Plastics Additives

Making things out of plastics is like playing a game with molecules. The aim is to re-organize them into new shapes without their changing color, sticking to the mold, or doing anything that could spoil the finished article. Additives help with all these problems. Below is a list of common used additives in injection molding.

Antistatic Agents: 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.

Blowing Agents: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: 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: 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: 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. 

Heat Stabilizers: 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: 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: 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.

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

Plasticizers: Used to make plastics softer and more flexible.

Reinforcements: Used to reinforce or improve tensile strength, flexural strength and stiffness of the material, often fiber-based.