Difference Between PVC and Polycarbonate

Main Difference – PVC vs Polycarbonate

Polymers are giant molecules composed of a large number of repeating units. According to their physical properties, polymers are divided into three groups as thermosets, thermoplastics and elastomers. Both PVC and Polycarbonate are good examples of thermoplastics. The main difference between PVC and Polycarbonate is that PVC is composed of a chloride group whereas Polycarbonate is composed of a carbonate group.

Key Areas Covered

1. What is PVC
      – Definition, Formation, Properties
2. What is Polycarbonate
      – Definition, Formation, Properties
3. What is the Difference Between PVC and Polycarbonate
      – Comparison of Key Differences

Key Terms: Aromatic Ring, Elastomers, Polycarbonate, Polymers, PVC, Polyvinyl Chloride, Thermoplastics, Thermoset Plastic

What is PVC

PVC is the short name for Polyvinyl Chloride. The most accurate way of writing this name is Poly (vinyl chloride). That is because PVC is the polymer of vinyl chloride monomer. It is a synthetic plastic polymer. Vinyl chloride monomer is formed from the reaction between ethylene and chlorine gas. PVC is formed from the polymerization of vinyl chloride monomer.

The molecular formula of vinyl chloride monomer is C₂H₃Cl. There is a double bond between two carbon atoms. This double bond (unsaturation) is the reason for the polymerization of this monomer.

Figure 1: Vinyl Chloride Monomer

PVC is formed from the polymerization of vinyl chloride monomer and the polymerization process is known as chain growth polymerization. The molar mass of one repeating unit is about 62.49 g/mol.

Figure 2: Repeating Unit of Polyvinyl Chloride

PVC can be made either as a flexible plastic or a rigid plastic by the means of additives. The melting point of PVC is normally 212⁰C. Glass transition temperature is about 81⁰C. Glass transition temperature is the temperature at which the polymer transits from a hard glassy state to a rubbery state upon the increasing of temperature.

What is Polycarbonate

Polycarbonate is a type of plastic formed from the reaction between Bisphenol A and phosgene. Although either Bisphenol A or phosgene do not contain a carbonate group, the product Polycarbonate is composed of a carbonate group. Polycarbonate is also a synthetic plastic polymer.

Figure 3: Formation of Polycarbonate

The polymerization process of polycarbonate is a step growth polymerization. Here, a condensation reaction that involves two functional groups occurs (an unsaturated monomer is not involved).

The glass transition temperature of polycarbonate is about 147⁰C. The melting temperature of polycarbonate can be given as 225⁰C but it is not very accurate because the structure of polycarbonate is highly amorphous. The molar mass of its repeating unit is about 254.3 g/mol.

Difference Between PVC and Polycarbonate

Definition

PVC: PVC is a plastic and it is the polymer of vinyl chloride monomer.

Polycarbonate: Polycarbonate is a type of plastic formed from the reaction between Bisphenol A and phosgene.

Monomer

PVC: The monomer for PVC is vinyl chloride.

Polycarbonate: The monomers for polycarbonate are Bisphenol A and phosgene.

Molar Mass of One Repeating Unit

PVC: The molar mass of one repeating unit of PVC is about 62.49 g/mol.

Polycarbonate: The molar mass of one repeating unit of Polycarbonate is about 254.3 g/mol.

Presence of Functional Groups

PVC: PVC is composed of chloride groups.

Polycarbonate: Polycarbonate is composed of carbonate groups.

Presence of Aromatic Rings

PVC: PVC is not composed of any aromatic rings.

 Polycarbonate: Polycarbonate is composed of aromatic rings.

Melting Point

PVC: The melting point of PVC is about 212⁰C.

Polycarbonate: The melting point of Polycarbonate is about 225⁰C.

Glass Transition Temperature

PVC: The glass transition temperature of PVC is 81⁰C.

Polycarbonate: The glass transition temperature of Polycarbonate is 147⁰C.

Conclusion

Thermoplastics have the ability to be molded upon higher temperatures and solidifies upon cooling. Therefore, these type of plastics is used in a wide range of applications. PVC and Polycarbonate are two important and commonly used thermoplastics. The main difference between PVC and Polycarbonate is that PVC is composed of a chloride group whereas Polycarbonate is composed of a carbonate group.

Image Courtesy:

1.”Vinyl-chloride-2D” By Vinyl-chloride-2D.png: Benjah-bmm27derivative work: Kpengboy (talk) – Vinyl-chloride-2D.png (Public Domain) via Commons Wikimedia
2.”Polyvinylchloride-repeat-2D-flat” By Cvf-ps – Self made with ISIS Draw / eigene Arbeit (Public Domain) via Commons Wikimedia
3.”Synthesis of polycarbonate” CC BY-SA 3.0) via Commons Wikimedia

References:

1. Johnson, Todd. “PVC And It’s Many Uses.” ThoughtCo. N.p., n.d. Web. Available here. 10 July 2017. 
2. Scott, Chris. “Polycarbonate.” Polycarbonate information and properties. N.p., n.d. Web. Available here. 10 July 2017.