On some kinetic aspects of solid-state polymerization
| Autor: | I. M. Papissov, V. A. Kabanov |
|---|---|
| Rok vydání: | 1967 |
| Předmět: |
Quenching
Kinetic chain length chemistry.chemical_classification Quantitative Biology::Biomolecules Materials science Nucleation Polymer Quantitative Biology::Subcellular Processes Condensed Matter::Soft Condensed Matter Crystal chemistry.chemical_compound Crystallography Monomer chemistry Polymerization Chemical physics Macromolecule |
| Zdroj: | Journal of Polymer Science Part C: Polymer Symposia. 16:911-919 |
| ISSN: | 0449-2994 |
| Popis: | Solid-state polymerization is considered as an irreversible phase transition of monomer erystals into polymer. The theoretical relationship between critical size of the polymer nucleus in a monomer crystal and single macromolecule dimensions is obtained on the assumption that the polymer nucleus formed by closely packed extended macromolecules has a cylindrical shape. By using this relationship it is shown that in some cases the growing of a single chain in a monomer crystal could be thermodynamically unfavorable. In such cases one should expect the propagation of bundles of macromolecules. Processes of this kind are characterized by a slow nucleation rate and autocatalytic acceleration at the polymer-monomer interphase. At the same time it is supposed that in the course of irradiation of single macromolecules could instantly grow in some “hot” regions of a monomer crystal. If the “critical” nucleus has to contain more than one macromolecule, the “cooling off” of these regions should be followed with quenching of thermodynamically unstable single polymer chains, which then could be depolymerized under irradiation or annealed. This consideration is used to explain some cases of low limit conversions into polymer observed for a number of crystalline monomers. |
| Databáze: | OpenAIRE |
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