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It is a mechanical recycling process using a solvent to separate PVC from other materials. This solvent turns in a closed loop process in which the solvent is recycled. Recycled PVC is used in place of virgin PVC in various applications: coatings for swimming pools, shoe soles, hoses, diaphragms tunnel, coated fabrics, PVC sheets. [73]
It is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC). Vinyl chloride is a colourless flammable gas that has a sweet odor and is carcinogenic. Vinyl chloride monomer is among the top twenty largest petrochemicals (petroleum-derived chemicals) in world production. [2]
80–90% of world production is used in PVC, much of the rest is used in cellulose acetate. For most products loadings are between 10 and 35%, high loadings are used for plastisols: 34% Flame retardants: 1–30: Being petrochemicals, most plastics burn readily, flame retardants can prevent this: Brominated flame retardants, chlorinated paraffins
Two layers of PVC are laid down in a continuous extrusion process; the top layer is weatherable and durable material, which comprises up to 25% of the siding thickness. This capstock can include about 10% titanium dioxide, depending on the color, which is a pigment and provides resistance to breakdown from UV light.
This process is the same as a regular extrusion process up until the die. There are three main types of dies used in this process: annular (or crosshead), spider, and spiral. Annular dies are the simplest, and rely on the polymer melt channeling around the entire cross section of the die before exiting the die; this can result in uneven flow.
In the process, chlorine gas is decomposed into free radical chlorine which is then reacted with PVC in a post-production step, essentially replacing a portion of the hydrogen in the PVC with chlorine. Depending on the method, a varying amount of chlorine is introduced into the polymer allowing for a measured way to fine-tune the final properties.
This is an accepted version of this page This is the latest accepted revision, reviewed on 4 March 2025. Manufacturing processes This section does not cite any sources.
Besides plastics production, plastics engineering is an important part of the industrial sector. The latter field is dominated by engineering plastic as raw material because of its better mechanical and thermal properties than the more widely used commodity plastics.