Polymerization weight-average chain length

Solution The number and weight average chain lengths for a self-condensing polymerization are obtained from Equation (13.18) and (13.19) by setting Sab= E ... 

Fig. 21 Calculated development of the weight-average chain length during the model emulsion polymerization...

Figure 15.10 Effect of the operating pressure, P, on (a) polymerization rate, (b) number- and weight-average chain lengths, (c) gel fraction, and (d) crosslink density. Source Reprinted with permission from Quintero-Ortega lA, Vivaldo-Lima E, Luna-B cenas G, Alvarado JEJ, Louvier-Hernandez JF, Sanchez IC. Ind Eng Chem Res 2005 44 2823 [44]. Copyright 2005 American Chemical Society.

Table 2.7 shows the maximum molecular weights of polybutadiene attainable at different polymerization temperatures, prior to gelation, expressed as the critical weight-average chain length, x, of the primary chains at the gel point. 

Figure 8 Increase of weight-average chain length with monomer conversion during the bulk polymerization of vinyl acetate at 60 °C. ...

Equations [254] clearly shows that the polymerization system reaches the gel point when each primary chain has one cross-link point by its weight average, that is, pfwp = This conclusion is always tme regardless of the type of primary chain distributions since no primary distribution is assumed in the equation derivation. At the gel point, the weight-average chain length approaches a theoretical infinity and gel molecules start to form. The gel fraction, that is, the ratio of the number of monomeric units in gels to that of total monomeric units, can be predicted by Flor/s recursive equation ... 

FIGURE 9.6 Instantaneous and cumulative number- and weight-average chain lengths and the cumulative polydispersity index for an isothermal, free-radical, batch polymerization (Example 9.12). 

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