Copolymer composition cumulative

Mole fraction of styrene in unreacted monomer Cumulative copolymer composition (Equation 5)... 

Bauer et al. describe the use of a noncontact probe coupled by fiber optics to an FT-Raman system to measure the percentage of dry extractibles and styrene monomer in a styrene/butadiene latex emulsion polymerization reaction using PLS models [201]. Elizalde et al. have examined the use of Raman spectroscopy to monitor the emulsion polymerization of n-butyl acrylate with methyl methacrylate under starved, or low monomer [202], and with high soUds-content [203] conditions. In both cases, models could be built to predict multiple properties, including solids content, residual monomer, and cumulative copolymer composition. Another study compared reaction calorimetry and Raman spectroscopy for monitoring n-butyl acrylate/methyl methacrylate and for vinyl acetate/butyl acrylate, under conditions of normal and instantaneous conversion [204], Both techniques performed well for normal conversion conditions and for overall conversion estimate, but Raman spectroscopy was better at estimating free monomer concentration and instantaneous conversion rate. However, the authors also point out that in certain situations, alternative techniques such as calorimetry can be cheaper, faster, and often easier to maintain accurate models for than Raman spectroscopy, hi a subsequent article, Elizalde et al. found that updating calibration models after... 

Similarly, the cumulative copolymer composition, F, is plotted against the conversion, as shown in Figure 7.20, and calculated by a mass balance equation ... 

Fig. 6.19. Experimental results of the on-line controlled emulsion polymerization of S/n-SA (a) cumulative copolymer composition (b) MWD produced at different conversions.

Figure 16 (a) Instantaneous copolymer composition versus comonomer composition with different reactivity ratios and (b) monomer composition, instantaneous copolymer composition, and cumulative copolymer composition as a function of monomer conversion with ri = 0.53, r2 = 0.56, and /i,o = 0.8. 

The instantaneous copolymer composition Fi is related to the monomer composition/i by Mayo-Lewis equation [232], The cumulative copolymer composition Fi is related to not only the monomer composition/i but also the monomer conversion X. The monomer composition/i is further related to the... 

Example 3. For the styrene-butadiene system of Example 1, plot instantaneous copolymer composition Fj and cumulative copolymer composition... 

In this section, the equilibrium of monomer over the different phases is addressed to allow the calculation of the rate of polymerisation, see Equation 4.3 and the instantaneous and cumulative copolymer composition, see Equation 4.2. 

When both monomers are sparsely water soluble, for example, the monomer pairs styrene-butadiene and styrene— -butyl acrylate, the effect of the monomer to water ratio on the monomer composition in the droplet phase as well as in the particle phase is negligible. So for sparsely water-soluble monomer pairs, the monomer to water ratio has hardly any influence on the instantaneous and cumulative copolymer composition. 

The composition of the copolymers produced in batch reactors wiU be dictated by the reactivity ratios of the monomers, r see Equation 4.6, as well as by the mole fractions of the monomers, in the polymer particles, see Equation 4.7. The instantaneous composition can then be predicted by the terminal model, see Equation 4.5. Most of the common monomers employed in emulsion polymerisation recipes present different reactivities, and a consequence of this is the compositional drift (non-constant copolymer composition) produced in batch operation. The compositional drift can be easily calculated by computing the instantaneous, see Equation 4.2, and cumulative copolymer compositions. 

Figure 4.8 clearly shows the evolution of the instantaneous and the cumulative copolymer composition for this comonomer system. The copolymer formed in the initial stages of the polymerisation is rich in MMA the instantaneous composition referred to BA is 0.3. However, when the polymerisation proceeds the more and more BA is incorporated into the copolymer chains. For instance for reaction times longer than 35 min, when overall... 

Figure 4.8 Simulated data for the seeded batch emulsion copolymerisation of MMA and BA, initial molar ratio of BA and MMA is one (a) instantaneous and cumulative copolymer composition (b) ratio of the concentration of monomer in the polymer particles referred to BA, %a = [BA]p/([BA]p + (MMA]p) (c) partial and overall conversions (d) rates of polymerisation.

Figure 4.11 Simulated data for the starved feed semi-batch emulsion copolymerisation of BA and MMA. Initial molar ratio of BA and MMA is one. Instantaneous and cumulative copolymer composition for (a) 3 h and (b) 6 h monomer addition, respectively (c) polymerisation rates (d) CCD for 3 h addition.

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