Molecular mass, determination weight average

In order to remove the residual solvent from PHB films, the samples were kept for 2-3 h in vacuum at 80 °C. The completeness of solvent removal was checked by monitoring a decrease in intensity of the corresponding absorption bands of dioxane (873-876, and 2855 cm ) and chloroform (756, 3012-3040,2976-2992 cm ) in the IR spectra [12]. The degree of polymer crystallinity in the samples of both types was about 70%, as evidenced by the X-ray diffraction data [7, 8]. The weight-average molecular mass determined by viscosimetry was (310 26) 10 ... 

A measure of the breadth of the molecular mass distribution is given by the ratios of molecular mass averages. The most commonly used ratio Mw/Mn — H, is called the polydispersity index. Wiegand and Kohler discuss the determination of molecular masses (weights) and their distributions in Chapter 6. 

In principle, MALDI-TOF (MALDI-Time Of Flight) analysis allows for the determination of the complete polymer mass distributions and, from that, the calculation of various molecular weight averages like Mn and Mw and the... 

Mass ratios are determined by using the molecular masses (also called molecular weights) of the substances involved in a reaction. Just as the atomic mass of an element is the average mass of the element s atoms, the molecular mass of a substance is the average mass of the substance s molecules. Numerically, molecular mass (or more generally formula mass) equals the sum of the atomic masses of all atoms in the molecule. 

Consideration was given to multibranching processes finite aggregation distribution (a sol), infinite aggregate (a gel) existence criteria, and relations for the determination of mole- and weight-average molecular masses of the finite aggregates. 

Molecular weight distribution of isolated samples. Mn is number-average molecular mass. cNot determined. 

Determine the average molecular weight of a mixture fi-om the mass or molar composition of the mixture. 

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