How Stiff Is Aramid Fiber?

The stiffness of different types of fibers is as follows:

Glass fiber fabric - from 72GPa (standard E-glass) to 87GPa (S-enhanced strength glass fabric);

Carbon fiber fabric - from 230GPa (Toray T300) to 588GPa (Toray HM grade M60J);

Aramid fiber fabrics - from 96GPa (standard aramid is Kevlar 129) to 186GPa (aramid used in the aircraft/aviation industry is Kevlar 149)

To summarize, aramid composites made from standard fabrics are 30-40% stiffer than glass fiber composites and 50% less stiff than carbon fiber composites.