Molecular weight average, definition

TABLE 1.8 The Most Common Molecular Weight Averages, Their Definitions, and Their Methods of Determination... 

The experimental dependence M = /(V), i.e. the classical SEC calibration curve usually obtained by using narrow standards, in such a case can be obtained directly without calibration from the on-line LS detector. By combining the experimental function M = /(V) and the concentration profile (from DRI), one can construct the complete MMD of the HA sample. The differential and cumulative MMD of a high molar mass HA sample (Mw = 652 kDa, D = 2.1) are shown in Fig. (10). Starting from the initial MMD, the molecular weight averages and dispersity index (Mn, Mw, Mz, and D) could be easily calculated using the appropriate definitions. 

For a precise definition of the molecular weight averages shown in Figure 21.1, see Section 1.5.1. 

Equation (8-5) is valid for monodisperse fractions only. If the fractions are polydisperse, the number-average molecular weight (for definition, see Chapter 1 and Section 8.5.1) must be used instead of the molecular weight Mr. 

Definition of terms relating to individual macromolecules, their assemblies, and dilute solution.This document includes the recommended definitions for molecular weight, molecular weight averages, distribution functions, radius of gyration, end-to-end-distance vector, the Flory-Huggins-Staverman theory, solution viscosity, scattering of radiation by polymers and polymer solutions, fractionation, separation techniques, and so on. The document on dispersity is an important extension of this recommendation. 

Y. Shimoni and D. J. Kouri, Quantum mechanical close coupling approach to molecular collisions Averaged definite parity approximation with Clebsch-Gordan weights, J. Chem. Phys. 66 ... 

Equation (2.39) is the weight average molecular weight as defined in Sec. 1.8. It is important to note that this result. My = M y, applies only in the case of nonentangled chains where 17 is directly proportional to M. A more general definition of My for the case where 17 a is... 

The equation differs from the corresponding one for a copolymer. It is in fact simply an application of the definition of weight average molecular weight [Eq. (10)]. Provided the magnitude of MAB can be established for a mixture of known composition and the molecular weight of one of the polymers is known, Eq. (Ill) can provide the molecular weight of the other polymer if this is unknown. 

This equation can be rearranged to incorporate the definition of the viscosity average molecular weight [2] ... 

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