Effect of platinum-modified kaolin on the flame retardancy and ceramization of silicone rubber composites

Abstract

Ceramic-filled silicone rubber (SR) enhances its fire resistance through the incorporation of ceramic fillers and additives, while retaining the excellent properties characteristic of traditional SR formulations. However, conventional ceramic fillers alone are inadequate for achieving effective flame retardancy and low-temperature ceramization. In this study, platinum was uniformly deposited onto calcined kaolin via an ionic liquid-assisted reduction method to prepare platinum-modified kaolin (G-Pt), which was then incorporated into SR composites. The composites exhibited significantly improved fire safety performance, with the limiting oxygen index (LOI) increasing from 30% (SR/G45) to 34% (SR/G-Pt2), and the UL-94 rating elevated from nonrated to V-0. The peak heat release rate (PHRR) decreased from 202.6 kW/m2 (SR/G45) to 184.8 kW/m2 (SR/G-Pt1), and total smoke release was also notably reduced. After calcination at 800 °C, the flexural strength of SR/G-Pt composites reached ∼ 5 MPa, indicating effective ceramization. These results demonstrate that platinum-modified kaolin significantly improves both flame retardancy and structural stability at elevated temperatures, making it a promising additive for the development of advanced SR-based composites for high-temperature and fire-critical applications.