Styrene copolymers composition curve

Variation of Styrene Content with Extent of Conversion. Figure 8 gives the relationship between copolymer composition and the extent of conversion for copolymers of butadiene and styrene (25 wt.7. styrene) prepared in toluene, at 30°C, with n-BuLi and barium salts of t-butanol and water. For comparison purposes, the copolymer composition curve is shown for the reaction initiated using n-BuLi alone. Copolymerization using n-BuLi results in very little incorporation of styrene into the copolymer chain until about 757. conversion, after which the styrene content increases very rapidly. In contrast, copolymerization using the barium salts and n-BuLi results in an increased incorporation of styrene at the same extents of conversion. 

Fig. 1. Copolymer composition curves for the copolymerization of methyl a-methoxyacrylate and styrene by AIBN in the presence (o) and absence ( ) of ZnCl2 at 60 °C and the polymerization rate in the presence of ZnCl2 (a).

Some data recently obtained on high pressure ethylene copolymerizations illustrate the quantitative aspects of an ethylene-based Q-e scheme (6). In Figures 3 and 4 copolymer composition curves for the ethylene-vinyl chloride and the ethylene-vinyl acetate copolymerizations are given. The monomer reactivity ratios for these two systems are tabulated in Table III along with Q values and e values for vinyl chloride and vinyl acetate calculated using ethylene as the standard (Q = 1.0 and g = 0). These Q and e values may be compared with those obtained using styrene as the standard. 

Equally important, the two comonomers were polymerized in parallel, with MMA consumption slightly faster, and the copolymer composition curve shows a shallow S-shaped profile, similar but not identical to those for the textbook examples of free radical MMA/styrene copolymerization. Thus, once again, the observation is consistent with some radical growth in the metal catalysis, and their difference from a conventional radical copolymerization is not deniable but not conclusive. 

Figure 3. Copolymer composition curve for styrene-acrylonitrile...

Example 10.1 Discuss the Monomer-Copolymer Composition Curve for the System Methacrylonitrile-Styrene Formed in a CSTR... 

Let the monomer 1 be methacrylonitrile (MAN) and monomer 2 be styrene (STY). It can be seen from Table 10.1 that the reactivity ratios 2 and r2i are equal to each other and are 0.25. The monomer and copolymer composition curve is shown in Figure 10.4. 

It can be seen from Figure 10.4 that the copolymer composition curve is 5 shaped or sigmoidal. Below the azeotropic composition, MAN is favored into the polymer and is more selective. Above the azeotropic composition of 0.5 mole%, the styrene is more selectively added into the copolymer chain. 

Calculate the copolymer composition curve for alphamethyl-styrene and maleic anhydride. The reactivity ratios are r,2 = 0.14 and r2i = 0 03-... 

Figure 8 Copolymer composition curves for radical copolymerization of PMMA macromonomer(M and styrene with AIBN in toluene at 60°C.

Figure 3 Copolymer composition curve for bulk polymerization of styrene and acrylonitrile at 60 C. Ya = mole fraction AN in the polymer Xa = mole fraction AN in the monomer experimental data o terminal model-----, penultimate model ----. ...

Figure 7 Copolymer composition curves for copolymerization of styrene and acrylonitrile at 60 C. Acetonitrile 4- i toluene Q bulk----...

Figure 12. Composition curves of the copolymers of MMA and styrene by the copolymerization initiated with starch on standing (starch 0.1 g, CuCh 2HtO 0.5 mg, HsO 10 cm3, (MMA styrene) 3 cm 85°C,3hr)...

Figure 26 compares the conversion as a function of time in concentrated emulsion and bulk polymerization and shows that polymerization proceeds much faster in a concentrated emulsion. The concentrated emulsion has an internal phase ratio of 0.93 and a molar ratio of MAA/styrene of 0.036. The molecular weight distributions of the polymers generated by both processes are presented in Fig. 27, which shows that concentrated emulsion polymerization leads to molecular weights an order of magnitude higher. Since the copolymer composition changes with conversion, the GPC curves were recorded at the same conversion. 

