What Is Meant By PVC?
PVC or Poly Vinyl Chloride is a popular synthetic plastic polymer. It stands in third position after Polyethylene and Polypropylene as the most widely produced plastic polymer.
There are two variants of PVC: Flexible and Rigid. Rigid PVC is used in construction sector for making doors and windows. It is also used for non-food packaging, cards and bottles. PVC can also be made softer by adding plasticizes, mostly phthalates. Soft PVC can be used to make electric cables, plumbing, imitation leather etc.
Pure PVC is a brittle, white solid. It is not soluble in alcohol. PVC is an excellent alternative for rubber. PVC was discovered accidentally by German chemist Eugen Baumann in 1872. It appeared as a white substance inside a jar of Vinyl Chloride, which had been left exposed to sunlight. Thereafter, many additives began to be added to PVC for getting various special features.
The process of making PVC involves polymerization of Vinyl Chloride Monomer (VCM). Suspension polymerization accounts for 80% share, 12 % by emulsion polymerization and 8% by bulk polymerization.
After chemical reaction, the remaining plastic slurry is stripped and degassed to remove any VCM. The polymer is then subject to a centrifuge to get rid of any water. In a hot air bed, the slurry is dried before pelletization or storage.
The polymers are strong and linear as monomers are arranged head to tail. Around 57% of the mass of PVC consists of Chlorine. This Chloride content gives PVC different characteristics compared to Polyethylene.
Before PVC gets into its finished form, it is converted to different compound forms using additives like plasticizers, UV stabilizers, heat stabilizers, thermal modifiers, flame retarders, biocides, smoke suppressers, pigments and blowing agents. The choice of additives depends on cost and end use of the PVC. Consult PVC door manufacturers in India for getting the right quality PVC.
Plasticizers are a common content in most Vinyl products to improve their quality. Most plasticizers are derived from Phthalic acids. They are colorless, oily substances which mix properly with PVC particles.
Heat stabilizers are also crucial. These substances reduce loss of Hydro Chloric acid which starts at 70 Degree C. Traditional stabilizers are derived from heavy metals.