How can you develop bio-based materials that resist fire?

1 Modify the chemical structure

One way to enhance the fire resistance of bio-based materials is to modify their chemical structure, either by adding flame retardants or by changing the molecular bonds. Flame retardants are substances that can reduce the ignition, combustion, or spread of fire, by interfering with the chemical reactions involved. For example, some bio-based polymers, such as polylactic acid (PLA), can be blended with flame retardants, such as phosphorus compounds, to improve their thermal stability and char formation. Alternatively, some bio-based materials can be modified by introducing cross-linking or branching in their molecular chains, which can increase their rigidity and reduce their flammability. For example, some bio-based fibers, such as cellulose or silk, can be cross-linked with agents, such as glyoxal or citric acid, to form a network that can withstand higher temperatures and prevent melting.

2 Apply a protective coating

Another way to improve the fire resistance of bio-based materials is to apply a protective coating, either on the surface or within the bulk of the material. A protective coating is a layer that can shield the bio-based material from heat, oxygen, or flames, by creating a physical barrier or by releasing inert gases. For example, some bio-based composites, such as wood or bamboo, can be coated with silica or clay nanoparticles, which can form a ceramic-like layer that can reflect heat and insulate the material. Alternatively, some bio-based materials can be impregnated with a coating that can release water vapor or carbon dioxide when exposed to fire, which can dilute the oxygen and lower the temperature. For example, some bio-based foams, such as starch or chitosan, can be impregnated with ammonium phosphate or urea, which can decompose and release gases when heated.

3 Incorporate a natural fire-resistant agent

A third way to increase the fire resistance of bio-based materials is to incorporate a natural fire-resistant agent, either from a plant or an animal source. A natural fire-resistant agent is a substance that can naturally inhibit or delay the combustion of bio-based materials, by providing a high content of moisture, ash, or minerals. For example, some bio-based materials can be derived from plants that have a high water content, such as aloe vera or cactus, which can prevent the material from drying out and catching fire. Alternatively, some bio-based materials can be derived from animals that have a high ash or mineral content, such as wool or feathers, which can form a protective char layer that can resist burning. For example, some bio-based fabrics, such as keratin or silk, can be made from wool or silk proteins, which can contain sulfur or nitrogen atoms that can form a char layer when exposed to fire.