PVC is the most widely used fiber optic cable outer sheath material. It has good performances, good chemical resistance and weathering resistance, low cost, low flammability, and can meet the requirements of general occasions. Its primary functions include: While the optical fiber itself remains largely unchanged, the sheath material determines how the cable behaves in fire scenarios, outdoor environments, and long-term service conditions. The outer sheaths are used as the protective layer of the cables, which have the functions of fire prevention and moisture resistance.