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Requirements Associated with Studies into a Chain-Length Dependence of Propagation Rate Coefficients via PLP−SEC Experiments
- Source :
- Macromolecules; December 2002, Vol. 35 Issue: 25 p9300-9305, 6p
- Publication Year :
- 2002
-
Abstract
- Experiments directed toward the determination of free-radical propagation rate coefficients k<INF>p</INF> from pulsed laser initiated polymerizations (PLP) in conjunction with size-exclusion chromatography (SEC) were modeled using the program PREDICI. The simulations were carried out in order to investigate whether an experimentally observed variation of k<INF>p</INF> with the initiating laser pulse repetition rate is necessarily due to a chain-length dependence of k<INF>p</INF>. The modeling was performed for laser pulse repetition rates ranging from 0.5 to 50 Hz and primary radical concentrations being varied by more than 2 orders of magnitude. The resulting molecular weight distributions were very different in shape. The k<INF>p</INF> data derived from the simulated molecular weight distributions showed a variation of about 30% with chain lengths, although the same propagation rate coefficient was introduced into all the simulations. The experimental finding of k<INF>p</INF> being dependent on chain length induced by using different laser pulse repetition rates is not necessarily due to a chain-length dependence of k<INF>p</INF>. The modeling results show the importance of reporting all experimental details together with k<INF>p</INF> data derived from PLP−SEC experiments.
Details
- Language :
- English
- ISSN :
- 00249297 and 15205835
- Volume :
- 35
- Issue :
- 25
- Database :
- Supplemental Index
- Journal :
- Macromolecules
- Publication Type :
- Periodical
- Accession number :
- ejs3979347
- Full Text :
- https://doi.org/10.1021/ma020437m