Reactivity Ratios and Copolymer Structure

It is obvious, from the wide-ranging values of reactivity ratios shown in Table 5.1, that the structure of the copolymer will also be a function of r and rj. 

Several types of copolymeiic structure can be obtained, as shown in Section 5.1, and the influence of monomer reactivity ratios can be illustrated by examining plots of the instantaneous copolymer composition F against the instantaneous monomer composition in the feed/i, for various combinations of r and rj. 

Consider first the imusual case when r r2 1. This situation arises when httle or no preference for either monomer is shown by the polymer radical, i.e., ki2 

Some Reactivity Ratios r, and f2 for Free Radical Initiated Copolymerizations 

FIGURE 5.1 Variation of with/ for copolymerizations which are I, completely random II, almost ideal (i.e., r r2 = 1.17) III, regular alternating IV, intermediate between alternating and random (i.e., 0 r/2 1) i-e., statistical. 

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