Functionalized Attapulgite With Phosphaphenanthrene and Triazine‐Trione Groups for Improving Flame Retardancy of PBT Composites

ABSTRACT In this study, silane‐based phosphorus flame retardants (DOPO‐KH560) and silane‐based nitrogen flame retardants (TGIC‐KH550) were first synthesized via a ring‐opening addition reaction, and the DOPO‐KH560 and TGIC‐KH550 were further grafted onto the surface of ATP to obtain ATPD and ATPT flame retardants, respectively. The resulting flame retardants, ATPD and ATPT, with different phosphorus/nitrogen (P/N) ratios, were then incorporated into poly(butylene terephthalate) (PBT) at a loading of 10 wt% to improve the flame retardancy and mechanical integrity of the PBT composites. Specifically, PBT composite containing 8 wt.% ATPD and 2 wt.% ATPT achieved a V‐0 rating and an oxygen index (LOI) of 28.3%, and the peak heat release rate (pHRR) and total heat release rate (THR) decreased by 29.4% and 7.7% compared to the PBT. Due to good interfacial adhesion between ATPT and PBT matrix, the PBT/6ATPD/4ATPT composite exhibited a tensile strength of 58.7 MPa, exceeding the strength of PBT and the PBT/ATP composite by 9.7% and 8.1%, respectively. As a result, the integration of ATPD and ATPT as flame retardants not only improved fire resistance but also optimized the mechanical properties of PBT composites.