Polymerization
Description (definition)
Polymerization is a chemical process in which small molecules, so-called monomers, are combined to form long molecular chains, the polymers. This process is the basis for the production of plastics such as polyethylene, polypropylene or polyvinyl chloride. Depending on the type of reaction, a distinction is made between chain polymerization, step polymerization and other processes. The properties of the end product, such as flexibility, hardness or heat resistance, are determined by the choice of monomers and the polymerization method.
Example
A well-known example is the production of polyethylene (PE) through the polymerization of ethylene. This process is used on a large scale in the plastics industry to produce packaging materials and technical components.
What types of polymerization are there?
– Chain polymerization: Monomers are linked together by a reactive chain, often with the help of a catalyst (e.g. polyethylene from ethylene).
– Step polymerization: Monomers react with each other in steps, producing by-products such as water (e.g. polyamides such as nylon).
– Radical polymerization: A special form of chain polymerization in which reactive radicals initiate the process.
How does the polymerization method influence the properties of the polymer?
The polymerization method determines the structure of the polymer (e.g. linear, branched or cross-linked) and therefore its mechanical, thermal and chemical properties. For example, chain polymerization often leads to thermoplastics with high flexibility, while step polymerization can produce thermosets with a rigid structure.
Why is polymerization so important in the plastics industry?
Polymerization enables the targeted production of plastics with specific properties that are adapted to the requirements of the respective industry. Whether in the automotive industry, electronics or packaging – the variety of polymers is based on the different polymerization processes.