Mass-average degree of polymerization

NUMBER AND WEIGHT (MASS) AVERAGE DEGREES OF POLYMERIZATION... 

The mass average degree of polymerization, Pw, is defined as the first moment with respect to zero of the differential mass distribution... 

As can be seen from the numerical example (Table 18-4) for a kinetic chain length = 10, the degree of polymerization distribution is exceptionally narrow. Since the mass-average degree of polymerization Xw is obtained from Xw = Xwii, this gives, with Equation (18-45) and X = p I... 

In polydisperse primary chains, therefore, the critical concentration of cross-link-carrying monomer units depends on the mass average degree of polymerization, and not on the number average degree. 

Figure 3.8 Evolution of the number-average and mass-average degrees of polymerization, DP and DP , as a function of conversion in the pregel stage, during the stepwise homopolymerization of an A3 monomer.

Figure 7.3. Variation of the mass average degree of polymerization as a function of the stoichiometric imbaiance ratio (r) for a step-growth polymerization of X- -X + Y- -Y type and various extents of reaction.

---