Tenax is the brandname of Toho Tenax owned by Teijin for a carbon fiber.Tenax-7R is an adhesive particularly suited for welding plastics . Tenax is the brandname of Toho Tenax owned by Teijin for a carbon fiber.Tenax-7R is an adhesive particularly suited for welding plastics . Tenax is also a brand name for Poly(2,6-diphenylphenylene oxide), a porous polymer.