This paper investigates the flame retardant (FR) mechanism of action of a flexible PU foam, flame retarded with a sol-gel coating made of a mixture of tetraethoxysilane (TEOS), methyl triethoxysilane (MTES), 3-amino propyl triethoxysilane (APTES) and diethyl phosphite (DEP) in an ethanol/water solution. To build a mechanism of action, the coating as well as the residues obtained after fire testing were analyzed using solid state nuclear magnetic resonance (NMR), rheology, thermogravimetric analyses coupled with infrared detection (TGA-FTIR), microcalorimetry of combustion (MCC), smoke box and Pyrolysis Gas chromatography coupled with mass spectrometry (Py-GCMS). The coating shows an intumescent behavior upon burning exhibiting significant expansion and bubbling. The expansion occurs in two steps: a first step around 190 °C, related to the release of ethanol, and a second one around 380 °C, related to the release of non-degraded DEP, ammonia and propylene during degradation of the PU matrix. The flame retardant effect occurs (i) in the condensed phase by intumescence, which yields a thermal insulating layer made of a SiO₂ and Si-O-P network mixed with orthophosphate at the surface of the PU foam, but also (ii) in the gas phase by the release of non-degraded DEP, which acts as free radical scavenger. The coating allows the protection of the underlying PU foam during burning as well as the reduction of the amount of smoke released.

本文研究了挠性PU泡沫的阻燃（FR）作用机理，该阻燃剂是由四乙氧基硅烷（TEOS），甲基三乙氧基硅烷（MTES），3-氨基丙基三乙氧基硅烷（APTES）的混合物制成的溶胶-凝胶涂层阻燃的和在乙醇/水溶液中的亚磷酸二乙酯（DEP）。为了建立作用机理，使用固态核磁共振（NMR），流变学，热重分析与红外检测（TGA-FTIR），燃烧微量量热（MCC）对涂层以及着火测试后获得的残留物进行了分析。 ，烟箱和热解气相色谱-质谱联用（Py-GCMS）。该涂层在燃烧时表现出膨胀行为，表现出显着的膨胀和起泡。膨胀分为两个步骤：第一步是在190°C附近，与乙醇的释放有关，第二个与380°C左右的释放有关，与PU基质降解过程中未降解的DEP，氨和丙烯的释放有关。（i）通过膨胀在缩合相中产生阻燃作用，这产生了由SiO制成的隔热层₂和Si-OP网络在PU泡沫表面与正磷酸盐混合，而且（ii）在气相中通过释放未降解的DEP充当自由基清除剂。该涂层可以在燃烧过程中保护下面的PU泡沫，并减少释放出的烟雾量。