Reductants for polyperoxides to accelerate degradation at elevated temperatures
| Autor: | Akikazu Matsumoto, Eriko Sato, Michihiro Yuri, Hideo Horibe |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Cyclopentadiene
Polymers and Plastics Diene Radical 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Hydrogen atom abstraction Photochemistry 01 natural sciences Redox 0104 chemical sciences chemistry.chemical_compound Monomer chemistry Mechanics of Materials Materials Chemistry Degradation (geology) Moiety 0210 nano-technology |
| Zdroj: | Polymer Degradation and Stability. 162:47-54 |
| ISSN: | 0141-3910 |
| DOI: | 10.1016/j.polymdegradstab.2019.01.030 |
| Popis: | The alternating copolymer of a conjugated diene monomer and oxygen, i.e., polyperoxide, is a main-chain degradable polymer and undergoes radical chain degradation by heating. During the degradation process, oxygen-centered radicals are formed and thus side reactions such as hydrogen abstraction from the polymer by the oxygen-centered radicals and subsequent coupling, which prevent the degradation, sometimes take place. In this study, in order to promote the degradation of polyperoxides only at elevated temperatures while maintaining their stability at ambient temperature, appropriate organic reductants, which do not significantly react with the polyperoxides at 30 °C but react at 100 °C, were explored. N,N-Dimethylaniline, which is a conventional reductant for redox initiation systems, initiated the redox degradation of cyclopentadiene-based polyperoxides even at 30 °C due to the very high nucleophilicity. The introduction of an electron donating group at the para position, i.e., 4-dimethylaminoacetophenone, 4-dimethylaminobenzaldehyde, and 4-dimethylaminobenzonitrile, successfully maintained the stability of the polyperoxide at 30 °C and accelerated the degradation at 100 °C due to the reduced nucleophilicity. Similar results were obtained by using 1-acetyl-2-phenylhydrazine and 1-phenyl-3-pyrazolidone (PhP) as a reductant, and PhP resulted in the most significant acceleration effect at 100 °C. The activation energy for the overall degradation of the polyperoxide in the presence of PhP was much lower than that of the polyperoxide in the absence of a reductant. In the case of sorbic ester-based polyperoxides, their stabilities at 30 °C were not maintained in the presence of the reductants and the stability was improved by increasing the 2,5 structure regarding the diene moiety in the main-chain. |
| Databáze: | OpenAIRE |
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