High-Temperature Propagation and Termination Kinetics of Styrene to High Conversion Investigated by Electron Paramagnetic Resonance Spectroscopy

Autor:	Per B. Zetterlund, Bunichiro Yamada, Satoru Yamauchi
Rok vydání:	2004
Předmět:	Polymers and Plastics Bulk polymerization Chemistry Diffusion Organic Chemistry Radical polymerization Degree of polymerization Condensed Matter Physics Reaction rate constant Polymerization Polymer chemistry Materials Chemistry Physical and Theoretical Chemistry Spectroscopy Glass transition
Zdroj:	Macromolecular Chemistry and Physics. 205:778-785
ISSN:	1521-3935 1022-1352
DOI:	10.1002/macp.200300148
Popis:	The free radical bulk polymerization of styrene at 120°C has been investigated over almost the entire conversion range using electron paramagnetic resonance spectroscopy, Fourier-tranform near-infrared spectroscopy and gel permeation chromatography. The free radical concentration went through a sharp maximum that coincided with the peak in the rate of polymerization during the gel effect, and shifted to higher conversion with increasing initiator concentration. The termination rate coefficient(κ t ), decoupled from the initiator efficiency(f) by use of the instantaneous degree of polymerization, remained close to constant up to as high as approximately 80% conversion, at which a dramatic decrease occurred. Both the propagation rate coefficient (κ p ) and f fell ordes of magnitude near 80% conversion in spite of the temperature being above the glass transition temperature of the system. The value of κ p increased with the initiator concentration at a given conversion in the highest( diffusion-controlled) conversion range.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::aab2bffc7aa1010c5a3ad9513313a154 https://doi.org/10.1002/macp.200300148 Zobrazit plný text záznamu Plný text