Thermosetting plastic is a petrochemical substance that once molded and hardened cannot be remolded.It is also called thermoset.  It is usually in a liquid form to pour in molds or it may be soft and pliable to be molded in the desired shape and size. Some thermoset materials may be in solid form to be used as semi-conductors or integrated circuits. However, once cooled and hardened into a final form, it cannot be recycled or reused. It is used as adhesives too. Some examples of thermoset plastics are polyester and epoxy resins.