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How does polymerization work?

Published in Polymer Chemistry 2 mins read

Polymerization is the process where small molecules combine to form larger molecules, ultimately leading to the creation of polymers used in various plastic products.

Understanding Polymerization

Polymerization involves linking together many smaller molecules, known as monomers, to create a large molecule called a polymer (or macromolecule). Think of it like connecting many individual Lego bricks (monomers) to build a large Lego structure (polymer).

The Building Blocks: Monomers

Monomers are the fundamental units that repeat in a polymer chain. Common examples include:

  • Ethylene (used to make polyethylene)
  • Propylene (used to make polypropylene)
  • Vinyl chloride (used to make polyvinyl chloride or PVC)

The Chemical Combination Process

During polymerization, monomers undergo a chemical reaction that joins them together. This reaction typically involves the formation of covalent bonds between the monomers. There are various mechanisms for polymerization, but they generally fall into two main categories:

  1. Addition Polymerization: Monomers add directly to each other in a chain reaction. No atoms are lost during this process. A common example is the formation of polyethylene from ethylene monomers.

  2. Condensation Polymerization: Monomers combine, and a small molecule, such as water, is eliminated. An example includes the formation of polyester.

From Polymerization to Plastic Products

The polymers created through polymerization are the raw materials for countless plastic products. These polymers are then processed through various methods like:

  • Extrusion: Shaping the polymer by forcing it through a die.
  • Injection Molding: Injecting molten polymer into a mold.
  • Blow Molding: Inflating molten polymer inside a mold.

These processes give the polymers their final shape and properties, allowing them to be used in everything from plastic bottles to car parts. The reference provided states that the polymers created through polymerization are processed to create various plastic products.

Term Definition Example
Polymerization Process of combining small molecules (monomers) to create larger molecules Creating polyethylene from ethylene
Monomer Small molecule that combines to form a polymer Ethylene, Propylene
Polymer Large molecule made of repeating monomer units Polyethylene, Polypropylene, PVC