The raw material that is used for the synthesis of synthetic fibers is-

Synthetic fibers are synthesized from raw materials called petrochemicals. 

Petrochemicals are derived from hydrocarbons. These hydrocarbons are derived from fossil oil & fossil fuel and mainly contain carbon and hydrogen.

Fibers are the foundation of all fabrics and can be derived from man-made, animal, or plant sources. They have created either a small unit or a polymer made up of several repeating monomeric building units. 

Examples include rayon, nylon, and polyester.