Average molecular weights cumulative

Figure 1 Is a flow sheet showing some significant aspects of the Iterative analysis. The first step In the program Is to Input data for about 50 physical, chemical and kinetic properties of the reactants. Each loop of this analysis Is conducted at a specified solution temperature T K. Some of the variables computed In each loop are the monomer conversion, polymer concentration, monomer and polymer volume fractions, effective polymer molecular weight, cumulative number average molecular weight, cumulative weight average molecular weight, solution viscosity, polymerization rate, ratio of polymerization rates between the current and previous steps, the total pressure and the partial pressures of the monomer, the solvent, and the nitrogen.

It should he understood that the weight average molecular weights appearing in equation (IT) are cumulative ones. 

Figure 9. Change in cumulative and instantaneous weight average molecular weights...

Fig. 23. Cumulative weight loss ( ) and cumulative release of 5-fluorouraeil (5FU) ( ) from polymer disks prepared from 3,9-bis (ethylidene-2,4,8,10-tetraoxaspiro [5,5] undecane) and 1,6-hexanediol at pH 7.4 and 37 °C. Devices contain 10 wt% 5FU and 0.15 wt% suberic acid. Numbers indicate weight average molecular weight of residual polymer [42], Reprinted with permission...

The cumulative number (Mn) and weight (M ) average molecular weights can be calculated from the moments of the MWD as follows ... 

FIGURE 12.15 The effect of an initiator boost during BA free radical polymerization on both the cumulative and the instantaneous weight-average molecular weight, from ACOMP, illustrated in the rapid change in slope at the moment the initiator is added (top). 

The cumulative weight average molecular weight, M (0, can be conveniently calculated using the mass of polymer in the... 

Under isoreactive conditions, the cumulative weight average molecular weight equals the instantaneous weight average molecular weight, which can be predicted by ... 

The average molecular weight of the long chain and short chain is 41,000 and 2500, respectively. When the short chain concentration changed from 20 to 80 wt%, gel concentration increased. The broken line near the solid line is the cooperative diffusion constant obtained by the cumulant method... 

Figure 7 shows the cumulative chromatograms of the polymer samples collected at different conversions from the bulk MMA polymerization initiated with 0.5% AIBN at 70 °C, as well as their average molecular weights. Theoretically, the instantaneous molecular weights can be obtained from derivatives of the cumulative data. However, the accuracy can be an issue in this praaice. 

Due to the nature of random termination and/or transfer reactions, the instantaneous polymer has Flory s most probable MWD with polydispersity equal to 2. The cumulative average molecular weights can be found from their integrations with conversion, MN,cum = V(io / N) and Mw,cum = (Jo w dx)/. Figure 14 shows the development of monomer conversion and polymer particle size in the emulsion polymerization of styrene. 

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