Why use polymer composites?

There can be many secondary reasons why polymer composites may be chosen for the manufacture of particular articles or components, but the primary reason is because of weight saving for their relative stiffness and strength. As an example we can compare a carbon fibre reinforced composite with its steel counterpart. The carbon fibre composite can be five times stronger than 1020 grade steel while having only one fifth the weight. Aluminium (6061 grade) is much nearer in weight to carbon fibre composite (though still somewhat heavier), but the composite can have twice the modulus and up to seven times the strength.