Synthesis of<i>N</i>-Alkoxy Hindered Amine Containing Silane as a Multifunctional Flame Retardant Synergist and Its Application in Intumescent Flame Retardant Polypropylene

Abstract

A novel and multifunctional flame retardant synergist, N -alkoxy hindered amine containing silane (Si-NORs), was synthesized by combining N -alkoxy hindered amine and silane coupling together through sol–gel reaction. The composition of Si-NORs was characterized by FTIR and XPS. Intumescent flame retardant polypropylene (IFR–PP) composites were prepared with different contents of Si-NOR and characterized by the limiting oxygen index (LOI), vertical burning tests (UL-94 tests), TGA, the Yellowness Index (YI), mechanical properties, and SEM measurements. The results showed that IFR–PP composites with 1 wt % Si-NORs and 25 wt % intumescent flame retardant could reach a V-0 rating in the UL-94 tests. Moreover, the thermal stability, UV stability, mechanical properties, compatibility, and char residue structure were also improved significantly, which proves Si-NOR as a multifunctional flame retardant synergist. The possible synergistic mechanism of Si-NORs was also discussed.