Biological-mechanical pretreated rice straw for constructing foam with mechanically robust and fire-retardant behaviors

To substitute petroleum-based expandable polystyrene (EPS), utilizing natural fiber to construct biodegradable foam has attracted increasing attention. Herein, we demonstrated that rice straw after clean and green biological-mechanical pretreatment is capable of manufacturing robust and fire-retardant foam by foam forming and drying under ambient temperature. The mechanical performances of the foams were effectively reinforced by the formation of numerous hydrogen bonds between silanol groups on montmorillonite (MMT) and -OH groups on rice straw fibers. The optimized foam possessed low density of 0.054 g/cm3 and high compressive strength of 56.28 kPa, which was 3.24 times higher than the original foam. Moreover, inorganic MMT endows the eco-friendly foam with satisfied flame retardancy property. Such foam can be employed as cushion to protect fragile goods when falling from a high position. Our findings boost the development of mechanically robust and fire-retardant foams in the field of logistics packaging to replace EPS cushioning materials.