Moulding Expanded Polystyrene (EPS)
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This page is kindly sponsored by the member companies of the BPF EPS Group |
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Overview
Expanded polystyrene (EPS) is used for the production of a number of applications. However its major application is as a protective packaging for consumer electronic products and white goods. Its excellent thermal insulation and mechanical protection properties make it ideal to package fish and other foodstuffs. EPS also has applications in horticulture as seed trays.
The outstanding shock absorbency of expanded polystyrene packaging ensures the protection of a broad range of products. Moreover, its compression resistance means that EPS is ideal for stackable packaging goods. When safety is paramount, EPS comes into its own. It is used in the manufacture of children's car seats and cycling helmets, where its protective qualities, strength and shock-absorbency are vital.
- Properties
- The Production and Moulding Process
- The Machines and Tools
- EPS and the Environment
- Sustainability of EPS
- About the BPF Expanded Polystyrene Packaging Group
- Find a Supplier of Expanded Polystyrene
Properties
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Durable
The exceptional durability means that it can effectively protect a wide range of goods. There is no loss of strength in damp conditions, making EPS ideal for cool-chain food products. The fact that the material is moisture resistant also means that the highest hygiene requirements are met. |
EPS White Goods Packaging
 EPS Horticulture Trays
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| Lightweight EPS is made up of 98% air. Due to its extremely low weight, its use as a packaging material minimises the total product weight. This reduces transportation costs compared with other packaging materials. In turn this means that transport fuel consumption is improved and vehicle emissions are minimised. All contributing to lower global warming. |
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| Insulating The thermal insulation properties help keep food fresh through the distribution chain. It is widely used to package fish and for seed trays where low heat loss assists in the growth of the plants. |
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Resistant The closed cell structure of EPS make it moisture resistant. In construction applications such as external wall insulation, it can be installed in all weathers, unlike some other insulation products; it can be used in flood risk zones with minimal risk and on flat roof applications for insulation. EPS boxes can be used for transporting fish with ice in the box and for medical items such as organs and vaccines. If stored in damp areas, there will be no impact on the products packed inside the EPS. |
 EPS Fish Boxes |
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Protective EPS is an effective shock absorber, is used for child car seats and bicycle helmets to protect against accidental blows to the human body. It is also used to protect high value items such as large screen TVs and other potentially fragile items in transit, reducing the waste of broken or damaged items and the need to replace and re-transport and re-package avoiding additional production and waste of energy and materials. |
 EPS Medial Phials |
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Stable and Inert The stable character of EPS is one of the key features that contribute to the sustainability of EPS products. EPS does not emit gases or leach chemicals into our water systems, it remains inert in all circumstances. This makes it safe for food packaging and for use on construction sites. |
 EPS Insulation |
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Density Unlike other thermoplastic processes, the production of EPS products requires that the raw materials be pre-conditioned prior to their final "tooled" moulding process. The raw material (also known as "expandable polystyrene" or "bead") has a sperical shape and is similar to sugar in appearance. |
EPS Beads |
The Production and Moulding Process
A unique factor of EPS is that it can be moulded to a very low density and a very high density. This gives it a wide range of applications in construction and it can be engineered to perform to different requirements. In packaging, it is often bespoke designed to provide specific protection exactly where it is required. This reduces the over-use of materials.
The conversion process is carried out in three stages:
| Pre-expansion The tiny spherical polystyrene beads are expanded to about 40 times their original size using a small quantity of pentane (typically 5% by weight) as a blowing agent. This process involves the heating of beads, using a flow of steam, which causes the blowing agent to boil and thus a honeycomb of closed cells is formed. |
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| Maturing As the material cools the pentane liquefies and a partial vacuum is formed inside the bead. The beads are returned to a holding tank for approximately twelve hours to allow the pressure differential to equalize, giving a stabilised granule. |
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| Final Forming In this final stage the pre-expanded stabilized beads are reheated with steam in a mould. The final expansion takes place and the beads coalesce to give a shaped moulding. This can also be used to form large blocks which can be sectioned to the required shape as panels, boards, cylinders etc. In this final form the EPS is made up of 98% air. |
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The Machines and Tools
The mould tool is fitted into a press, which has the facility to introduce steam from behind each half of the tool. The steam is introduced through small slotted vents, which have been machined into the mould tool when it was manufactured.
EPS and the Environment
Sustainability of EPS
EPS is 100% recyclable and widely recycled with thousands of tonnes recycled every year from the UK. Data from 2023 showed 66% of EPS packaging disposed of in the UK was recycled (EPS Group, 2023 - calculated by collecting raw data from UK convertors alongside UK and EU recyclers of EPS. Raw data and estimates have been used by industry experts to calculate the total recycling rate.). Alongside this, EPS is currently recycled in at least 38 countries over four continents. Recent reports by Conversio and the European Commission’s Joint Research Centre (JRC) highlight the remarkable progress achieved. Mechanical recycling is the most common method to recycle EPS whereas an emerging chemical recycling industry in the UK provide further opportunities.
To drive recycling rates further the EPS Group recently announced the launch of our EPS Recyclers Map, making it easier than ever to locate facilities that recycle Expanded Polystyrene (EPS). Whether you’re a business, organisation or local authority, the map provides you with easy-to-navigate features to find drop-off locations and contact details. It is a step forward in reducing waste and promoting a circular economy. This tool is here to support your recycling efforts.
Click HERE to find out more.
About the BPF Expanded Polystyrene Packaging Group
An objective of the Group is to raise awareness about the excellent combination of protection, cost-effectiveness and environmental performance that EPS can offer. Another objective is to increase the recycling of EPS and to promote awareness of existing recycling schemes. Click HERE for more information on the EPS Group.
Find a Supplier of Expanded Polystyrene
