Mechanically robust cellulose nanofiber/sepiolite aerogel composites with superior flame retardant properties

Abstract

Lightweight, biodegradable multifunctional cellulose nanofiber (CNF) aerogel shows great potential in the fields of thermal insulation, electronic equipment and oil contaminant removal. However, its high fire risk and poor mechanical performance severely limit its extensive application. In this work, CNF aerogel with improved flame retardant and mechanical properties was successfully prepared by incorporating sepiolite (SEP) via an ice template-assisted strategy. The obtained results showed that the thermal stability and flame retardancy of CNF/SEP (CS) aerogel were significantly enhanced. For instance, the peak of heat release rate and total heat release of CS_2.5 with a mass ratio of SEP to CNFs of 5: 1 were reduced by 72.6% and 47.2%, respectively, relative to those of pure CNF aerogel. Furthermore, its limiting oxygen index value exceeded 70%, and reached UL-94 V-0 rating. Moreover, the CS_2.5 composite showed a high compressive strength of 121.1 kPa. Therefore, this study provides a facile strategy for fabricating fire safe and mechanically robust CNF aerogels, which is expected to broaden their application scope.