The synergistic flame-retardant effect of silicone powder in flame retardant systems does not affect the calorific value of flame-retardant boards. Generally, the calorific value of flame-retardant boards should not exceed 3. The calorific value is a characteristic of the plastic fuel itself and is determined by the fuel’s own properties.
Each fuel has a certain calorific value, and different fuels generally have different calorific values. The calorific value of the same fuel does not change with complete combustion or with changes in the fuel’s quality.
Additionally, silicone powder is inert and does not react with strong alkalis. When silicone flame retardants burn at high temperatures, their viscosity is lower than that of polymer materials, causing phase separation. In polymer materials, the silicone flame retardant system forms a silicone-enriched layer on the surface when heated. During combustion, this layer generates a unique -Si-O- and -Si-C- key inorganic oxygen barrier protective layer and flame-retardant carbonization layer. This layer not only prevents the release of decomposition products from burning but also inhibits the decomposition of polymer materials. However, excessive addition of silicone powder can reduce the critical mechanical properties of flame-retardant modified materials (such as impact strength, elongation at break, and maximum tensile strength), accelerate aging of the materials, potentially leading to brittleness, decreased fluidity, and negatively impacting processing performance and design freedom (e.g., thin-wall molding and complex geometries).
Therefore, the addition of silicone powder in flame-retardant boards must follow the manufacturer’s recommended ratios. Thus, in flame-retardant boards, silicone powder can improve processing performance without affecting the calorific value.
