Eco-friendly Synthesis of Novel Phosphorus Flame Retardants for Multiple Purposes

Abstract

The synthesis methods of most parts of phosphorus (P)-based flame retardants apply harmful and toxic reagents, and the formation of byproducts is often inevitable. The synthesis of P-based flame retardants (FRs) according to the green chemistry approach has been investigated. Two FRs have been prepared via an addition reaction of phosphorus-pentoxide and alcohols. These molecules can be used as additive FRs after salt formation or as precursors for flame retardant surface treatments of natural fibers. The flame retardant efficacy of the synthesized additives was assessed in a bioepoxy resin system through UL-94 and limiting oxygen index tests, while their mode of action was determined by the investigation of gas-phase degradation products and thermogravimetric analysis (TGA). The prepared adduct was also used in the formulation of a reactive flame-retardant surface treatment for cellulosic fibers. In TGA tests, the treated fibers produced significant amounts of char residue.