Über den Mechanismus von Polymerisationsreaktionen. I.

Polmerization

“…Such mechanisms have been treated by Chalmers, by Dostal and Mark (12), by Dostal (10), by Gee (25) who speaks of activated molecules rather than free radicals, by Gee and Rideal (26) who appear to assume thermal rather than material chains, by Schulz (51) who speaks of activated molecules instead of free radicals, by Flory (21), by Dostal, Mark, and Raff (13), Mark (37), Schulz and Husemann (52), Semenov (54), Mark and Raff (38), and Bawn (2).…”

“…Xmer-catalyst complex + monomer -> (X + l)mer-eatalyst complex or -Xmer--fmonomer -> -(X + l)merhave not been determined directly since more than one reaction is involved. The energy of activation for the possible bimolecular formation of free radicals was estimated to be from about 20,000 to 40,000 calories per mole (12), and that for the chain growth step from < 5,000 to 15,000 calories (12,20,88). The temperature-independent factors are known to be small for the initial step in the case of butadiene (29), and the relative factors for chain initiation and chain growth have been estimated by Mark and Raff on the basis of the theory of Dostal and Mark.…”

Mechanism of Thermal Polymerization and Polycondensation

“…Even when there is no deactivation reaction (that is, when the reaction chains are not broken by special chemical processes), a definite chain-length distribution occurs, when a given amount of the monomer undergoes polymerization (6). .…”

“…for chains of equal age. In the case that the rate of deactivation is so great that the chains are active only during a relatively short time, and the deactivation is caused only This formula holds, of course, only if b is so large that So becomes small in comparison to 1; otherwise the equation proposed in formula 6 would not be right. If we have, from experimental values, a plot of S as a function of time, we can find the value So; then we have a relation between a and b.…”

Graphical method for polymerization kinetics. 3. Living polymerization with nonequal propagation rate constants

“…Terminationless polymerization was first described by Ziegler1-3 and later by Mark. 4 For living polymerization with the initiation rate constant equal to the propagation constant, Flory5 has given the Poisson distribution for the polymer formed. However, it was Szwarc6,7 who actually discovered living polymerization in 1956 on the basis of highly convincing experiments.…”