Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Use was made of differential absorption in the near-infrared region to follow the rates of copolymerization of acrylonitrile (AN, M1) with ethylenesulfonic acid (ESA, M2) in aqueous zinc chloride solution. The concentrations of the monomers were followed separately and simultaneously. It was found experimentally that the ratios d log [M1]/dt and d log [M2]/dt were each constant. This was interpreted to mean that the product of the reactivity ratios of the two monomers (r1,r2) is unity and that the ratio of termination rate constants is equal to the propagation reactivity ratio. It was found that d log [M1]/d log [M2] = r1 = 4.52. This value is in fair agreement with polymer composition data obtained independently. In the Q - e system the equality r1r2 = 1 is equivalent to the monomers having equal e values. Thus, in the AN - ESA system, P1/P2 = k11/k21 = k12/k22 = k1T/k2T, where P1 is the resonance constant of polymer radicals ending in units of M1; and k11, k12, and k1T are the rate constants involving the reaction of this radical with M1, M2, and T (terminating agent), respectively. A gel effect was not observed even at M1 conversions as high as 88%.
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