Averages, of molecular weights

As in the case of particle sizes, averages of molecular weights can also be defined in terms of properties of the dispersions. Here we define one such average based on viscosities of the dispersions. 

The modeling of a polymerization process is usually understood as formulation of a set of mathematical equations or computer code which are able to produce information on the composition of a reacting mixture. The input parameters are reaction paths and reactivities of functional groups (or sites) at monomeric substrates. The information to be modeled may be the averages of molecular weight, mean square radius of gyration, particle scattering factor, moduli of elasticity, etc. Certain features of polymerizations can also be predicted by the models. 

If the polymer is polydisperse, the intrinsic viscosity is obviously related to some kind of average molecular weight, appropriately called the viscosity average by Flory (1943), which depends on the magnitude of o. It is a common practice to define the different averages of molecular weight by the general relationship ... 

M fi Number average of molecular weight at initial time k Kinetic constant... 

Table 8-1. Moments and Averages of Molecular Weights for Some Combinations of s, D, and [rj ...

Fig. 55 Changes in weight average of molecular weight (grey), number average of molecular weight (white) and glass transition temperature (y ( Co)-irradiation dose rate 8.64 kGy.h ). The data were taken from [03T1].

An informative quantity is the static and dynamic scattering function. From this one finds the size, different averages of molecular weight or, in the case of dynamics, the diffusion constant, via the first cumulant. For linear Gaussian chains all these quantities have been calculated extensively, including non-mean field corrections to the size, by renormalization group techniques. ... 

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