Flame retardancy and high-value utilization of industrial solid waste fly ash in cellulose materials

Cellulose is a bio-based material that has garnered increasing research interest due to its abundant reserves and excellent properties. However, its inherent flammability limits its widespread use. This study addresses this issue by combining cellulose with industrial waste fly ash (FA), not only mitigating its flammability but also transforming FA into a value-added product. Through hot pressing and freeze-drying processes, flame-retardant cellulose/FA films and foams were developed. This experimental method not only enhances the application potential of cellulose but also promotes the high-value reuse of FA, aligning with sustainable development principles. SEM images reveal good interaction between FA and cellulose. In terms of thermal performance, the maximum decomposition rates of C1-Fx and C2-Fx decreased systematically with increasing FA content. The addition of FA significantly improved flame retardancy, with the limiting oxygen index (LOI) of C1-F30 and C2-F30 reaching approximately 31% and 29%, respectively. Furthermore, the peak heat release rate of C2-Fx significantly decreased from 363.6 to 118.2 kW/m², and the total heat release dropped from 7.3 to 4.1 MJ/m². In summary, this study successfully utilized industrial waste FA to develop a bio-based flame-retardant material through a straightforward process, offering a viable solution to enhance the flame retardancy of cellulose and promote the reutilization of industrial waste.