Kinetics of polymerization of N,N'-bismaleimide-4,4'-diphenylmethane with barbituric acid
| Autor: | Fu-En Yu, 余福恩 |
|---|---|
| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 The kinetics of polymerizations of N,N’-bismaleimide-4,4’-diphenylmethane (BMI) and barbituric acid (BTA) was investigated in this study. The kinetic models for both Michael addition polymerization and free radical polymerization were successfully developed. First, the free radical polymerization of BMI with BTA was completely suppressed via the aid of adding sufficient HQ. In this manner, we could focus on the kinetics of Michael addition polymerization of BMI with BTA. A mechanistic model was then developed to adequately predict the polymerization kinetics before a critical conversion (ca. 60%), at which point the diffusion-controlled polymer reactions started to predominate in the latter stage of polymerization. The Michael addition polymerization rate constants and activation energy in the temperature range 383-423 K were determined accordingly and the effect of solvent proton affinity on the kinetics in different solvents (N-methyl-2-pyrrolidone (NMP), N,N’-dimethylacetamide (DMAC), and N,N’-dimethylformamide (DMF)) were also investigated. In the second part, with the knowledge of kinetic parameters of the Michael addition polymerization of BMI with BTA taken from our earlier work, kinetic parameters for free radical polymerization including the overall initiation rate constant and the combined propagation and termination rate constants were obtained. In addition, modeling results along with experimental gelation time data showed that contribution of free radical polymerization was promoted for the polymerization carried out at a higher reaction temperature and/or a larger molar ratio of BMI to BTA. By contrast, Michael addition polymerization was enhanced with a smaller molar ratio of BMI to BTA and/or a lower reaction temperature. Finally, to gain a fundamental understanding of the reactivity of the >CH2 and >NH groups of BTA toward the two terminal －C=C－ groups of BMI, three model compounds (N-phenylmaleimide (PMI) containing one －C=C－ group, 1,3-dimethylbarbituric acid (1,3DMBTA) containing one >CH2 group and 5,5-dimethylbarbituric acid (5,5DMBTA) containing two >NH groups per molecule) and a molecular probe (hydroquinone (HQ)) were chosen for further study. It was concluded that the >CH2 group of BTA provided the main active hydrogen atoms in the isothermal polymerization of BMI with BTA in N-methyl-2-pyrrolidone (NMP) in the temperature range 373-403 K. On the contrary, the two >NH groups of BTA did not contribute to polymerization of BMI with BTA to an appreciate extent. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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