What is the fire resistance of trihydrated aluminum in Hard Pvc Board? How is it fireproof?

Trihydrated aluminum, also known as aluminum trihydrate (ATH), is a commonly used flame retardant in PVC (Polyvinyl Chloride) formulations, including Hard PVC boards. While it is effective at reducing the flammability of PVC, it is not considered fireproof. Instead, it acts as a flame retardant by contributing to the fire resistance of the material. Here's how ATH enhances the fire resistance of PVC:
1. Release of Water Vapor: ATH contains three water molecules (tri meaning three and hydrate meaning water), and when exposed to high temperatures during a fire, it undergoes a process called endothermic decomposition. This means that it absorbs heat energy from the fire and releases the water molecules as water vapor. This water vapor has a cooling effect on the surrounding area, including the PVC material itself. It helps to reduce the temperature of the material and dilute combustible gases, slowing down the combustion process.
2. Char Formation: As ATH releases water vapor, it also promotes the formation of a char layer on the surface of the PVC material. This char layer is a carbonaceous residue that can act as a protective barrier. It shields the underlying material from direct exposure to flames, reduces the spread of the fire, and can inhibit the release of combustible gases.
3. Smoke Suppression: In addition to its fire-retardant properties, ATH can also act as a smoke suppressant. The release of water vapor and the formation of the char layer can help reduce the amount of smoke generated during combustion, which is important for fire safety in enclosed spaces.
Grey Color Rigid PVC Sheet
While ATH is effective at improving the fire resistance of PVC, it's important to note that the degree of fire resistance can vary depending on factors such as the concentration of ATH in the PVC formulation, the thickness of the PVC board, and the specific fire safety standards and regulations to which the product must adhere.
No material is truly fireproof; instead, materials can be made fire-resistant by incorporating flame retardant additives like ATH. The effectiveness of ATH and other flame retardants in enhancing fire resistance makes PVC boards safer for various applications, especially those where fire safety is a concern.