Vinyl type polymers can form thermoreversible gels, precipitates and solution crystals in dilute to moderately dilute concentrations of suitable solvents. Although the thermoreversible gelation of the vinyl polymers has been extensively studied, no unifying principles have as yet emerged that establishes the underlying mechanism(s). In the present work an attempt has been made to develop the general underlying aspect of this problem by studying the gelation behaviour of a complete set of stereostructure of the vinyl polymer, in selected solvents using polystyrene as a model system. / Underlying this research has been the determination for each polymer-solvent pair, of the kinetics, pseudo phase diagrams, and thermodynamic properties of the gelation as well as that of the related precipitates and crystallites that are formed. The kinetic studies served as a guide for establishing the appropriate conditions for the study of gelation mechanism and the thermodynamic structural properties of the gels and other species that are formed. The results obtained showed that the mechanisms of the gel formation depends on the specific solvent used. Five different gelation mechanisms were identified, depending on the situation. One or several of these mechanisms could be operative with the same polymer-solvent system. It has been established where and why these mechanisms are operative in terms of the kinetics of the processes involved, the position of the binodial and the chain structure. / For those polymers that form gels by a crystallization mechanism, a polymorphic crystalline structure is observed quite often. An extensive study regarding the conditions for the emergence, the crystallographic structure and the stability of the polymorphic structure was performed. The reason for the polymorphism can now be shown to be a natural consequence of the crystallization kinetics and is not a requirement for the gel formation as has been hypothesized. / Source: Dissertation Abstracts International, Volume: 51-01, Section: B, page: 0230. / Major Professor: Leo Mandelkern. / Thesis (Ph.D.)--The Florida State University, 1989.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_78153 |
| Contributors | Prasad, Abaneshwar., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 604 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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