Introduction to Plastics Additives

Every activity in modern life is influenced by plastics and many depend entirely on plastics products. Imagine cars without synthetic bumper, dashboards, steering wheels and switches; medicine without plastic hypodermic syringes and artificial hip joints. And what about telecommunications, dependent on plastic telephones, circuit boards and cable insulation. Our entertainment and leisure relies on the unique combination of characteristics offered by plastics in sports equipment and clothing, CDs, video and audio tape, television and cinema - indeed you wouldn't be able to read this over the internet without plastics!

All these plastics products are made from the essential polymer mixed with a complex blend of materials known collectively as additives. Without additives, plastics would not work, but with them they can be made safer, cleaner, tougher and more colourful. Additives cost money, of course, but by reducing production costs and making products last longer, they help us to save money and conserve the world's precious raw material reserves. In fact, our world to day would be a lot less safe, a lot more expensive and a great deal duller without the additives that turn basic polymers in to useful plastics.

Antimicrobials/Biostabilisers

Function: 
Help prevent deterioration of plastic materials where part of the material might be susceptible to microbiological attack. Such attacks can cause staining, discolouration, odour and loss of aesthetics but more importantly, loss of electrical insulating properties, hygiene and overall loss of mechanical properties in the material.

Antioxidants

Function:
Help prevent "oxidation", the polymer reacting with oxygen. Oxidation can cause loss of impact strength, elongation, surface cracks and discolouration. Antioxidants help prevent thermal oxidation reactions when plastics are processed at high temperatures and light-assisted oxidation when plastics are exposed to UV light.

Antistatic Agents

Function:
Help to prevent the build up of static electric charge.  Plastics are generally insulating and so have the capacity to build up static charges on the surface which greatly disturb processing procedures and can be an issue for hygiene and aesthetics.

Biodegradable Plasticisers

Function:
Used to make plastics softer and more flexible and to enhance the degradability of the product.

Blowing Agents

Function:
Form gases in the plastic to produce a foam material.  The blowing agents form gases by breaking down on heating at a pre-determined temperature and form a foam structure within the plastic's polymer matrix.

External Lubricants

Function:
To prevent damage to plastics or the mould during processing. Applied to the material or directly to the machine to allow processing without damage.

Fillers/Extenders

Function:
Natural substances used to improve strength and lower the cost of the material. Usually mineral-based, fillers/extenders literally increase the overall "bulk" of the plastic.

Flame Retardants 

Function:
To prevent ignition or spread of flame in plastic material.  Plastics see substantial use in critical construction, electrical and transport applications which have to meet fire safety standards either by mandatory regulations or voluntary standards.  Flame retardants are added to plastics to meet these requirements.

Fragrances

Function:
Fragrances and deodorants for plastics are used in a variety of applications and arer products for the home.

Heat Stabilisers

Function:
To prevent decomposition of the polymer during processing. Processing usually results in temperatures well above 180 deg celsius, which without the addition of heat stabilisers would result in the plastic material literally falling apart

Impact Modifiers

Function:
Enables plastic products to absorb shocks and resist impact without cracking. Particularly relevant for polyvinyl chloride (PVC), polystyrene (PS) and polypropylene (PP) materials.

Internal Lubricants

Function:
Used to improve processability of plastics by increasing the flowability. Internal lubricants improve the melt flow of material by lowering the viscosity and heat dissipation (also see Processing Aids)

Light Stabilisers

Function:
Used to inhibit the reactions in plastics which cause undesirable chemical degradation from exposure to UV light.

Pigments

Function:
Tiny particles used to create a particular colour.

Plasticisers

Function:
Used to make plastics softer and more flexible.

Process Aids

Function:
Used to improve processability of plastics by increasing the flowability.  Internal lubricants improve the melt flow of material by lowering the viscosity and heat dissipation (Also see Internal Lubricants) High-polymeric processing aids also improve flowability of PVC compounds.

Reinforcements

Function:
Used to reinforce or improve tensile strength, flexural strength and stiffness of the material. Often fibre-based.