Rate Constants Of Propagation Reactions Research Articles

Copolymerization of N‐vinyl‐2‐pyrrolidone and 2‐phenyl‐1,1‐dicyanoethene

AbstractRadical copolymerization of N‐vinyl‐2‐pyrrolidone (NVP) with 2‐phenyl‐1,1‐dicyanoethene (PDE) was studied in benzene at 70°C. Terminal, penultimate, and monomer complex participation kinetic models were applied to compositional data for best prediction of the copolymer composition. Both penultimate and complex models described satisfactorily the deviation from the terminal copolymerization model, although the complex model did not predict as well as the penultimate model at high NVP/PDE monomer feed ratios. Copolymerization reactivity ratios rNVP = 0.08 and r′NVP = 1.8 indicated substantial effect of the penultimate PDE monomer unit associated with polar repulsion of cyano groups. Equilibrium constant of NVP‐PDE comonomer complex formation was found to be 0.08 L/mol as estimated by proton nuclear magnetic resonance (NMR) analysis of PDE's vinylic proton chemical shift upon complexation. Rate constants of propagation reactions were estimated by applying terminal complex copolymerization model.

Al(Cap)3 as initiator in the anionic polymerization of ε‐caprolactam at high temperature

AbstractMechanism for polymerization of ε‐caprolactam in the presence of both sodium and aluminum caprolactamate was investigated at 171°C. The role of Al(Cap)3 as an initiator was revealed. The apparent rate constant of propagation reaction decreased with the increase in the concentration of Al(Cap)3, as the two different metal salts interact even at 171°C. The activation energy of the overall polymerization reaction with this catalyst system was estimated to be 41.18 kcal/mole.

Rate constant of propagation reaction in stationary state of cationic polymerization. Part VII. Solvent effect

AbstractThe solvent effect on cationic polymerization of styrene derivatives with iodine as the initiator was studied. It was proved that the propagation constant increased remarkably with the polarity of solvent. In the copolymerization the content of the monomer with less solvating power increased in copolymer as the polarity of the medium increased. It was assumed that the process of the dissociation of the gegen anion of the attacking monomer is predominantly rate‐determining in propagation reaction.

Rate constant of propagation reaction in stationary state of cationic polymerization. Part VI.1 Theoretical consideration about the propagation reaction of the cationic polymerization

AbstractThe propagation reaction of the cationic polymerization is considered to proceed by the way of two kinds of ratedetermining steps: The formation of the covalent bond between the polymer cation and the β‐carbon atom of the attacking monomer. The interaction between the ion‐pair (propagating species) and the monomer. Assuming such a tentative reaction scheme, the experimental results on the propagation reaction of the cationic copolymerization reported in part V of this series can be reasonably explained.

Rate constant of propagation reaction in stationary state of cationic polymerization. Part V1. Copolymerization

AbstractIn order to determine the relationship between the relative reactivity of a monomer and that of its propagating species the propagation rate constant of cationic copolymerization was measured. The relative reactivity of the monomer was found in the following order: for styrene derivative p‐methoxystyrene > p‐methylstyrene > styrene > p‐chlorostyrene; for alkyl vinyl ether: isobutyl vinyl ether > 2‐chloroethyl vinyl ether. On the other hand, the order of the relative reactivity of the propagating species ending in the styrene derivative and the alkyl vinyl ether was as follows: for styrene derivative: p‐methoxystyrene > p‐methylstyrene > styrene > p‐chlorostyrene; for alkyl vinyl ether: 2‐chloroethyl vinyl ether > isobutyl vinyl ether.

Rate constant of propagation reaction in stationary state of cationic polymerization. Part IV. Frequency factor (polymerisation of styrene catalyzed by iodine)

AbstractThe pre‐exponential factor (Ap) and the activation energy (ΔEp ≠) of the propagation constant were determined on the cationic polymerization of styrene initiated by iodine in ethylene chloride, the obtained values being about 102l./mole·sec. and 6.5 kcal./mole respectively. The pre‐exponential factor obtained here is much smaller than that of the propagation constant of the radical polymerization. The extraordinarily small Ap value was considered to come from the interaction of the counter anion, and from the statistic consideration experimentally obtained kp value was proved to be reasonable.

Rate constant of propagation reaction in stationary state of cationic polymerization. Part I. A tentative method for determination of rate constant of propagation reaction. (polymerization of p‐methoxystyrene catalyzed by iodine)

AbstractA tentative method for the determination of the rate constant of the propagation reaction (kp) in the stationary state of cationic polymerization was proposed, and as an example of its application, kp values of p‐methoxystyrene initiated by iodine were obtained in ethylene chloride and in carbon tetrachloride. It was found that kp value increased remarkably as the dielectric constant of the polymerizing solution increased. The proprieties of the suppositions upon which the method applied here depended were examined and proved to be reasonable.

Rate constant of propagation reaction in stationary state of cationic polymerization. Part II. Rate constant of the propagation reaction of alkyl vinyl ethers‐iodine systems

AbstractRate constants of the propagation reaction (kp) of isobutyl vinyl ether and 2‐chloroethyl vinyl ether initiated by iodine were obtained in ethylene chloride and in n‐hexane by the method proposed in the proceeding paper. Also in these systems, it was noticed that kp value increased as the dielectric constant of the polymerization system increased. kp values of these two monomers mentioned above were compared with their monomer reactivity ratio and it was proved that the numerical values which we obtained coincided well with each other. Thus, the method of determination of kp applied here must have been reasonable.