Intrinsic viscosity distribution

Synthetic, nonionic polymers generally elute with little or no adsorption on TSK-PW columns. Characterization of these polymers has been demonstrated successfully using four types of on-line detectors. These include differential refractive index (DRI), differential viscometry (DV), FALLS, and MALLS detection (4-8). Absolute molecular weight, root mean square (RMS) radius of gyration, conformational coefficients, and intrinsic viscosity distributions have... 

SEC-VIS Intrinsic viscosity distribution Molar mass distribution... 

SEC-VIS-LS Intrinsic viscosity distribution Radius of gyration distribution Copolymer Mn Copolymer Mn... 

Intrinsic viscosity distribution Directly from experiment, not affected by non-exclusion effects... 

A viscometric detector together with a concentration detector can provide information on molar masses of macromolecules emerging from the FFF system [76,134,142-144] using the Mark-Houwink-Kuhn-Sakurada coefficients. If these coefficients are not available, an intrinsic viscosity distribution can still be determined without calibration. Detailed features of this distribution are unique to a given polymer sample, and are not affected by changes in experimental conditions [145]. In fact, since the intrinsic viscosity distribution is more directly related to end-use properties, its measurement is preferred in certain applications. 

If a concentration-selective detector, such as a DRI, is connected on-line with the viscosity detector, the ratio of the two signals yields the intrinsic viscosity distribution of the polymer sample. In polymer characterization, the intrinsic viscosity can be a property just as important as the molecular-weight distribution. Furthermore, polymer intrinsic viscosity follows the Mark-Houwink relation to the molecular weight, M, where K and a are Mark-Houwink viscosity constants ... 

The intrinsic viscosity is a fundamental property of the polymer sample in solution, and thus the intrinsic viscosity distribution (IVD) (C versus log[T7j) with associ-... 

With the intrinsic viscosity distributions obtained from either a viscometer or light scattering detector, previous studies have attempted to quantitatively determine the amount of long-chain branching. First, g was related to g using an assumed value of s, and the appropriate equation from Table 1 was used to calculate the number of branches per molecule. However, because of the assumptions involved, it is more... 

Another approach to the SEC-viscometry data is that of Kirkland et al. (20). The intrinsic viscosity is a fundament property of the polymer sample in solution, and thus polymers may be characterized in terms of their intrinsic viscosity distribution (IVD) without attempting to convert this into a molecular weight distribution. Moments of the IVD may be calculated similar to those for the MWD (21). The advantage is that the intrinsic viscosity distribution is di-... 

The significance of knowing the K and a values is that molecular weight distribution data can be directly calculated using one of two methodologies (1) the Mark-Houwink method, which requires prior knowledge of K and a values for PVA and the calibration standards, such as PEG and PEO, and (2) the intrinsic viscosity distribution (IVD) method as reported by Yau and Rementer... 

Hence it is possible to construct an intrinsic viscosity distribution curve. The weight average intrinsic viscosity calculated from the IV distribution curve is the same as that obtained for a polymer by dilution viscometry ... 

Since the intrinsic viscosity measurements have been the cornerstone of industrial characterization measurements, it is expected that the measurement of this parameter and the other associated measurements, such as intrinsic viscosity distribution by GPC, will become more important from a quality control standpoint than the traditional measurement of molecular weight distribution, which has not previously been related to intrinsic viscosity. Of particular importance for quality control are the claims made for the technique, namely that IVD measurement is much less sensitive to column deterioration, flow rate variations and column loading. 

The intrinsic viscosity is a fundamental property of the polymer sample in solution, and thus the intrinsic viscosity distribution (TVD) (C vs. log[77]) with associated statistical moments may be used to characterize polymers without converting this distribution into a MWD. The FVD can be determined in GPC-viscometry directly, without resorting to universal calibration. This distribution depends not only on the polymer sample itself but also on the solvent and the temperature, and hence does not possess the versatihty of the MWD. Nevertheless, the IVD measurement in GPC-viscometry is much less sensitive to experimental conditions than any cahbration curve and, hence, can be successfully used in industry (e.g., for quality control of polymers in production). 

In any other case it has to be assumed that the unknown sample has a different distribution function of the molar mass and therefore a different distribution function of the intrinsic viscosities of each fraction of the sample. According to Philippoff [72], it could be shown that the measured intrinsic viscosity is a mass average (see Chap. 2) of the intrinsic viscosity distribution ... 

On-line viscometers allow measurement of an intrinsic viscosity distribution (IVD) and in combination with light scattering the two techniques provide a powerful array of tools to investigate structural characteristics and molar mass averages. 

MMD molar mass distribution, IVD intrinsic viscosity distribution, RGD radius of gyration ... 

With multidetector GPC, it is possible not only to obtain absolute MWD combining static light scattering with concentration detection, but also to have the radius of gyration and intrinsic viscosity distributions. 

MMD, molar mass distribution IVD, intrinsic viscosity distribution RGD, radius ot gyration distribution. 

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