Hi MuuMuuu, it's not carbon fiber.
It's a mat used to soundproofing trucks. This mat has an adhesive. After we place it, we mold it using a heating gun. I think that mat core is made by a kind of asphalt. It melts easily when we heat it. Upper layer seem to have a plastic (or rubber) layer.
All my car roof has been isolated with this material. Now I have to glue it on doors and rear panels.