What is Expanded Polystyrene

Polystyrene is one of the most commonly used kinds of plastic, where it is formed from monomer styrene, liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. Due to its thermoplastic substance, the polystyrene melts when it is heated and will solidify again once cooled.

There are many forms of polystyrene such as Extruded Polystyrene (XPS) and Expanded Polystyrene (EPS). Expanded Polystyrene is a lightweight cellular plastic material consisting of small hollow spherical balls, where the closed cellular structure gives EPS its remarkable characteristics. For example, once presented against a flame the EPS material melts away, and when flame is removed the material cools down and will solidify again once cooled.

Due to Expanded Polystyrene’s closed cellular structure it is able to produce a wide range of densities, providing a varying range of physical properties that are matched to various applications where the material is used to optimize its performance and strength.

History of Polystyrene:

Over the years the history of polystyrene has grown since 1939 when German apothecary Eduard Simon had first discovered polystyrene. Although it wasn’t till 80 years later that organic chemist Hermann Staudinger, realized that Simon’s discovery had comprised of long chains of styrene molecules, which creates a plastic polymer. In 1922 Herman Staudinger had published his theories of polymers and had won a Nobel Prize for Chemistry in his research in 1953. Although, back in 1953, the scientists at BASF developed a way to commercially manufacture polystyrene in pellet form, then in 1937, the Dow Chemical company introduced polystyrene products to the U.S. market. Then by 1951, BASF had developed a patented EPS known as styropor which has led to the creation of EPS which is now one of the most versatile and cost-effective materials for both packaging and building/ construction applications because of its benefits in product, performance and recycling.

How is Expanded Polystyrene Made?

Expanded polystyrene is manufactured from styrene monomer; where low levels of styrene monomer can be found naturally in plants, fruit, vegetables, nuts and meats. Expanded polystyrene is a derivative of ethylene and benzene and can be made by using a polymerization process which produced a translucent spherical bead process which produces a translucent spherical bead of polystyrene. The way Expanded Polystyrene is produced is by a three-step process:

Pre-Expansion:

Upon contact with the steam the pre-foaming agent found within the polystyrene beads start to boil and the beads are expanded between 40 – 50 times their original volume.

Conditioning:

After pre-expansion the beads undergo a maturing process period in order to reach a equilibrium temperature and process. Which will then lead to the molding process.

Moulding:

After the conditioning stage the beads undergo a maturing period in order to reach an equilibrium temperature and pressure, because the polystyrene is pre-foamed it allows the beads to expand further and completely fill the mould cavity and fuse the beads together. Most moulds are used to make polystyrene blocks which can be used to cut and create different shapes and sheets, which can be used in building, constructions, arts and crafts, packing and many more.

How is Expanded Polystyrene (EPS) recycled?

Polystyrene is recycled in four different stages; Segregation, Collection, Reprocessing and Export.

Segregation;

Segregation is where the polystyrene needs to be separated before it enters the mainstream to minimise contamination. For example, putting it into a separate bag from your normal garbage and plastics. This needs to happen so that the polystyrene doesn’t end up in landfill and can be recycled properly.

Collection

Due to Expanded Polystyrenes lightweight properties, it makes the costs for transportation a major component when recycling the polystyrene and transporting it between trucks to the persons designated recycling factory. When the polystyrene is getting collected the polystyrene scrap is either bagged in loose or baled form, it is also quite common in Australia for a lot of business to utilize a lot of expanded polystyrene packaging and have worked with recycling companied to assist with transportation and collection costs.

Reprocessing

Reprocessing is where the Expanded Polystyrene is fed into a granulation machine, where the granulated material is then fed to a hopper where it is stored before being compressed into continuous lengths. From there the material is then broken into lengths suitable for palletisation, where once palletised the materials are then ready to be exported.

Export

Export is where most of the Expanded Polystyrene is recycled for further reprocessing as there are such small quantities of EPS waste generated in Australia and very little domestic demand for the product.