About Polyvinyl Chloride. Polyvinyl Chloride (a.k.a. PVC) is the third most commonly produced synthetic polymer, after Polyethylene and Polypropylene. It is a white, brittle solid and it comes in two basic forms: rigid PVC (RPVC) and flexible PVC. As one of the largest thermoplastic commodity produced, Polyvinyl Chloride is in fact a global product, used in a broad range of applications due to its remarkable versatility.

This thermoplastic commodity is prepared from the vinyl chloride monomer (VCM) and can be manufactured through different polymerization processes. However, most of the commercial PVC production is based on suspension polymerization processes. To a lesser extent, PVC is produced on an industrial scale via emulsion polymerization and bulk (mass) polymerization. Polyvinyl Chloride polymers can be produced with different morphologies/molecular masses, according to the intended end use. In general, PVC is produced as a particulate with two main sizes: grains (particles) with a diameter ranging from 100 - 180 μm when it is produced via suspension and mass polymerizations, and latex of particle size 0.1 - 3.0 μm when produced via emulsion polymerization.

As one of the biggest thermoplastic commodity manufactured, Polyvinyl Chloride PVC stands out due to its distinctive characteristics stemming from the presence of a bulky chlorine atom, which imparts a highly polar nature to the polymer chain. Additionally, the essentially syndiotactic conformation of the repeat unit within the chain restricts the extent of crystallinity. As a result, PVC exhibits commendable mechanical properties and impressive stiffness even in structures with low wall thickness. PVC also demonstrates a high melt viscosity at lower molecular mass and retains its advantageous mechanical properties even when subjected to significant plasticization. Conversely, PVC is considered unstable due to molecular defeats in some of its polymer chains and self-accelerating dehydrochlorination reaction when it is heated. Therefore, PVC is always combined with various additives, such as heat stabilizers, internal and external lubricants, processing aid, UV stabilizer, impact modifier, and others. In this way, PVC can be handled and applied to several end uses. Typical applications of PVC include construction fields, domestic uses, packaging, vehicles, medical equipment, and clothing.

Polyvinyl Chloride Handling. Most PVC produced is handled in bulk and as a liquid under pressure. To reach this liquid form, the PVC powder is pressurized and fluidized in blow-eggs vessels, which possess a 2-15 t capacity and are responsible for conveying the PVC liquid via pipeline to silos for storage. These silos have a typical capacity of 100-500 t. When it comes to discharge, PVC is directly released from the silos or passed through smaller loading hoppers before being loaded into 20 t road tankers, which are the preferred transportation mode for PVC. In some cases, woven polypropylene big bags are employed to transport 1-ton batches of PVC, while 20-ton ISO metal containers are utilized for long-distance deliveries. Moreover, although PVC is not a complex material to handle, it should be stored in a cool-ventilated area and must be kept away from heat and ignition sources.

Polyvinyl Chloride Production. PVC production consists of the polymerization of vinyl chloride in such a way that different PVC manufacturing routes are related to diverse sources of this monomer. In this context, the most typical PVC production routes are based on vinyl chloride produced by the reaction of ethylene with chlorine. On the other hand, the importance of Polyvinyl Chloride waste recycling is rising as an alternative PVC-obtaining process. PVC waste includes primarily scraps from the production and use of Polyvinyl Chloride. The recycling of this waste can be mechanical, in which the waste is transformed into something new without going through chemical processes; chemical, in which the waste is again inserted into the production chain to generate more PVC; or energetical, in which the intrinsic heat of the material is removed and transformed into electrical energy. Raw materials and the respective production processes employed in the manufacturing of Polyvinyl Chloride are listed below.

Polyvinyl Chloride Uses. The uses and applications of Polyvinyl Chloride may vary according to its specification. The main forms of Polyvinyl Chloride are rigid (plastic with high resistance to impact extensively used in building applications) and flexible (prepared by the addition of plasticizers, which lower the crystallinity of polymer chains, yielding a more flexible plastic material used in flooring and medical products). PVC waste can be used as second-grade or higher-grade materials for noncritical applications, such as horticultural products and fencing.