Synthesis, Structure-Property Relationships of DOPO-Phosphonamidates and their Flame Retardant Application

Abstract:

Three bis-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-phosphonamidates were successfully synthesized and well characterized. The influence of these DOPO-phosphonamidates on fire performance of epoxy resin was comparatively investigated. UL-94 tests results of various EP formulations indicated that DOPO-phosphonamidates exhibited superior fire performance. The EP composite containing extremely low loading of PiP-DOPO (0.5 wt% P) may pass the UL-94 V-0 rating, while EDA-DOPO and DDM-DOPO made the EP pass the V-1 rating. Thermal degradation results of the DOPO-phosphonamidate indicated the higher thermal stability with the initial degradation temperature over 340 °C under nitrogen. Moreover, only a very small residue was observed at 800 °C for DOPO-phosphonamidates and all EP formulations under air and nitrogen, indicating the limited condensed phase interaction. DDM-DOPO with richer aromatic structures presented the highest thermal stability and left more char residues. Large amount of gas products during the combustion of PiP-DOPO rapidly released in a short time, promoting flame inhibition, which may explain its superior flame retardant efficacy among all the DOPO-phosphonamidates investigated in this study.

• Periodical: Key Engineering Materials (Volume 707)
• Pages: 102-113
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.707.102
• Online since: September 2016
• Authors: Bin Yu, Siu Ming Lo, Yuan Hu*
• Keywords: DOPO, Epoxy Resin, Flame Retardancy, Phosphonamidates, Thermal Stability

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