Ratio of intrinsic viscosities

However, the quantity which is frequently discussed and related to specific branching models is the ratio of intrinsic viscosities at constant molecular weight )... 

Branching Parameter g from. SEC/LALLS. The effect of polymer branching upon the dilute solution configuration of polymers is conveniently expressed as the ratio of intrinsic viscosities of branched and linear polymers of the same chemical composition and molecular weight (35), i.e.. 

The experimental quantity from which information concerning branching is derived is g , the ratio of intrinsic viscosities of branched (subscript br) and linear (subscript 1) isomers ... 

Both of these relations are shown by the solid lines in Figure 3 for the ratio of intrinsic viscosities uncorrected for polydispersity and in Figure 4... 

Ratio of Intrinsic Viscosity of Polysaccharide Dispersions Heated (Enr ]fc) for 15 min at I2I°C and the Corresponding Unheated ([i)]c) Controls"... 

Note that this procedure need not be restricted to determination of MHS constants in the GPC solvent alone [221. The ratio of intrinsic viscosities in Eq. (3-76) can be measured in any solvent of choice as long as the w, and Jj values for the two polymer samples of interest are available from GPC in a common, other solvent. The first step in the procedure is the calculation of K and a in the GPC solvent as outlined in the preceding paragraph. The intrinsic viscosities of the same two polymers are also measured in a common other solvent. The data pertaining to this second solvent will be designated with prime superscripts to distinguish them from values in the GPC solvent. In the second solvent,... 

In 1953, Stockmayer and Fixman [2] observed that the ratio of hydrodynamic (Stokes) radii Rh), given by the symbol h, could also be used as a measure of branching. Although they presented their relationship as a ratio of intrinsic viscosities [see Eq. (11)], the relatively recent introduction of on-line dynamic light scattering (DLS) detectors... 

Ratio of intrinsic viscosity of antibiotic-DNA complex (r = 0 1) to that of DNA alone. Conditions of viscosity measurements 20 °C, 0.1 M tris-HCI buffer (pH 7.0). r is the ratio of bound antibiotic to total DNA-P. 

The solution viscosity of cyclic polymers is lower than those of their linear analogues. The viscosity of cyclic and linear PS was preferentially studied and compared in cyclohexane, a theta solvent. Quite similar intrinsic viscosity ratios, [>/]c/[>/]i/ were determined by several research groups for this system for instance, values of 0.64-0.70 depending on the molar mass, of 0.67, and of 0.65 are reported. However, at high molar masses (>20 000gmor ), the ratio of intrinsic viscosities was found to approach unity.A similar tendency was reported also for cyclic and linear poly(2-vinylpyridine) and polybutadiene. For cyclic and linear PDMS, the ratio of intrinsic viscosities, [r ]cl[h] i under 0-conditions in bromohex-ane at 18 °C, was found to be equal to 0.66. ... 

Similar expansion factors exist for e.g. the ratio of intrinsic viscosities, a. At temperatures just above the 0-temperature, we have the regime of the perturbation treatment. Its extension, the two-parameter theory, relates the expanded chain dimensions to the parameter with P the binary... 

In the study of branching effidmcy of various IMactams in the copotymeri-zatkm with c iolactam, the extoit of branching was diaracterized by the ratio of intrinsic viscosities of branched and linear n)don 6 at the same i e. hyg ... 

An alternate branching ratio, sometimes termed BR, can be determined from the ratio of intrinsic viscosities for a given M... 

The functionalized macrocyclic polystyrenes (110) prepared in cyclohexane exhibited ratios of intrinsic viscosities of the cyclic to the linear polymers of 0.74 and 0.76 for polymers with M =6200 and 4000, respectively, after fractionation [255]. The hydroxyl group functionalities were determined to be 2.0, 1.9, and 2.0 for macrocyclic polystyrenes with M =4000, 6200, and 12,200, respectively [205]. The macrocycle yields were approximately 40%. 

Figure 9.18 Conelation between the melt flow index recoveiy and ratio of intrinsic viscosities of wt% of 95 and SO from the distribution curves. (From Ref. 22.)...

Fig. 4.2. Specific viscosity ratio ( sp,mod/ sp,prec) versus salt concentration for several modified polymers ( ) 3-C18 (A) 3-C14 ( ) 3-C12 (V) 3-C8. Polymer concentration as in Fig. 4.1. (O) and (V) represent the ratio of intrinsic viscosity Mmod/[ ]prec for 3-C12 and 3-C8, respectively...

The intrinsic viscosity depends on the hydrodynamic volume of a molecule and is thus sensitive to the presence of long chain branching, since the presence of branches causes the molecule to occupy a smaller volume than a linear molecule of the same molecular weight. A measure of this effect is the branching parameter g, which is the ratio of intrinsic viscosities of branched and linear polymers having the same molecular weight ... 

Making simplifying assumptions, Stockmayer [60] derived an equation for the ratio of intrinsic viscosities in short-chain branched and linear polymers of the same molecular weight, which is shown below as Eq. 2.105. The assumptions, which are unrealistic for any real material, are that the polymer is monodisperse and that the short branches are equally spaced. 

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