Optical cable sheaths are designed to protect fibers from mechanical, chemical, and environmental stresses, with materials like PVC, PE, LSZH, and AT offering specific performance characteristics.

Common Sheath Materials and Their Properties

1. Polyvinyl Chloride (PVC)

• Widely used for general-purpose cables.
• Mechanical properties: Good flexibility, moderate tensile and abrasion resistance.
• Chemical resistance: Resistant to many chemicals and oils.
• Environmental resistance: UV and weather resistant, low flammability.
• Limitations: Produces dense smoke when burned, less environmentally friendly . 2. Polyethylene (PE)
• Includes LDPE, LLDPE, MDPE, and HDPE, each with varying density and properties .
• Mechanical properties: Excellent tensile strength, abrasion resistance, and flexibility (especially LDPE and LLDPE).
• Environmental resistance: Outstanding UV resistance, low water absorption, and excellent low-temperature performance (down to -100°C for some types).
• Chemical resistance: Stable against acids, alkalis, and most solvents; not resistant to strong oxidizing acids.
• Applications: Outdoor, direct burial, and duct installations . 3. Low Smoke Zero Halogen (LSZH)
• Flame-retardant material filled with aluminum or magnesium hydroxide.
• Mechanical properties: Good tensile strength, oil resistance, and flexibility.
• Environmental resistance: Low smoke emission, no toxic gases, withstands high pressure, and suitable for indoor/outdoor use.
• Applications: Environments with fire safety requirements, such as tunnels, buildings, and public spaces . 4. Anti-Tracking (AT) and Rodent-Proof Sheaths
• AT material: Modified PE with additives to prevent electrical tracking, used in high-voltage environments.
• Rodent-proof sheaths: Can be chemical or physical (aramid yarn or metal armor) to prevent rodent damage, suitable for underground or tunnel installations .

Key Performance Parameters

• Tensile Strength: Ability to withstand pulling forces during installation.
• Flexural Strength: Resistance to bending and deformation.
• Abrasion Resistance: Protection against mechanical wear during handling and installation.
• UV Resistance: Prevents cracking and degradation under sunlight exposure.
• Chemical Resistance: Stability against acids, alkalis, oils, and solvents.
• Temperature Range: PE can operate in extreme low temperatures; HDPE and MDPE offer wide temperature tolerance.
• Flame Retardancy: LSZH and halogen-free materials reduce smoke and toxic gas emission in fire conditions.
• Water Absorption: Low water uptake ensures long-term performance in wet environments .

Summary

The choice of optical cable sheath material depends on installation environment, mechanical stress, chemical exposure, fire safety, and temperature conditions. PE and its variants are preferred for outdoor and harsh environments, PVC for general indoor/outdoor use, LSZH for fire-sensitive areas, and AT or rodent-proof sheaths for specialized applications. Each material balances mechanical protection, environmental resistance, and safety requirements to ensure long-term cable performance.