Synthesis of biobased phosphorus-containing flame retardants for epoxy thermosets comparison of additive and reactive approaches

Raphael Ménard (1) , Claire Negrell (1) , Laurent Ferry (2) , Rodolphe Sonnier (3) , Ghislain David (1)

1 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
2 Pôle MPA - Pôle Matériaux Polymères Avancés
3 C2MA - Centre des Matériaux des Mines d'Alès

This study presents a two-steps synthesis of novel additive or reactive phosphorus-and-sulfur-containing flame retardants (P-FR) for epoxy thermosets. The first step consists in totally epoxydizing the phloroglucinol. Then, the epoxy functions grafted are partially or totally open by a thiol bearing a phosphonate group to obtain a reactive P-FR and an additive P-FR respectively. The two synthesized P-FR are then incorporated into a DGEBA-IPDA matrix according to an appropriate approach. The impact of these P-FR on glass transition temperature (Tg) is assessed by DSC. Tg values exhibit the plasticizing effect of the additive P-FR and the loss of epoxy functionality due to the incorporation of the reactive P-FR. The thermal properties of the prepared thermosets are characterized by TGA, showing the more efficient action of the reactive P-FR in condensed phase (charring). TGA-FTIR coupling show the presence of phosphorus-containing gases released during the thermal degradation but these P-containing gases have no radical scavenging action in the gas phase. PCFC analyses prove the similar flame retardant properties of the two P-FR by reducing significantly the pHRR, the THR and the EHC. The cone calorimeter tests exhibit a strong intumescent effect of the residue brought by the two P-FR, leading to insulating expanded residue.

Mots clés: Biophenol; Epoxy thermosets; Phosphorus-containing flame retardants; Reactive vs additive approaches; Intumescence

Domaines: Chimie organique; Polymères

Raphael Ménard, Claire Negrell, Laurent Ferry, Rodolphe Sonnier, Ghislain David. Synthesis of biobased phosphorus-containing flame retardants for epoxy thermosets comparison of additive and reactive approaches. Polymer Degradation and Stability, 2015, 120, pp.300-312. ⟨10.1016/j.polymdegradstab.2015.07.015⟩. ⟨hal-01186683⟩