PVC Recycling
PVC Recycling
(Polyvinyl Chloride)
Polyvinyl chloride, (IUPAC Polychloroethene) commonly abbreviated PVC, is a widely used thermoplastic polymer. In terms of revenue generated, it is one of the most valuable products of the chemical industry. Around the world, over 50% of PVC manufactured is used in construction. As a building material, PVC is cheap, durable, and easy to assemble. In recent years, PVC has been replacing traditional building materials such as wood, concrete and clay in many areas. Despite claims that PVC production negatively affects the natural environment and human health, it is still widely used. Ofcourse it is questionable whether this is ethical or not.
There are many uses for PVC. As a hard plastic, it is used as vinyl siding, magnetic stripe cards, window profiles, gramophone records (which is the source of the term vinyl records), pipe, plumbing and conduit fixtures. The material is often used in Plastic Pressure Pipe Systems for pipelines in the water and sewer industries because of its inexpensive nature and flexibility. PVC pipe plumbing is typically white, as opposed to ABS, which is commonly available in gray as well as white.
It can be made softer and more flexible by the addition of plasticizers, the most widely-used being phthalates. In this form, it is used in clothing and upholstery, and to make flexible hoses and tubing, flooring, to roofing membranes, and electrical cable insulation.
Polyvinyl chloride is produced by polymerization of the monomer vinyl chloride, as shown. Since about 57% of its mass is chlorine, creating a given mass of PVC requires less petroleum than many other polymers.
PVC- or Vinyl Recycling has historically been difficult to perfect on the industrial scale. But within the last decade several viable methods for recycling or upcycling PVC plastic have been developed. One of the several new methods of PVC recycling is Vinyloop®.
The technical process of Vinyloop can be described fairly simply; it includes only 6 main steps. To begin the cycle, composite waste is collected and brought to the plant. Much of the material is preprocessed but some of this step takes place in the factory. Some operations that may be performed are, “a cleaning step (washing, etc.) reducing the size for fast dissolution (by cutting, grinding, milling, etc.) and a homogenization step.”
After pre-treatment, the material is sent to a dissolution chamber where the solvent, methyl ethyl ketone, dissolves the PVC and its additives. While these factors are dissolved or suspended, the insoluble materials of the original composite remain out of solution and can thus be removed in subsequent steps.
The separation of the insoluble materials occurs in the next tank. There are many techniques to filter the solid from the solution such as, “centrifuging, decanting, or cycloning,”, the particular method used is mandated by each individual situation. “After separation, the secondary material is: washed with pure hot solvent to eliminate virtually all of the dissolved PVC compound, stripped with steam to recover all the solvent, then discharged.” In this way all material is removed from the PVC. This is a very important step to yield pure PVC material for reuse.
The next stage in the process is the precipitation of the dissolved PVC. At the onset of this stage, it is possible to integrate more additives into the dissolved PVC to achieve a variety of characteristics. At the Ferrara Plant, a plasticizer is added to the PVC in order to generate a more flexible and less brittle product. Steam is then injected into the solution, evaporating the solvent completely, leaving an aqueous slurry of PVC and additives. The unwanted material from the composite as well as the solvent are thus removed. The evaporated solvent condenses in its original chamber, ready to dissolve another batch of composite material. This closed loop cycle has an effective retention rate of 99.9%, rendering the solvent a technical nutrient in this process.
The final stage in the Vinyloop is the drying phase. The aqueous solution of PVC is dried and the effluent water filtered to remove impurities. The dry R-PVC forms pellets (a significant occurrence due to that form’s ease of use in the plastics industry). Dry pellets are easy to package and ship out to be molded into other products. Many times these pellets can comprise 100% of the material for a new product, but when not, any percentage of R-PVC can be added to virgin PVC in product formation.
Heathland searches to recycle plastics, including PVC, in ways that are best suitable for people and environment. Recycling happens in-house and at partner companies in Europe and/or Asia. Since the market for plastic recycling is very international, often it is difficult to keep track of how and where scrap plastics are recycled. Heathland works with partners who are qualified, have sufficient certification, and have set quality standards for the circumstances in which plastic materials are processed. This way, the company can keep as much control as possible on the circumstances in which it’s plastics are recycled. If you are interested in this way of recycling, whether your company is a collector, manufacturer, servicer or end-user, please contact us for possibilities.