Epoxy resins are thermosetting polymers, which are crosslinked using hardeners (curing agents). Unsaturated polyesters (UPR) are thermosetting resins. Either thermoplastic or thermosetting polymers may be used. From thermosetting plastics, alkyds and melamine resins are better than phenolic resins. Examples of thermosetting adhesives are&colon; epoxy, polyurethane, cyanoacrylate and acrylic polymers. The most common gelcoats are thermosetting polymers based on epoxy or unsaturated polyester resin chemistry. Polyester resins are thermosetting and, as with other resins, cure exothermically. These prepregs consist of wood fibers and thermosetting resins. The bobbin may be made of thermoplastic or thermosetting (for example, phenolic) materials. Induction welding is used for joining a multitude of thermoplastics and thermosetting matrix composites. The synthetic resin for such processes is a monomer for making a plastic thermosetting polymer. Decorative high-pressure laminates (HPL) sheets based on thermosetting resins, specifications. The term usually refers to thermoplastic materials rather than thermosetting ones. Other particles are insulated by the thermosetting resin. This reaction causes polymers to cross-link into acrylics, urethanes, and epoxies - See thermosetting polymers.