Fig. 7-1. Relation between instantaneous feed composition f and corresponding copolymer composition F for random copolymerizations. Curve I. ethylene (ri = l)-vinyl acetate (ri = I) curve 2, styrene (rj = 0.8)-butadiene (rz = 1.4) curve 3, vinyl chloride (/ = l.4)-vinyl acetate O z = 0.6.S) curve 4, vinylidene chloride (r = 3.2)-vinyl ehloride (12 = 0.3).

Figure 11. Copolymer composition (Plv), average styrene sequence length (Ns) and number average molecular weight as function of the retention volume. Molar feed composition is 0.90. PS is the polystyrene calibration curve. Key , Mn A>...

The styrene-based random copolymers R-12 and R-13 were prepared by ruthenium and copper catalysts, respectively. For the former copolymer (R-12), the copolymerizations were investigated with various compositions of the two monomers, which revealed that the composition curve is similar to that of conventional radical copolymerizations.205 The latter copolymers (R-13) obtained with R—Br/CuBr have... 

Figure 1. Monomer—copolymer composition relationship for the plasma-initiated copolymerization of methyl methacrylate with styrene. Plasma-initiated polymerization (%) NMR, (x) elemental analysis. Thermal polymerization (O) NMR, (Aj elemental analysis, (—) theoretical curve, tmma = 0.46 =...

To determine the SAN copolymer composition, the same procedure used for styrene/isoprene was followed. A series of reactions was performed varying the feed of acrylonitrile and measuring the incorporation of acrylonitrile in the copolymer at low conversion by NMR spectroscopy. All reactions were done in a closed pressure reactor at 115-120 C. The results of these experiments are shown in Table IV. A plot of the incorporation of acrylonitrile in the polymer (Fa) as a function of the acrylonitrile feed (fA) is shown in Figure 5. The data points are copolymer compositions for the SFR process while the curve represents literature data for a... 

Figure 18.4 Effect of particle morphology on MFT (a) curves of polymer compositions in different morphology particles vs MFTs of onulsions for the MMA-BA system ( ) I BA/n MMA, ( ) blend, ( ) copolymer (b) curves of polymer compositions in gradient latex particles vs MFTs of emulsions for the A4MA-BA system ( ) from internally soft to externally hard, (A) from internally hard to externally soft, ( ) homogeneous copolymer latexes (c) curves of polymer compositions in different morphology particles vs MFTs of emulsions for the styrene-EA system ( ) blend, ( ) copolymer, (V) I EA/n styrene, (O) I styrene/n EA. (Reproduced with permission from Cao et al. f561.1...

In our own laboratories, Dr. Masao Murano [52] has used Mochel s methods to study the aromatic proton resonance patterns obtained with styrene-MMA copolymers. Spectra recorded with a 100 MHz spectrometer revealed separate resonances for the o- and (m + p)-aromatic protons of isolated styrene units. Six curves were therefore used to reproduce each observed aromatic proton resonance pattern gaussian curves were used to represent the resonance of o-aromatic protons lorentzian curves were used to represent the resonance of (m + p)-aromatic protons. The o- and (m + p)-resonance areas corresponding to protons in each type of styrene centered triad were maintained in a 2 3 ratio. It proved possible to obtain an excellent fit of observed aromatic resonance patterns to calculated triad distributions for copolymers of all compositions. Fig. 14 shows how the aromatic proton resonance pattern for one copolymer could be matched by summing o- and (m + p)-curves representing the various possible... 

Assuming the copolymerization data showed the NVPI (Mi) copolymerized with charge-transfer complexes of the two other donor-MA (M2) pairs, modified reactivity ratios were determined for the two systems.The reactivity ratios for the NVPI (Mi)-M2 (BVE-MA) and M1-M2 (a-methyl-styrene-MA), respectively, were ri = 0.16 and r2 = 1.09 and ri = 0.30 and / 2 = 1.70. A copolymerization curve with these modified reactivity ratios more adequately described the observed copolymer compositions than the classical concept. 

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