Full Form of PVC :
PVC Full Form is Polyvinyl Chloride. PVC is the third most vastly produced synthetic plastic polymer. The first two are polyethylene and polypropylene. PVC is available in two forms-rigid PVC or RPVC and flexible PVC. RPVC is normally used in the construction industry for pipes and various in-profile uses like windows and doors. PVC is also termed as ‘Vinyl’ in European countries and North America. It is used in several applications including decorative sheets, flooring, artificial leather, etc. Apart from that, it is also utilized in the construction of bottles, cards (for example, membership cards and bank cards), and non-food packaging.
Flexible PVC can be obtained by the addition of plasticizers; the most commonly used is phthalates. When in flexible form, PVC is used for the purposes of plumbing, imitation leather, signage, in applications as replacements to rubber, etc. In simple terms, PVC is a form of thermoplastic, which is 43% carbon and 57% chlorine. Out of these percentages, the carbon is predominantly derived from gas or oil through ethylene; and chlorine is derived from the industrial-grade salt. PVC has made immense contributions in infrastructural developments. It has also been used in other areas due to its useful physical and chemical properties. In order to appreciate the subject-matter, here are three things that you must know:
Discovery of PVC
In the year 1872, a German Chemist by the name Eugen Baumann accidentally synthesized PVC. The polymer has been accidentally obtained inside a flask containing vinyl chloride when exposed to sunlight. Later in the 20th century, Ivan Ostromislensky, a Russian Chemist, and Fritz Klatter working for a German company named Griesheim-Elektron attempted to make application of PVC in certain commercial products. However, they failed to do so because of many difficulties such as issues relating to the processing of the brittle substance. It was only in the year 1926 that Waldo Semon, along with the B.F. Goodrich company, successfully developed a way to cause plasticization of PVC by mixing it with additional substances. The outcome of the mix was that a more flexible PVC was obtained that enabled easy processing for the purposes of commercial use.
Additives to PVC
When the polymerization process occurs, the outcome of which is always an unmodified PVC. It has to undergo conversion, before PVC can be manufactured into finished products, by the blending of additives such as UV stabilizers, processing aids, thermal modifiers, flame retardants, blowing agents, heat stabilizers, plasticizers, etc. As far as the choice of additives is concerned, it depends upon the cost performance requirements such as window frames, underground pipe, intravenous tubing, and other suitable ingredients. For quite some time, polychlorinated biphenyls (abbreviated as PCBs) were incorporated to certain PVCs as stabilizers and flame retardants.
Many vinyl products comprise plasticizers that can improve the performance characteristic. One of the commonly found plasticizers is actually derivatives of phthalic acid. In fact, materials for this purpose are chosen on the basis of their compatibility, cost, and low volatility levels. Such materials are generally oily, colorless substances which can blend adequately with the particles of PVC. It is to be noted that around 90 percent of the plasticizer market is devoted to PVC.
Heat stabilizers are one of the most commonly used additives in PVC. These agents have the capability to reduce the loss of Hydrochloric Acid (Abbreviated as HCL), which often happens when the temperature goes above 70 degree Celsius. The moment dehydrochlorination process begins it becomes autocatalytic. Many diverse agents are used such as the traditionally used derivates of heavy metals. Recently, metallic soaps have become more preferable, especially calcium stearate. There are several factors that affect the choice of a heat stabilizer for the polymer.
Properties of PVC
The following are some of the properties of PVC:
- Essentially, PVC is a thermoplastic polymer. It has high mechanical properties such as high hardness. These properties will enhance with the increase of molecular weight and reduce with the increase in temperature.
- The heat stability of a crude PVC is poor and that is why it is necessary that heat stabilizers are added in the process.
- PVC comes with good insulation characteristics.
- PVC is resistant to salts, acids, bases, and fats and therefore, it is extensively utilized in sewage piping. Apart from this, it is also found to be resistant to a few solvents.
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