Ratios of Higher Moments

Problem 4.2 A sample of polyfvinyl chloride) is composed according to the following fractional distribution  

This process can be eontinued to obtain other higher averages. The averages commonly used in practice are, however, limited to M , and the viscosity average molecular weight M.  

While Mn, M , and may be obtained by direct measurements (see later), it is usually necessary to measure the detailed distribution of molecular weights to estimate and other averages. Mj, is given by 

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Equation (6.80) gives the identical relation for the mean-field model (with a — 1 /2). Higher-order averages of the distribution are ratios of higher moments with k> 3). These higher-order averages are... 

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