In order to meet the flame retardant requirements of the halogen-free low-smoke wire and cable standard, it is necessary to add more than 50% aluminum hydroxide. The aluminum hydroxide powder is powdery particles with a particle size d50 of less than 2um, and the polymer is generally 2-3mm. The particle size difference between the two is large, and they are inorganic and organic. Therefore, whether the uniformity of the material mixing can be ensured during the mixing process will directly affect the mechanical and flame retardant properties of the wire and cable particles.
As the content of aluminum hydroxide increases, the mixing torque continues to increase, making it more difficult to mix the materials uniformly. The elongation at the break of wires and cables gradually decreases, and the melt flow rate decreases, but the oxygen index increases due to the increase of aluminum hydroxide content. For example, in the process of raw material mixing due to short mixing time or high viscosity of the material, the changes in the components of the wire and cable pellets will lead to unqualified product mechanics or flame retardant properties, resulting in unqualified products. Therefore, whether the uniformity of the material mixing can be ensured during the mixing process will affect the performance of the wire and cable pellets.