Aramid

Aramid fibers are highly crystalline aromatic polyamide manufactured by extruding an acidic solution of a proprietary precursor.  Aramid fibers have very low density and high specific tensile strength when compared to commonly available reinforcing fibers.  They are best known for their use in bullet proof vests, chainsaw pants, safety gloves and other applications where cut resistance and damage tolerance are required. The main advantages of aramid fibers are:

  • Light weight

  • High impact damage tolerance

  • High tensile strength

  • Moderately high tensile modulus (midway between E-glass & HS carbon)

  • Excellent vibration damping

  • Low (negative) longitudinal thermal expansion

The main disadvantages of aramid are:

  • Very low compressive strength

  • Susceptibility to UV radiation

  • Difficult to machine

  • High moisture absorption

  • Very high transverse thermal expansion

Aramid fibers are often used in combination with other fiber types.  This allows the designer to take advantage of their unique properties and low weight, while avoiding the drawbacks.  Aramid fibers are sold in untwisted tows by denier ( g / 9,000 m ), which is related to yield or tex by the following equations