Why should the carbon black content be tested for the polyethylene sheath material of optical cables?

Fiber optic cables are the main transmission carriers of optical fiber communication, and their reliability and service life are of great significance to the reliability of communication networks. During long-term use, optical cables are inevitably affected by the external natural environment, leading to the gradual deterioration of the performance of the outermost polyethylene sheath, which may ultimately affect the transmission of information within the internal optical fibers. Therefore, the environmental resistance of polyethylene sheath is one of the important indicators for evaluating the quality of optical cables, and it is also one of the important factors to ensure the service life of optical cables (25-30 years).

Shanghai Heson HS-TH-3500 Carbon Black Content Tester

Polyethylene sheath material is one of the main raw materials for optical cable products. Due to the sensitivity of polyethylene resin to natural light (mainly ultraviolet light), carbon black needs to be added as a UV light stabilizer in industrial processing to delay its photooxidation degradation caused by sunlight exposure. Carbon black is a light shielding agent that can absorb ultraviolet light, prevent the breakage and cracking of polyethylene molecular chains, and thus improve the UV resistance of the sheath. In GB/T 15065-2009 "Black polyethylene plastics for wires and cables" and YD/T 1485-2006 "Medium density polyethylene sheathing materials for optical cables", the range of carbon black content is specified as 2.60% ± 0.25%. Too little carbon black will lead to insufficient UV resistance of the material, while too much carbon black will sacrifice the physical and mechanical properties of polyethylene. Therefore, carbon black content is a very important performance indicator of polyethylene materials used for optical cable sheathing.