n Joining plastics to themselves of dissimilar materials by means of solvents (see  Solvent Cementing), dopes, or chemical cements. Dope adhesives comprise a solvent solution of a plastic similar to the plastic to be joined. Chemical cements, the only type suitable for thermosetting plastics, are based on monomers or semi-polymers or semi-polymers that polymerize in the joint to form a strong bond. See  Adhesive.