Kevlar is used in Fibre Optic Cable to protect it.

Kevlar is a synthetic material.

Scientifically speaking, Kevlar is basically poly-para-phenelyne-terephthalamide.

Typically it is spun into ropes or fabric sheets that can be used as such or as an ingredient in composite material components.

Kevlar is a polymer.

This means that it has units that are repeating and bound together to form a much bigger molecule.

In the case of Kevlar, the repeating units form chains. These chains line up parallel to each other on their own, just like Liquid Crystals (used in the making of LCD TVs). This is known as nematic behaviour.

The chains are cross-linked with hydrogen bonds, which is what gives the material its super high-tensile strength. Kevlar has a tensile strength of about 8 times more than that of steel wire.

Tensile strength is basically the resistance offered by a material against a force to prevent elongation.

Benefits of using Kevlar:

  • It is relatively light in weight for a material that is so strong.

  • Kevlar has a very high resistance to heat (decomposes at around 450℃), and unlike most other plastics, it does not melt or even expand upon heating.
  • It is highly resistant to any kind of abrasion.

Kevlar comes in many types.

Mainly, there are different grades of Kevlar that vary in quality.

The most commonly used ones are Kevlar K29 and Kevlar K49.

Kevlar is widely used as a protective outer sheath for optical fibre cable, as its strength protects the cable from damage and kinking.

It provides cushioning protection for the fibres and can be used to pull the cable through conduit or between floors of buildings. Therefore, it is used as a strength member in fibre optic cables. Such as the ones used for audio data transmissions.

It is used as a strength member in fibre optics because optical fibres in a cable have to be safeguarded against mechanical stresses. This will ensure their optimal performance. Kevlar, normally applied in the periphery of the cable, helps provide this necessary protection.

Kevlar also brings additional functionalities that address the dielectric, weight, diameter, flexibility, and handling requirements in a fibre optic cable.

When used as a central strength member for fibre optics, where properties such as compression, flexibility, and low diameter are required, it is commonly combined with resins to form a Kevlar Reinforced Plastic (KRP).

In a fibre optic cable, many individual optical fibres are bound together around a central steel cable or high-strength plastic carrier for support.

This core is then covered with protective layers of materials such as aluminium, Kevlar, and polyethylene.



1) Kevlar is very strong and is used in a bundle to protect the fibres.

2) It is often used as the central strength member on fibre optic cables which must withstand high pulling tension during installation.

3) When it is placed around the entire cable interior, it provides additional protection for the fibres from the environment.

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