Synthesis of Hyperbranched Macromolecule PTECK and Its Flame Retardant Effect on Polypropylene

ABSTRACT In this study, a hyperbranched macromolecular flame retardant (PTECK) containing nitrogen, phosphorus, and silicon was synthesized using cyanuric chloride (TCT), γ‐aminopropyltriethoxysilane (KH550), triethyl phosphate (TEP), and ethylenediamine (EDA) as starting materials. The chemical structure of PTECK was systematically characterized by Fourier‐transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and elemental analysis (EA). Subsequently, PTECK was combined with ammonium polyphosphate (APP) to prepare a flame‐retardant polypropylene (PP) composite via melt blending through hot pressing. Flame retardancy evaluations demonstrated that the incorporation of 6.67 wt% PTECK and 13.33 wt% APP into PP resulted in a limiting oxygen index (LOI) value of 30.3% and achieved a UL‐94V‐0 classification. Compared to neat PP, the peak heat release rate (PHRR) and total heat release (THR) of the PP/PTECK/APP composite were reduced by 78.2% and 68.3%, respectively, while the residual char yield reached 42.5%. Furthermore, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Raman spectroscopy (RS), X‐ray photoelectron spectroscopy (XPS), and infrared spectroscopy were employed to analyze the gaseous products and char residue, thereby elucidating the underlying flame retardancy mechanism.