... 

Curing the quinone-sensitized photooxidative degradation of polystyrene film and its solution in benzene,an initial rapid decrease of average molecular weight has been observed by viscosity measurement (Fig.8) and GFC (Fig.9) (10 ). 

Problem 3.26 Viscosity measurements on polystyrene fractions of different molecular weights in benzene at 20°C yielded the following values for intrinsic viscosities. 

The atactic polystyrene is the polymer which has served the most for the study of the statistical behaviour of polymers in solution. The first significant viscosity measurements were made with rubbers and celluloses (1930), but it was very quickly recognized that polystyrene is a material which is especially suited for precise experiments. This polymer is perfectly linear and it is possible to obtain samples of molecular masses from 104, to 107 dalton, with an acceptable dispersion. Good solvents for polystyrene are benzene, carbon disulphide, and so on. Cyclohexane is also a solvent of polystyrene, but is not as good. 

The melt behavior of sulfonated polystyrene ionomers was studied by Lundberg and coworkers41. As was shown in the case of a sulfonated elastomer30, sulfonation of polystyrene leads to an increase in the melt viscosity (measured at 250 °C) of the SPS upon neutralization, indicating increased association of the sodium poly-(salt). A sudden jump of the melt viscosity occurs at the point of complete neutralization, where a critical concentration of Na polystyrenesulfonate is reached, apparently resulting in a sharp phase separation between the ionic and hydrophobic domains (Figure 5). 

The following data were obtained for polystyrene dissolved in cyclohexane, when viscosity measurements were made at the 0 temperature of 308 K (solvent flow time, = 100 s). 

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