Halogen-Free Flame Retardant Impact on Rigid Polyisocyanurate Foam Properties
2025
Laima Vevere | Beatrise Sture-Skela | Vanesa Dhalivala | Uldis Bariss | Uldis Pasters | Nikolajs Kurma | Ugis Cabulis | Mikelis Kirpluks
This study evaluates the impact of different flame retardants on the mechanical and thermal properties of rigid polyisocyanurate (PIR) foams, focusing on formulations with isocyanate indexes of 335 and 400. The flame retardants tested include triethyl phosphate (TEP), ammonium polyphosphate (APP), aluminium hydroxide (Al(OH)3), and a combination of APP and Al(OH)3. FOAMAT®: was used to analyse the foaming kinetics, while further tests assessed density, thermal conductivity, and compression strength. TEP, a liquid flame retardant, was found to reduce peak heat release rate (pHRR) and total heat release significantly, outperforming solid flame retardants. Although solid flame retardants like APP slightly increase start times and gel times due to their non-reactive, filler role, they increase the foam&rsquo:s density and somewhat limit the effectiveness in reducing flammability. The uneven dispersion and lower compatibility of solid additives may lead to suboptimal improvements in fire resistance. APP displayed dual-phase decomposition, aiding char formation to a degree. Overall, TEP proved most effective in enhancing PIR foam&rsquo:s fire resistance, demonstrating the advantage of liquid over solid flame retardants in achieving uniform distribution and better integration with the foam matrix, thus optimising thermal insulation and mechanical performance.
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