Flame-Retardant and Degradable Cellulose Micro/Nanofiber Films for Packaging Materials

Cellulose, as the main structural component of plant cell walls, has gained widespread applications in many high-end fields due to its outstanding physicochemical properties, such as renewability and biodegradability. To reduce reliance on virgin petro-based materials and construct sustainable, high-performance biobased structural materials, biodegradable cellulose materials have emerged as a crucial Frontier in research. However, its poor fire-resistant property strongly limits the practical application of cellulosics in many fields. Here, we design a biodegradable biobased composite film with a three-dimensional network structure by introducing alginate and calcium ions into cellulose micro- and nanofibers. Specially, sodium alginate is introduced into the network of the composite film and subsequently by cross-linking with calcium ions to enhance the flame retardancy of cellulose fibers film and improve the structural integrity of the film. As a result, the limiting oxygen index of NCF/SA-Ca reached 38%, with a reduction of 72.3% in the peak heat release rate. The limiting oxygen index of BCF/SA-Ca reached 35%, with a reduction of 66.6% in peak heat release rate. Furthermore, both materials exhibited a higher residual char in thermogravimetric analysis, indicating excellent flame-retardant properties. Therefore, this flame-retardant and biodegradable cellulose composite film can replace traditional membrane materials and gain wider applications in practical life, such as flame-retardant packaging materials.