One-Pot Synthesis of Silicone-Urethane Hybrid Foam and Comparison of Flame Retardant, Rheological, and Mechanical Properties with Polyurethane Foam

Abstract

Extensive research has been conducted on the flame hazards and toxic gas emissions of polyurethane foam (UF) under fire exposure. This study focuses on designing and fabricating silicone-urethane hybrid foam (SUF) to enhance fire safety for transportation seating applications. Poly(dimethyl)siloxane (PDMS) foam is recognized for its excellent mechanical strength, high-temperature stability, and superior flame resistance, making it suitable for various applications. Utilization of these properties requires optimized catalysts and reaction conditions that enable the simultaneous curing and foaming of silicone foam (SF) and UF. Tin(II) 2-ethylhexanoate (Sn(OCT)2) was successfully utilized to promote the reaction between bifunctional isocyanates and polyols, successfully curing vinyl-terminated PDMS under specific conditions. The catalytic role of Sn(OCT)2 in both the foaming and gelation processes of both silicone and urethane chemistry was elucidated. The SUF exhibited exceptional flame-retardant properties, achieving a 44.55% reduction in the peak heat release rate (PHRR) compared to UF, owing to the network structure of PDMS and its synergistic and barrier effects. Furthermore, PDMS maintained strong mechanical properties within the hybrid foam through crosslinking reactions. This study presents a straightforward approach to manufacturing SUF with outstanding fire safety performance.

Keywords: Polyurethane foam, Silicone foam, Hybrid foam, Tin octoate, Flame-retardant, Viscoelasticity