A reuse method of a used PET film includes a removal process including mechanically removing, from the used PET film, the ceramic stuck to the surface of the used PET film, a flaking process including processing the used PET film, from which the ceramic stuck to the surface has been removed, into a flake, a first pelletizing process including processing the flake into a first pellet, an adding process including adding an additive to the first pellet, a second pelletizing process including processing the first pellet, to which the additive has been added, into a second pellet, and a molding process including forming a resin molded article from the second pellet. The adding process also includes setting an IV value of the second pellet to a value within a predetermined range, by adding the additive to the first pellet.

Processes are disclosed for separating a first layer from a remainder of a tapered multilayer interlayer sheet, in which the tapered multilayer interlayer sheet is heated, and thereafter the first layer is separated from the remainder of the tapered multilayer interlayer sheet by pulling the first layer and the remainder of the tapered multilayer interlayer sheet in different directions, in a defined orientation, without the tapered multilayer interlayer sheet wrinkling or tearing.

A method for recycling prepreg materials including the steps of: a) providing at least one prepreg material including a first thermosetting polymer resin, partially crosslinked, and a weave including fibers, b) applying a vitrimerization reaction mixture to the at least one prepreg material, c) placing the at least one prepreg material coated with the vitrimerization reaction mixture on a mold of a predefined shape, d) applying a thermocompression to the at least one prepreg material at a temperature (T1) greater than or equal to the glass transition temperature (Tg) of the first resin, so as to activate the reaction between the vitrimerization reaction mixture and the thermosetting polymer leading to the formation of a vitrimer polymer and the transformation of the at least one prepreg material into a vitrimer composite material of the predefined shape.