Copolymerization diagram

The dependence of the composition of the copolymer on the proportions of the monomers in the initial mixture can be portrayed graphically in a so-called copolymerization diagram (Fig. 3.4). The mole fraction of one of the two monomeric units in the resulting copolymer is plotted against the mole fraction of this monomer in the original reaction mixture the curve can also be calculated from the reactivity ratios by means of Eq. 3.18. 

In such cases the polymerization can be taken to relatively high conversion without change in composition of the copolymer formed (see Example 3-37). In the copolymerization diagram the azeotrope corresponds to the intersection point of the copolymerization curve with the diagonal. For example, from Fig. 3.4 it may be seen that in the radical copolymerization of styrene and methyl methacrylate the azeotropic composition corresponds to 53 mol% of styrene. 

The chlorine content of the dried copolymers can be determined gravimetrically according to the method of Wurtzschmitt, and their composition derived.The copolymerization diagram is drawn and the reactivity ratios are calculated. 

Fig. 10. Copolymerization diagrams for ethylene/propylene copolymerization carried out with (Me2C(3-tert-BuCp)(Flu))ZrCl2 at 30 ( ) and 60°C ( ). (120).

Equation (70) itself is, of course, no more illustrative than eqn. (66) but its graphical representation provides a clearer picture of the dependence of copolymer composition on the momentary relative contents of the two monomers in the mixture. The copolymerization diagram, as the F, = fft) dependence is called, also clearly illustrates the role of the copolymerization parameters in copropagation (see Fig. 17). 

In this case, copolymerization is ideal the relative contents of the two monomers in the monomer mixture and in the product are identical. The copolymerization curve forms a diagonal in the square copolymerization diagram. 

From the copolymerization equation, a situation can easily be derived where the compositions of the monomer mixture and the generated polymer will be equal (F, = fx) and the copolymerization curve will intersect the diagonal of the square copolymerization diagram. This will occur, apart from the case of eqn. (71) when r,[Mj] + [M2])/(r2[M2] + [Mj]) = 1, i. e. when... 

Figure 7.1 Copolymerization diagrams (without inflection points) showing instantaneous composition of copolymer (mole fraction Fi) as a function of monomer composition (mole fraction /i) for copolymers with the values of Vi = l/i"2 for ideal copolymerization.

Figure 7.2 Copolymerization diagrams with inflection points showing composition of copolymer Fi as a function of monomer composition /i for the values of the reactivity ratios ri/r2 indicated.

What values of ri and T2 would yield copolymerization diagrams F vs. /i) (a) without inflection points, (b) with inflection points ... 

Fig. 32. C oiisii uction of the (f j — /,) curve from the (S - AN) copolymerization diagram.

Figure 3. Copolymerization diagram of the system vinylene carbonate/ vinylidene chloride at 65°C...

Reactivity Ratio Studies. DHA-4VP System. A series of DHA-4VP (MrM2) copolymerizations was carried out to low conversions (<10% ) with the monomer pair ratio being varied. Table III summarizes the data. In the corresponding copolymerization diagram, the composition of the copolymer is plotted as a function of the composition of the initial monomer concentration... 

The copolymerization diagrams plotted for the mixtures with the molar ratios of p- and m-DVB ranging from 2 1 to 1 4 show that when the p-DVB content in the initial monomer mixture increases, the nonuniformity in crosslinks distribution in the resulting network is also increased (Fig. 1.2). 

If one wishes to attain high conversion at constant composition, the more reactive monomer must be added in a programmed manner. The procedure is as follows from the copolymerization diagram (or from the reactivity ratios) one obtains the monomer composition that will lead, at low conversion, to the desired copolymer composition. A conversion/time curve is drawn up for this system and the composition of the copolymer determined from time to time. From this, one can find how much of the more reactive monomer is to be added at given times during the polymerization in order to maintain an approximately constant composition (see Example 3.39). Special computer software has already been developed for this. 

From the copolymerization Eq. 3.18 and the copolymerization diagram (Fig. 3.4) some special cases can be derived (see Table 3.10). When the compositions of the... 

The copolymerization parameters r for MMA/sfMA-H2F8 (obtained by inline-NMR monitoring), and for MMA/sfMA-HlFl in dimethyl acetamide (DMAc) resulting from the copolymerization diagram at low conversions [104] are summarized in Table 11.1. 

Table I lists monomer feed compositions, copolymer compositions and conversions obtained in the copolymerization experiments. The copolymerization diagram of the system (Fig. 4) shows a tendency towards alternation with an azeotropic point at 70 mole % MA. Reactivity ratios for the aFS-MA copolymerization system, determined by the Kelen-Tudos method were r =0.26 and The KT-plot is shown in Figure 5. Average monomer feed compositions were used for this determination whenever the conversion was above 10 wt. percent. Almost identical values of the reactivity ratios were obtained when calculated by the Tidwell-Mortimer method. The reactivity ratio product for this copolymerization system ( MA aFS" 2) indicates a tendency for alternation.

The result of the quantitative evaluation of the growth of the copolymer brushes of styrene and methylmethacrylate is depicted in the copolymerization diagram in Fig. 23. For MMA = Mi and styrene = M2 the resulting copolymerization parameters were determined to be ri = 0.29 and r2 = 0.70. The values are in good agreement with the parameters reported for free radical copolymerization of MMA and styrene in solution [57]. 

Figure 23 Copolymerization diagram for the copolymerization of MMA and styrene by grafting-from polymerization using immobilized azo initiators as obtained from FTIR spectroscopy (full circles) and XPS (open circles). The sobd line gives the theoretical curve as calculated from the copolymerization equation, Eq. (5).

Figure 18 Copolymerization diagram for co(ethene-Un-OH) with different metallocenes. Reproduced from Ahjopalo, L. Lofgren, B. Hakala, K. etal. Eur. Polym. J. 1999, 35,1519. ...

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