Industrial manufacturers in automotive, medical, plumbing and virtually every other industry use polyvinyl chloride for its versatility and durability as well as its price. Production of this thermoplastic requires much less petroleum than its polymer counterparts such as polystyrene, polyethylene and polycarbonate, allowing for significant savings.
Despite the wide use, there is growing concern for the impact polyvinyl chloride has on the environment and human health as it contains highly toxic elements that may leech into the ground or atmosphere. Although it is not typically recycled, thermal depolymerization and PVC recovery techniques are being developed to diminish the harmful effects of PVC refuse.
Still, alternatives such as wood, paper, copper, steel clay and chlorine free plastics are sought out until a more environmentally friendly solution to the PVC problem is developed.
While the chlorine present in PVC is essentially the reason for safety concerns regarding the material, it is also responsible for many of the benefits. PVC manufacturers create this plastic material through the polymerization of vinyl chloride monomeres (VCM). 57% of the mass of each polymer is chlorine.
Although mass, emulsion/dispersion and solution methods may all be utilized to produce this material, suspension polymerization is preferred. VCM and water are introduced into a reactor containing an initiator. If needed, additives such as heat stabilizers, lubricants, fillers and plasticizers are introduced at this time. These determine the properties of the particular type of PVC being produced. The reaction vessel continually mixes the solution keeping all particles suspended.
This ensures that the resulting PVC resin has a uniform particle size. After this processing is complete, the resin is dried and sieved. PVC manufacturers offer this material in several forms, typically in granulated powders, pellets, or pre-forms. As with most other plastics; extrusion, injection molding, stamping and casting are used to create stock shapes which may later be reworked into a final product or be used as such.
These include rods, billets, sheets and films. It is important to consider the dimensions, quantity and physical properties of PVC stock form or product to ensure compatibility with the intended use.