Siti Nur Khalidah Usri (2023) Synthesis, fire retardancy and dielectric properties of cyclotriphosphazene derivatives blended with epoxy resin. Masters thesis, Universiti Malaysia Sabah.
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Abstract
Cyclotriphosphazene is a ring compound consisting of alternating phosphorus and nitrogen atoms. Since cyclotriphosphazene compound was claimed to have excellent fire-retardant properties, this compound was used to overcome the problem of epoxy resin, which was reported to have poor fire ability. Epoxy resin was used widely in many industrial areas but restrained its further application in areas with high-fire resistance requirements. The research project concludes with four key objectives achieved, each contributing to the advancement and characterization of novel hexasubstituted cyclotriphosphazene compounds with promising applications across various domains. Firstly, a successful synthesis was achieved for hexasubstituted cyclotriphosphazene compounds featuring Schiff base and ester linking units, accomplished through multiple chemical pathways. Notably, the alkylation reaction of 4-hydroxybenzaldehyde with pentyl and tetradecylbromide produced intermediates 1a-b, while condensation of p-substituted benzaldehyde with 4-aminophenol led to intermediates 2a-b. Intermediate 3 emerged from a substitution reaction of methyl-4-hydroxybenzoate with hexachlorocyclotriphosphazene (HCCP), subsequently yielding intermediate 4. Esterification of 2a-e and 4 resulted in compounds 5a-e, distinguished by Schiff base and ester linking units with varying terminal chain lengths. These synthesized compounds hold substantial potential as versatile constituents for further investigations and practical applications. Secondly, thorough characterization of both intermediates and final compounds was carried out employing diverse spectroscopic techniques, encompassing Fourier transform infra-red spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), and CHN elemental analysis. The FT-IR spectra of compounds 5a-e revealed significant absorption bands at 1617 cm-1 (C=N stretching), 1535 cm-1 (C=C stretching), and 1238 cm-1 (C-O stretching). P=N stretching appeared at 1182 cm-1, while P-O-C bending occurred at 1011 cm-1. Notably, compound-specific characteristics such as C-H sp3 stretching (2924-2850 cm-1) for 5a and 5b, and C-Cl bending (842 cm-1) for 5c, were observed. The 1H NMR analysis exposed a distinctive proton peak of Schiff base proton at ~ δ 8.50 ppm and various aromatic protons, which resonated in the region of δ 6.50-8.50 ppm. Similarly, 13C and 31P NMR spectra provided insights into carbon and phosphorus environments, demonstrating consistent trends in chemical shifts. Thirdly, the fire retardant properties of these hexasubstituted cyclotriphosphazene compounds, when incorporated into epoxy resin, were investigated. Both thermogravimetric analysis (TGA) and limiting oxygen index (LOI) measurements exhibited improved fire resistance. Compound 5d, featuring a nitro terminal group, displayed the highest char residue with 34.2% at 700 °C. Notably, LOI testing revealed that compound 5d had the highest LOI value of 26.71%, indicating enhanced fire retardancy. The dielectric strength of these compounds was also evaluated using AC breakdown voltage, with 5d exhibiting the highest value of 24.31 kV/mm, suggesting its potential for electrical insulation applications. Lastly, the determination of dielectric strength through AC breakdown voltage measurements provided valuable data on the compounds' electrical properties. Breakdown voltages for different compounds were measured, with alkyl chain-containing compounds exhibiting lower values (21.13-23.51 kV/mm) compared to those with electron-withdrawing groups (-Cl, -NO2, -OH) (23.51- 24.31 kV/mm). The synthesized compounds' diverse performances in terms of breakdown voltage could lead to applications in electrical insulation or capacitor materials, depending on specific requirements. In summary, this research project successfully achieved its objectives of synthesizing, characterizing, and exploring the potential applications of hexasubstituted cyclotriphosphazene compounds. The findings suggest these compounds hold promise in diverse fields ranging from material science to fire safety application and electrical insulation.
| Item Type: | Thesis (Masters) |
|---|---|
| Keyword: | Cyclotriphosphazene, Epoxy resin, Fire retardancy |
| Subjects: | T Technology > TH Building construction > TH1-9745 Building construction > TH1000-1725 Systems of building construction Including fireproof construction, concrete construction |
| Department: | FACULTY > Faculty of Science and Natural Resources |
| Depositing User: | DG MASNIAH AHMAD - |
| Date Deposited: | 23 Oct 2024 11:57 |
| Last Modified: | 23 Oct 2024 11:57 |
| URI: | https://eprints.ums.edu.my/id/eprint/41306 |
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