US Patent 7118689 Stabilized polychloroethylenes

Polychloroethylene, e.g., trichioroethylene and perchloroethylene, is stabilized with a stabilizing amount of a stable free radical stabilizer, e.g., a material having the 2,2,6,6-tetra(lower alkyl)-1-piperidinyloxy-yl free radical group, such as 2,2,6,6-tetramethyl-4-hydroxy-1-piperidinyloxy, or the 2,2,5,5-tetra(lower alkyl)pyrrolidinyloxy group, such as 2,2,5,5-tetramethyl pyrrolidinyloxy. Stable free radical stabilizer is removed from a polychloroethylene composition containing same by contacting the composition with silica, e.g., precipitated silica.