In this paper, the fire retardant properties of two magnesium dihydroxide (MDH) were compared into glass fiber reinforced polyamide 6 (PA6 GF). The difference between the additives lies in the presence of a vinylsilane treatment at the surface of one of the two MDH (H5A grade) whereas the other is a non-treated MDH (H5 grade). The investigations showed that better fire properties were obtained with PA6 GF/H5A formulation compared to the PA6 GF/H5 one. More precisely, a higher UL-94 rating, a higher glow wire ignition temperature (GWIT) and a higher time to ignition (TTi) at the mass loss calorimeter (MLC) were obtained. To understand the differences between H5 and H5A in terms of fire performances, the mechanism of degradation of the two fire retarded (FR) formulations was investigated, analyzing both the gas phase and the condensed phase. A significant part of the study was also devoted to the characterization of the ceramic protective layer formed thanks to the use of MDH. The analysis of the gas phase revealed that the degradation products of the two FR formulations were similar. Moreover, as shown by the condensed phase analysis, no chemical reaction occurs between PA6 and H5 or H5A, proving that the MDH surface treatment was not involved in chemical reactions during the processing of the formulation or its degradation. On the contrary, the main differences between the two formulations concern the properties of protective layer formed during the degradation. It was shown that the silane treatment and the MgO formed during MDH dehydration lead to the formation of a cohesive structure between the glass fibers when the material degrades, resulting in a highly insulating and resistant protective layer.

本文将两种氢氧化镁（MDH）的阻燃性能与玻璃纤维增​​强聚酰胺6（PA6 GF）进行了比较。添加剂之间的区别在于，在两种MDH（H5A级）之一的表面存在乙烯基硅烷处理，而另一种是未经处理的MDH（H5级）。研究表明，与PA6 GF / H5相比，PA6 GF / H5A配方具有更好的防火性能。更精确地，在质量损失量热仪（MLC）下获得了更高的UL-94等级，更高的灼热丝点火温度（GWIT）和更高的点火时间（TTi）。为了了解H5和H5A在防火性能方面的差异，研究了两种阻燃（FR）配方的降解机理，同时分析了气相和冷凝相。该研究的重要部分还致力于表征由于使用MDH而形成的陶瓷保护层。气相分析表明，两种阻燃剂配方的降解产物相似。而且，如凝聚相分析所示，PA6与H5或H5A之间没有发生化学反应，证明在制剂加工或降解过程中，MDH表面处理不参与化学反应。相反，两种制剂之间的主要区别涉及降解期间形成的保护层的性质。结果表明，当材料降解时，硅烷处理和MDH脱水过程中形成的MgO会导致玻璃纤维之间形成粘结结构，