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Plastic Compounds and Additives / Compounding


In order for a polymer to be used to create what we know as the end plastic product it first needs to be compounded.

By definition compounding is the mixing in of additives with a polymer to improve the properties of the polymer.

At the beginning of the compounding process the polymer is normally in a powder, bead or pellet form (however it can also be a solution, melt or suspension). The final step of the process is the conversion of the melt into granules.

The production of a compound takes three steps:

  1. Mixing – bringing together the different ingredients.

  2. Compounding – Rough mixture of materials is mixed properly while hated into a paste or melt.

  3. Granulation- The mixed material is shaped so that it can be cut into granules.

So what is an additive and why is it important for compounding a polymer?

A compound cannot be made without mixing additives to the polymer. An additive is needed to change the properties of the material making it harder, flexible, cheaper or used to prevent degradation of the polymer.

We can list two groups of additives: modifying additives and protective additives.

Modifying additives include: As the name suggests modifying additives modify the physical properties of the polymer.

  1. Plasticisers

  2. Fillers

  3. Extenders

  4. Chemicals (crosslinking agents, impact modifiers, blowing agents)

  5. Pigements

Protective additives include: As the name suggests protecive additives are used to protect the polymer from degragation.

  1. Antioxidants

  2. Heat stabilisers

  3. UV stabilisers

  4. Antistatic agents

  5. Lubricants (internal and external)

  6. Processing aids

For more information on compounds and additives contact me via the contact form!

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