Eco-friendly flame retardant comprising chitosan-based effectively enhances the flame retardancy of wood with low weight percent gain.

Nowadays, there are many types of flame retardants, whether halogenated or halogen-free, that can improve the flame retardancy of wood. However, they continue to pose a significant threat to our environment and cause a substantial increase in the weight gain rates after treatment. It is highly desirable yet challenging to develop an eco-friendly and efficient flame retardant with low weight gain rates. Here, we report a simple and fast process for making eco-friendly flame retardants (chitosan, gelatin, sodium phytate and clay) with weight gain rates of 3.7 %, which form excellent flame retardancy systems. This method can be used to create a 53.5 % reduction in peak heat release rate (pHRR) an 189 % increase in ignition time (cone colorimeter), and a 71.9 % reduction in peak temperature (alcohol spray lamps) compared to raw wood. The results displayed that the effect of flame retardancy (Decreased ratio for pHRR/Weight percent gain) was the best in the past three years. In addition, the flame retardancy mechanism is thoroughly analyzed using the techniques of Raman and so on. This study proposes a novel strategy featured by eco-friendly and simple preparation process for enhancing the flame retardancy of wood in important areas.