sentences:  A subset of RIM is structural reaction injection molding (SRIM), which uses fiber meshes for the reinforcing agent.The fiber mesh is first arranged in the mold and then the polymer mixture is injection molded over it.The most common RIM processable material is polyurethane (known generally as PU-RIM), but others include polyureas, polyisocyanurates, polyesters, polyphenols, polyepoxides, and nylon 6.