Low density polyethylene (LDPE) is good sheathing material for fiber optic cables. LDPE offers low cable shrinkage compared to HDPE and MDPE. However Abrasion resistance of LDPE is inferior to HDPE and MDPE or LLDPE. Cable shrinkage and resulting loss increase in fiber optic cables is a problem at low environmental temperatures.
In this session our focus is to outline the requirements of Low Density Polyethylene (LDPE) to be used for sheathing optical fiber cables. Let us consider the black low density polyethylene.
The LDPE shall contain uniformly dispersed carbon black of such a quantity that good weather resistance is reached. The carbon black shall be of Channel or Furnace type.
The particle size (diameter) of carbon black shall be less than 20 nm on an average. The material shall not generate hydrogen in sufficient quantities to degrade the performance of optical fiber cable transmission.
Requirements:
| S # | Attribute | Value | Test Method |
| 1 | Melt Flow index, 190°C, 2.16 kg | ≤ 10 g/10 min | ASTM 1238 |
| 2 | Oxidation Induction Time, 180°C | ≥ 30 minutes | ASTM D 3895 |
| 3 | Carbon Black Content | 25 ± 0.25 % | ASTM D 1603 |
| 4 | Carbon Black Dispersion | Uniform | ASTM D 3349 |
| 5 | Tensile Strength | ≥ 14 MPa | ASTM D 638 |
| 6 | Elongation at Break | > 400 % | ASTM D 638 |
| 7 | Shore D Hardness | ≥ 40 | ISO R 868 |
Test Certificate: Each incoming delivery/ batch shall be accompanied by a test certificate.
Packing: The material shall be packaged in standard commercial containers or bags, so constructed as to ensure safe transportation.
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