Synergistic Flame-Retardant Effect of Aluminum Diethyl Phosphinate in PP/IFR System and the Flame-Retardant Mechanism

Abstract

Synergistic flame-retardant effect of aluminum diethyl phosphinate (AlPi) in intumescent flame retardant polypropylene (PP/IFR) system and the flame-retardant mechanism were investigated. The flame retardancy of PP/IFR/AlPi (the mass ratio of IFR to AlPi is 2 : 1) was the best, which was proved by the results of the limiting oxygen index (LOI) test, UL-94 test, and cone calorimeter test ( CCT) test. Here, the LOI value of the sample was as high as 34% and passed the V–0 rating in UL–94 test. The peak heat release rate (PHRR) decreased by 92.57%, the total heat release (THR) reduced by 90.52%. Thermogravimetric (TGA) data showed that the introduction of AlPi improved thermal stability and changed the thermal degradation behavior of PP/IFR composites. Interestingly, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS) and laser Raman spectroscopy (LRS) proved that PP/IFR/AlPi had formed more residual carbon, but the flame retardancy was worse than PP/IFR/AlPi. This is because when the mass ratio of IFR to AlPi is 2 : 1, the synergy between IFR and AlPi was significant, gas-phase flame retardant and condensed-phase flame retardant reached a balance and obtained the best flame retardant effect.

Preparation of a novel Fe‐MOF as the flame retardant synergist and its application in polystyrene

“…9,10 It synergistically reacts through an acid source, a charring agent and a blowing source to create an expanded char layer, acting as the protective barrier to prevent the spread of heat and smoke. 11,12 Though IFR exhibits certain flame retardant performance within polymeric matrix, its poor compatibility results in the deterioration of mechanical properties for substrates. 13,14 Thereby, the use of synergists is one of the most practical methods, for the synergists can reduce the amounts of IFR that have been incorporated while maintaining the same or even better flameretardant performance.…”

“…To further improve the efficiency, the intumescent flame retardant (IFR) system which combines various halogen‐free FRs has been established 9,10 . It synergistically reacts through an acid source, a charring agent and a blowing source to create an expanded char layer, acting as the protective barrier to prevent the spread of heat and smoke 11,12 . Though IFR exhibits certain flame retardant performance within polymeric matrix, its poor compatibility results in the deterioration of mechanical properties for substrates 13,14 .…”