Mechanism of isomerization of nascent molecular Cis polyacetylene in course of Ziegler-Natta polymerization of acetylene
| Autor: | Marc J. M. Abadie, Vlado Tabacik |
|---|---|
| Rok vydání: | 1989 |
| Předmět: |
biology
Mechanical Engineering Metals and Alloys Activation energy Natta Condensed Matter Physics First order biology.organism_classification Photochemistry Electronic Optical and Magnetic Materials Catalysis Polyacetylene chemistry.chemical_compound chemistry Acetylene Polymerization Mechanics of Materials Materials Chemistry Physical chemistry Isomerization |
| Zdroj: | Synthetic Metals. 28:D721-D726 |
| ISSN: | 0379-6779 |
| Popis: | We have studied the cis/trans isomeric compositions relative to two series of pristine polyacetylene films synthetized at different temperatures (−78°C to 150°C, with (Al/Ti) = Const) and at different (Al/Ti)-ratios (1 t0 4, with T = Const). It is shown, that isomeric compositions result from a first order chemical process with Aτ = 37 ± 9 and with a surprisingly small activation energy E a = (2.3 ± 0.5) kcal/molePA. This is about ten to twenty times less than E a s characterizing the thermal isomerisation of PA Cis contained in PA free standing films. A model is proposed of a first order chemical process based on the presence in the Z-N medium of an equilibrium of two active species of catalyst. Such equilibrium is both temperature and (Al/Ti) controled. |
| Databáze: | OpenAIRE |
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