Laser light scattering, molecular weight 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). 

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). 

In addition to refractive index detectors, specialized detectors such as on-line SEC detectors and low angle laser light scattering detectors are used for determining the distribution of molecular weights by SEC. 

---