Chain-length dependent termination in pulsed-laser polymerization, 3. On the prospects of determining the bimolecular termination constant kt from rate data

✍ Scribed by Oskar Friedrich Olaj; Andreas Kornherr; Gerhard Zifferer

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 613 KB
• Volume: 19
• Category: Article
• ISSN: 1022-1336
• DOI: 10.1002/(sici)1521-3927(19980201)19:2<89::aid-marc89>3.0.co;2-2

✦ Synopsis

The correct (event-weighted) average of k,, (k,), has been calculated from simulation data for pseudostationary laser-induced polymerization for a kinetic scheme with chain-length dependent termination and compared to the average k, which is obtained by employing the formal procedures, originally designed for the evaluation of individual rate constants from rate data in the case of chain-length independent termination. Satisfactory (and in fact excellent) results are obtained only if the complete equation for the conversion per laser pulse is solved for it. This leads to an almost perfect recovery of the power-law governing the dependence of k, on chain-length, especially the exponent.

Rate data as well as degrees of polymerization from stationary free radical polymerizations always yield the rate constant of propagation kp and the rate constant of bimolecular termination in a fixed combination (k;/k,) to some power n. Since decades it has been a challenge for kineticists to resolve this ratio into its individual components kp and k,. For years the usual way was to resort to nonsta-