Fire behavior of innovative alginate foams

• Published in: Carbohydrate polymers 2020-12, Vol.250, p.116910-116910, Article 116910
• Main Authors: Vincent, Thierry, Vincent, Chloë, Dumazert, Loïc, Otazaghine, Belkacem, Sonnier, Rodolphe, Guibal, Eric
• Format: Article
• Language: English
• Subjects: Alginate; alginates; Alginates - chemistry; calorimetry; Chemical Sciences; combustion; Composite material; Engineering Sciences; Fire behavior; flame retardants; Flame Retardants - analysis; foams; gases; heat transfer; Materials; orange peels; Polymers; polyurethanes; Polyurethanes - chemistry; pyrolysis; Radiant panel; Thermal Conductivity; Thermal insulation foam; thermogravimetry; Water - analysis
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2020.116910

[Display omitted] •Light alginate foams (density < 45 kg m-3) with high fire retarding properties.•Self-extinguishing material (water release, char formation, low combustion heat).•Critical thickness is evaluated close to 1.5–1.7 cm for enhanced flame-out.•The gases produced during combustion are less hazardous than for commercial foams.•Heat release rate decreases with thickness (remaining below 50 kW m-2). A new biosourced composite foam (AF, associating foamed alginate matrix and orange peel filler) is successfully tested for fire-retardant properties. This material having similar thermal insulating properties and density than fire-retardant polyurethane foam (FR-PUF, a commercial product) shows promising enhanced properties for flame retardancy, as assessed by different methods such as thermogravimetric analysis (TGA), pyrolysis combustion flow calorimetry (PCFC) and a newly designed apparatus called RAPACES for investigating large-scale samples. All these methods confirm the promising properties of this alternative material in terms of fire protection (pHRR, THR, EHC, time-to-ignition, flame duration or production of residue), especially for heat flux not exceeding 50 kW m−2. At higher heat flux (i.e., 75 kW m−2), flame retardant properties tend to decrease but maintain at a higher level than FR-PUF. The investigation of the effect of AF thickness shows that the critical thickness (CT) is close to 1.5–1.7 cm: heat diffusion and material combustion are limited to the CT layer that protects the underlying layers from combustion. A multiplicity of factors can explain this behavior, such as: (a) negligible heat conduction, (b) low heat of combustion, (c) charring formation, and (d) water release. Water being released from underlying layers, dilutes the gases emitted during the combustion of superficial layers and promotes the flame extinction.