Flame-Retardancy Properties of Intumescent Ammonium Poly(Phosphate) and Mineral Filler Magnesium Hydroxide in Combination with Graphene

Abstract

Thermally reduced graphite oxide (TRGO), containing only four single carbon layers on average, was combined with ammonium polyphosphate (APP) and magnesium hydroxide (MH), respectively, in polypropylene (PP). The nanoparticle's influence on different flame-retarding systems and possible synergisms in pyrolysis, reaction to small flame, fire behavior and mechanical properties were determined. TRGO has a positive effect on the yield stress, which is decreased by both flame-retardants and acts as a synergist with regard to Young's modulus. The applicability and effects of TRGO as an adjuvant in combination with conventional flame-retardants depends strongly on the particular flame-retardancy mechanism. In the intumescent system, even small concentrations of TRGO change the viscosity of the pyrolysing melt crucially. In case of oxygen index (OI) and UL 94 test, the addition of increasing amounts of TRGO to PP/APP had a negative impact on the oxygen index and the UL 94 classification. Nevertheless, systems with only low amounts (≤1 wt%) of TRGO achieved V-0 classification in the UL 94 test and high oxygen indices (>31 vol%). TRGO strengthens the residue structure of MH and therefore functions as a strong synergist in terms of OI and UL 94 classification (from HB to V-0).

Graphene-based flame retardants: a review

“…To solve the abovementioned problems, many researchers have made significant efforts to use graphene as an adjuvant in combination with other conventional flame retardants such as intumescent flame retardants and aluminium hydroxide [46][47][48][49][50][51], melamine polyphosphate [52], carbon black [53], layered double hydroxides (LDHs) [54], brominated polystyrene and antimony trioxide (Sb 2 O 3 ) [55], and aluminium hypophosphite [56]. As shown in Fig.…”

Thermal Stability, Combustion Behavior, and Mechanical Property in a Flame-Retardant Polypropylene System

“…In particular, the damage to human life becomes serious because PP always produces CO during combustion [9][10][11][12]. To reduce flammability and release of CO, the addition of flame retardants is an effective way [13][14][15][16][17]. Moreover, it is well known, to improve the strength and poor toughness of PP, the reinforcing and toughening agents are necessary additives [18].…”

Polylactic acid biocomposites: approaches to a completely green flame retarded polymer

“…Naturally, it would be of great interest to combine these additives in a synergistic system exploiting the advantages of each component, while keeping the overall additive concentrations as low as possible. The application of this intriguing concept to combine metal hydrates with nanoparticles has been discussed previously for flame retarded composites (38)(39)(40)(41).…”