Flame-Retardant and Smoke-Suppressed Silicone Foams with Chitosan-Based Nanocoatings

Abstract

Flexible silicone foams (SiFs) are high-performance but flammable materials that emit dense smoke in a fire. Two type of low-cost, eco-friendly nanocoatings, i.e., chitosan (CH)/ammonium polyphosphate (APP) and CH/montmorillonite (MMT), were fabricated on SiFs through a layer-by-layer (LbL) assembly. With seven bilayers (BL) of CH/APP coatings, the limiting oxygen index (LOI) increases from 20.2% to 23.8%, the peak heat release rate (pHRR) decreases by 27.6%, and the total smoke production (TSP) decreases 42%. Further deposition of CH/APP, however, partly damaged the fire resistance. In contrast, fire hazard and smoke release of CH/MMT coated SiFs were monotonously reduced. Every 7 BL of coating leads to ca. 12% reduction of TSP. Moreover, thermogravimetric analysis (TGA) was used to follow the pyrolysis of the coated foams, and scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX) were applied to analyze the char residues systematically.

Flame retardancy and smoke suppression of silicone foams with microcapsulated aluminum hypophosphite and zinc borate

“…To improve the flame retardancy and smoke suppression of SiFs, relevant investigations were employed. Deng et al fabricated SiFs with seven bilayers of chitosan/ammonium polyphosphate coatings; the limiting oxygen index (LOI) increased from 20.2 to 23.8 vol%, the peak heat release rate (HRR) (PHRR) decreased by 27.6%, and the total smoke production (TSP) decreased by 42%. Chruściel and Leśniak prepared flame‐retarded SiFs with 15‐wt% melamine and 15‐wt% expanded graphite, which achieved an LOI of 41 to 43 vol%.…”

Construction and flame‐retardant performance of layer‐by‐layer assembled hexagonal boron nitride coatings on flexible polyurethane foams

“…Instead, flame‐retardant coatings are an effective and convenient method for introducing concentrated flame‐retardant materials onto the surface of FPUFs without altering its mechanical properties . More recently, layer‐by‐layer (LbL) assembly has been used to fabricate flame‐retardant coatings on various substrates; this is a versatile and cost‐effective method involving the alternate deposition of selected chemical species on substrate surfaces under driving forces such as electrostatic attraction, hydrogen bonding, and covalent bonding . For LbL‐assembled flame‐retardant coatings, previous studies have shown that the choice of flame‐retardant materials is key in designing highly effective flame‐retardant coatings.…”

Effects of platinum compounds/superfine aluminum hydroxide/ultrafine calcium carbonate on the flame retardation and smoke suppression of silicone foams

“…[4][5][6] However, because of the abundant hydrocarbon groups on its side chain, SR is a combustible material; it can combust and release choking smoke once ignited. 8 When white carbon black was added during the foaming process, the SiFs could self-extinguish without any toxic gas release. Therefore, the flame retardation properties of SiFs warrant study.…”

“…7 Deng et al fabricated flame-retardant and smoke-suppressing SiFs with seven bilayers of chitosan/ammonium polyphosphate coatings; the LOI increased from 20.2 to 23.8%, the peak heat release rate (PHRR) decreased by 27.6%, and the total smoke production (TSP) decreased by 42%. 8 When white carbon black was added during the foaming process, the SiFs could self-extinguish without any toxic gas release. 9,10 In addition, inorganic fillers (e.g., asbestos, kaolin, and carbon nanotubes) and artificial fibers are widely used in flameretardant SiFs.…”