What is the difference between fiber glass, carbon fiber, and Kevlar?
Those materials are all what is considered composites because they acquire their rigidity from a composition of the woven fiber and a chemically hardened resin (usually epoxy in higher end products and polyester in lower end knock-off products). Carbon fiber and fiber glass have the most in-common properties, but carbon fiber is much stiffer for the same weight, and therefore is much more useful in products that require stiffness and lightweight. Carbon fiber is also ten times the cost of fiber glass and truly an indicator of the overall quality of the product. Kevlar is also very expensive like carbon fiber, but has different properties: Kevlar (chemical name aramid) is extremely strong in tension and bending but not near as stiff as carbon fiber. Therefore, Kevlar is best used in areas where persistent stress and bending will occur. Generally you do not see a lot of Kevlar in skate boots except over the mounting blocks where the most strain and stress occurs.
