Flame Retardancy and Reinforcement–Toughening Mechanism of Epoxy Resin Modified with a Phosphorus–Nitrogen Synergistic Imidazolium Ionic Liquid
Year: 2026
Type: preprint
Abstract: Epoxy resin (EP) is widely used in engineering applications, but it has inherent flammability issues, and balancing its flame retardancy with mechanical properties also poses challenges. In this study, a phosphorus and nitrogen-containing amide-functionalized imidazoline ionic liquid − 1-(carbamoylmethyl)-2-methylimidazolium dihydrogen phosphate ([CMMIm][H 2 PO 4 ]) was synthesized, and it was introduced as a multifunctional flame retardant modifier into EP. Through LOI, TGA, cone calorimeter method, Raman spectroscopy, scanning electron microscope (SEM), and mechanical tests, the effects of [CMMIm][H 2 PO 4 ] on flame retardancy, thermal degradation, carbonization formation and mechanical properties were systematically investigated. The addition of [CMMIm][H 2 PO 4 ] significantly improved the fire resistance of EP. The LOI value of EP-4 increased from 20.41% to 30.68%, while the PHRR value decreased from 923.43 kW·m − 2 to 563.61 kW·m − 2 , a reduction of approximately 39%. At 800°C, the carbonized residue content increased from 11.64% to 16.90%, and the ID/IG ratio decreased from 0.85 to 0.78, indicating a more stable carbonization structure. Meanwhile, EP-4 exhibited tensile strength of 73.91 MPa, bending modulus of 3522.38 MPa and impact strength of 16.75 kJ·m − 2 . These results indicate that [CMMIm][H 2 PO 4 ] is an effective strategy that can enhance the flame retardancy of epoxy resin while improving its mechanical properties.
Source: Research Square
Authors: Yiru Kong, Bing Liang, Jiapeng Long
Institution: Shenyang University of Chemical Technology
Language: English
Subfield: Polymers and Plastics
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225832927
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