A synthesized P/N/S oligomer flame retardant to construct superior flame-retardant, transparent, and mechanical properties epoxy resin

Jing Zhou, Yong Guo, Zhongwei Chen, Tingting Chen, Yuan Yu, Qingwu Zhang, Juncheng Jiang

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

The construction of epoxy resin (EP) composites with remarkable flame retardancy, transparency, and mechanical properties was a challenging subject in the industry. A novel P/N/S oligomer flame retardant (PALO) was synthesized of terephthalaldehyde (TPAL), 4-aminothiophenol (PATP), and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO), and employed in EP to fabricate a series of EP/PALO composites with different PALO amount. Thermogravimetric analysis (TGA) revealed that PALO exhibited remarkable thermal stability, retaining a substantial char residue of 32.2 wt% at 800 °C. Thanks to the synergy of P, N, and S, EP/PALO composites exhibited excellent flame retardancy properties. The LOI value of the EP/PALO composites saw a rise from 31.0 % to 34.2 % as the PALO content increased from 2.5 to 10 wt%, while UL-94 remained at the V-0 rating. EP/PALO also showed significant heat suppression and smoke suppression effects. The combined effects of the physical barrier from phosphate-containing char in the condensed phase, along with the flame-retardant and dilution effects of phosphorus radicals, nitrogen, and sulfur inert gases in the gas phase, contributed to the significant enhancement in flame retardancy observed in the EP/PALO composites. A notable increase in the tensile strength, flexural strength, and elongation at break of EP was triggered by the incorporation of 2.5 wt% PALO, with enhancements observed by 18.2 %, 16.6 %, and 53.1 %, respectively. Simultaneously, PALO effectively maintained the favorable transparency of EP composites under different addition amounts. Therefore, this study outlined a holistic approach for the development of oligomer flame retardants containing P/N/S and had good application potential for constructing EP composites with superior flame retardancy, transparency, and mechanical properties under different addition amounts.

Original languageEnglish
Article number102201
JournalMaterials Today Chemistry
Volume40
DOIs
StatePublished - Sep 2024

Keywords

  • Epoxy resin
  • Flame retardant
  • Mechanical properties
  • Transparency

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