CHARACTERIZATION OF MOLECULAR WEIGHT

the molecular weight of a single polymer chain, M, is easily calculated, if the chain length, X, and chemical composition of the repeat unit (and thus the molecular weight of the repeat unit, Mr) are known  

Note that the terms chain length and degree of polymerization can be used interchangeably, and both are represented by x. 

When considering a collection of polymer chains, an average molecular weight must be considered. However, the method for determining this average depends on how you 

Fundamental Principles of Polymeric Materials, Third Edition. Christopher S. Brazel and Stephen L. Rosen. 2012 John Wiley Sons, Inc. Published 2012 by John Wiley Sons, Inc. 

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Table 1. Characterization of Molecular Weights and Intrinsic Viscosities (no Li salts) for End-Capped BPS 40 ...

Characterization of Molecular Weight Distribution and Branching in Polymers... 

Fukushima, M., Tanaka, S., Nakamura, H. and Ito, S. (1996b) Acid-base characterization of molecular weight fractionated humic acid. Talanta, 43, 383-390. 

Characterization of molecular weight distributions by a viscometric method. Nature (Lond.) 183, 1670 (1959). 

Another often used characterization of molecular weight is the viscosity-average molecular weight... 

The methods evaluated for KHI analyses are colorimetric, iodine complexation, and size exclusion chromatography (SEC). The colorimetric method is subject to intense interference by Cl, limiting its application for KHI determination in the presence of Cl blends. The iodine complexation method is chosen as a practical wet chemical method for KHI analysis.lt is modified to minimize the interferences due to brine concentration, corrosion inhibitor, condensate, and sulfide. However, the selectivity of the iodine complexation method is still not at the desired level. As an improvement to selectivity and accuracy, the SEC method is evaluated. The SEC method offers better selectivity and characterization of KHI. The characterization of molecular weight distribution is critical in the evaluation of treatment and removal efficiency of KHI in produced water streams. 

While much of the work done today involves more or less straightforward characterization of molecular weights and molecular weight distributions of... 

Figure 2 HPLC characterization of (A) Hb-bound NO and (B) heme of SNO-PEG-Hb. (A) Samples were separated on a gel-filtration cohimn (8 x 300 mm, GFC-200, Eicom, Kyoto, Japan) eluted with 10 mM acetate buffer, 0.1 mM EDTA, 100 mM sod him chloride, pH 5.5, at the flow rate of 0,55 mlAnin. The eluate was mixed with 1.75 mM mercury chloride at the flow rate of 0.20 mlVmin to decompose S-nitiosylated protein, and further mixed with Griess reagent at the flow rale of 0.22 mlAnin. The red azo-dye formed was determined by the absorption at 540 nm. (B) For the characterization of molecular weight distribution, proteins were sqiarated on a gel-filtration column (7.6 x 300 mm, TSK G3000SW, Toyo Soda Co. IM Tokyo, Japan) in 10 mM sodium phosphate buffer, 100 mM sodium chloride, pH 6.9, at the flow rate of 0.9 mL/min. Proteins were monitored at 420 nm for heme and at 280 nm for molecular weight markers.

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