Synergistic Effect of SiO₂ on Intumescent Flame-retardant Polypropylene

Abstract

The flammability of polypropylene and its intumescent flame retardant composites consisting of ammonium polyphosphate (APP), pentaerythritol (PER) and SiO2 were studied and the synergistic effect of SiO2, as well as the synergistic mechanism was discussed in detail. For the composites, the content of SiO2 varied from 0 to 12 wt.% where the total addition of APP/PER/SiO2 was constant at 30 wt.%. The flammability properties were characterized by Limiting Oxygen Index (LOI) and UL-94 tests, while the synergistic mechanism of SiO2 was investigated by a combination of thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectrometry and scanning electron microscopy (SEM). The results showed that SiO2 had a synergistic effect on the PP/APP/PER system, with an optimum addition at 3.5 wt.%. The introduction of SiO2 improved the flame retardant properties of the PP/APP/PER system and the strength of the char layer.

Cu-Modified ZSM Zeolite Has Synergistic Flame Retardance, Smoke Suppression, and Catalytic Conversion Effects on Pulp Fiber After Ammonium Polyphosphate Flame-Retardant Treatment

“…To reduce the production of smoke in the combustion process, SiO 2 was used as a flame-retardant synergist in combination with APP. , The limiting oxygen index (LOI) and the amount of residual carbon (RC) have increased, indicating that the addition of SiO 2 can improve the flame-retardant effect of APP and enhance carbon layer strength, thereby reducing smoke generation. However, the use of SiO 2 as a smoke suppressant only acts as a physical barrier to reduce the generation of fine particles.…”

Synergistic effects of aluminium hypophosphite on the flame retardancy and thermal degradation behaviours of a novel intumescent flame retardant thermoplastic vulcanisate composite

“…Previous studies show that some transitional metal oxides, metal chelates, metal compounds [19][20][21][22], zeolites [23,24] and silicon-containing compounds [25,26] could serve as synergistic agents to effectively enhance the strength and stability of char layer and promote in catalysing the reactions among IFR components, which consequently improve the flame retardancy properties. Aluminium hypophosphite (AHP, Al (H 2 PO 2 ) 3 ), an industrial scale product, has been proved to exhibit obvious synergistic effect with IFR, since AHP will produce phosphoric acid at high temperatures that could promote the carbonisation of charring agent and the formation of a compact and nonporous char residue upon combustion of materials, which subsequently enhance the flame retardancy of polymer [27][28][29].…”