Curve copolymerization

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. 

In the following the reversibility of the polymerization of a-methyl-styrene has been taken into account. The copolymerization curves are calculated via Equation 33 together with Equation 34. The equilibrium constants necessary for the calculation are taken from Table II. The depolymerization of methyl methacrylate (I) can be neglected in the temperature range investigated since the equilibrium constants for this monomer (fC2) are extremely small compared with the value for -methyl-styrene—e.g., (21) at 100°C, Ki = 22.9 mole/liter, K2 — 0.12 mole/liter at 80 °C, Ki = 12.9 mole/liter, fC2 = = 0 049 mole/liter. 

Using Equation 37 copolymerization curves can be calculated again. A suitable choice of the copolymerization parameters allows a good fit of the curve to the experimental results. 

The copolymerization parameters for the higher temperatures were calculated from the values at lower temperatures using the Arrhenius equation. The copolymerization curves calculated by Equations 33 and 34 do not agree with the experimental results. 

In the following the reversibility of the polymerization of a-methyl-styrene has been considered. The copolymerization curves were calcu-... 

An equation of the copolymerization curve in the form F, = f(/() has thus been obtained. 

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. 

Neither of the monomers is able to homopolymerize. If a polymeric product is formed, it can only be a strictly alternating copolymer. The copolymerization curve is a horizontal straight line dividing the diagram into two equal rectangles (Fl = 1/2, independent of/,). 

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... 

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 2. NVP/sulfonate monomer copolymerization curves. Key NVP/SPE , NVP/NaSS A, NVP/SPP O, NVP/NaAMPS.

Three different laws were used to assess the reactivity ratios rj of AN (1) and T2 of ATRIF (2) Fineman and Ross method [78], Kelen and Tiidos law [79], and the revised patterns scheme [80]. From the monomer-polymer copolymerization curve, the Fineman-Ross and Kelen-Tiidos laws (Figure 20.2) enabled to assess the reactivity ratios (r = 1-25 0.04 and = 2 = 0-93 0.05 at 70 C)... 

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. 

Examination of a number of the donori-donor2-MA polymerizations by this binary complexomer concept has caused some authors to believe that both the kinetics and polymer compositions showed that the chain-propagation reactions were controlled by the charge-transfer complexes. However, the difference in many cases may not be substantial between the copolymerization curves predicted by a complexomer and free-monomer mechanism, since both mechanisms are only considered approximate treatments." - " ... 

The copolymerization curve of TFE and carboxylated perfluorovinyl ether is shown in Fig. 6. This is a typical behavior of copolymerization of TFE and perfluorovinyl ether. The copolymerization proceeds either in solution or emulsion system with a radical initiator similar to the alternating copolymer systems mentioned above. 

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