Multi-stage releasing water: The unique decomposition property makes attapulgite function as an unexpected clay mineral-based gas source in intumescent flame retardant

Abstract

During extensive research on intumescent flame retardants, the gas source has primarily focused on nitrogenated compounds releasing toxic gases like ammonia. This investigation revealed that attapulgite (ATP) possesses the ability to form an intumescent char layer with remarkable height within polymers. To elucidate its flame-retardant and char-expansion mechanisms, a comprehensive study was conducted. The investigation unveiled that ATP possesses a unique decomposition characteristic of multi-stage water release, distinguishing it from halloysite, montmorillonite, and kaolinite. Furthermore, ATP exhibits the capability of migrating and facilitating the formation of a char layer. Consequently, an expanded char layer is formed through ATP’s dual effects on both gas and condensed phases. Additionally, acid modification enhances its dispersibility within the composite, thereby providing better support to its char layer. This pioneering research establishes the connection between ATP and its role as a gas source, offering innovative insights into applications of ATP in gas-phase flame retardancy.