Laser light scattering distribution

The molecular weight and its distribution have been determined by laser light scattering, employing a new apparatus for ETFE dissolution and solution clarification at high temperature diisobutyl adipate is the solvent at 240°C. The molecular weight of molten ETEE is determined by high temperature rheometry (21). 

In addition to polymer standards, a number of broad distribution, water-soluble polymers can be characterized on TSK-PW columns using universal calibration. These include both fully and partially hydrolyzed PVA, PAAM, PEE, and dextran. PVA, the world s largest-volume, synthetic, water-soluble polymer, was first successfully separated on TSK-PW columns by Hashimota et al. (10). In the 1980s, the use of low-angle, laser light-scattering detection... 

Different methods are available for the determination of the particle-size distribution of powdered solids [30]. These are optical microscopy (usually combined with image analysis), sieve analysis, laser light scattering of suspended particles, and electrical zone sensing. 

The vesicle size is an important parameter not only for in-process control but particularly in quality assurance, because the physical stability of the vesicle dispersion depends on particle size and particle size distribution. An appropriate and particularly quick method is laser light scattering or diffraction. Laser light diffraction can be applied to particles > 1 pm and refers to the proportionality between the intensity of diffraction and the square of the particle diameter according to the diffraction theory of Fraunhofer. 

The observations and questions raised by these workers helped stimulate the experiments which are presented here. In this work, size exclusion chromatography with low angle laser light scattering detection (SEC/LALLS) was used to probe the distribution of branching functionality in multiarm macromolecules of styrene/isoprene and styrene/buta-... 

Light scattering Modem laser light scattering instruments are very advanced devices for particle size distribution analyses. The laser light is scattered by the small dispersed particles or drops. The latter is known to be dependent on the radius of the particle. 

For broader size distributions and dispersions that contain a considerable amount of particles in the upper nanometer and/or the micrometer range, laser light scattering... 

Molecular Weight Distribution from Laser Light Scattering... 

Figure 8. Molecular weight distribution of branched PVAc (B...) as determined by laser light scattering (LLS) and size exclusion chromatography (SEC)/viscometry. A comparison of results by the two methods is listed in Table 2.

Hizukuri, S., Takagi, T. (1984). Estimation of the distribution of molecular weight for amylose by the low-angle laser-light-scattering technique combined with high-performance gel chromatography. Carbohydr. Res., 134, 1-10. 

Yu, L. -P, Rollangs, J. E. (1987). Low-angle laser light scattering-aqueous size exclusion chromatography of polysaccharides molecular weight distribution and polymer branching determination. Journal of Applied Polymer Science, 33, 1909-1921. 

Low Angle Laser Light Scattering (LALLS) results indicate, that at lower DVB/RLi molar ratios, a relatively narrow molecular weight distribution (1.04-1.1) of star-branched polymers can be synthesized. In contrast, DVB/RLi ratios greater than 11 can lead to rather broad molecular weight distributions (Mw/Mn = 1.3). 

Electron microscopy provides direct evidence that the polymerized dispersions still contain spherical liposomes (Fig. 20). Laser light scattering measurements also demonstrate the presence of vesicles in the irradiated dispersions16). The size distribution of vesicles is not significantly altered by polymerization 13) (Fig. 21) as confirmed by gel filtration before and after irradiation of vesicles of (7). 

Recently, Kulicke et al. [145] applied the principle of Flow-Field-Flow-Frac-tionation (F4) in combination with multi angle laser light scattering (MALLS) to characterize PDADMAC. Differential and integral molar mass distributions have been published for PDADMAC. One advantage of this method seems to be that it can be extended to the investigation of the mass distribution of aggregated and particulate components. 

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