Enhancing Flame-Retardant Properties of Polyurethane Composites Using N-β-(Aminoethyl)-γ-aminopropyl Trimethoxysilane and Carbon Black Co-Modified Ammonium Polyphosphate

The search for a straightforward method to obtain efficient, affordable, and long-lasting flame retardants with both desirable flame-retardant and mechanical properties for polyurethane (PU) composites remains a significant challenge. In this study, the surface of ammonium polyphosphate (APP) was modified using N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane (KH792) via an ion-exchange reaction, and the modified APP was coated with nanoscale carbon black (CB) to obtain CBAPP. CBAPP demonstrated good compatibility within the PU matrix and notably increased the tensile strength of the PU composites. Furthermore, CBAPP significantly enhanced the flame-retardant properties of the PU composites. The CBAPP/PU composite with a CBAPP mass fraction of 20% achieved a limiting oxygen index of 41.5% and a UL-94 class of V-0. According to the results of this study, our modification approach can be applied to develop other high-performance flame-retardant polymer-based composites, representing a significant contribution to the field of fire safety materials.