Expanded Polystyrene (EPS) is the generic industry name for the white rigid material made by expanding polystyrene beads with steam and pressure to bond the beads together to form blocks or to shape molds. 

Expanded Polystyrene (EPS) has the advantages of light weight, sound absorption, shock absorption, easy forming and low cost. It is one of the most widely used plastics in the world today. EPS is mainly used in household appliances, office machinery cushioning packaging materials, containers and disposable tableware. The mixture of n-Pentane and Isopentane can be used as foaming agent of EPS. Production of linear low density polyethylene pellets with isopentane as induced condensing agent.

EPS ( Expanded Polystyrene) or as many know by The Dow Chemical Company’s trademarked name, STYROFOAM, is an extremely lightweight product that is made of expanded polystyrene beads. Originally discovered by Eduard Simon in 1839 in Germany by accident, EPS foam is more than 95% air and only about 5% plastic.

Expanded Polystyrene (EPS): Production, Price, Market and its Properties

Expanded Polystyrene (EPS)

Expanded Polystyrene (EPS) is the generic industry name used for white rigid material made from the expanded polystyrene beads. It is a lightweight, rigid, plastic foam insulating material produced from solid beads of polystyrene.

The EPS beads are expanded and finally molded into larger EPS blocks which are further used for walls, roofs, floors, crawl spaces and architectural shapes.

It offers high R- Values for thermal insulation, flexibility in designing, dimensional stability, resistance towards moisture absorption and prevents physical degradation. It proves to be cost-effective and easy usage building material.

EPS is commonly used in form of a foam.  The word “styrofoam” is often used for the description of EPS foam. It is kind of trademark used of this foam material. Most common foam products used in daily lives include coolers, wine shippers, molded end caps and comers, packaging of boxes and even for the cups used at different places for water coolers.

How is Expanded Polystyrene made?

It is produced from styrene monomer. It is primarily a derivative of ethylene and benzene and is manufactured using a polymerization process which produces spherical beds of polystyrene. To assist the expansion of material usually low boiling point hydrocarbon (pentane gas) is added during the process.

It is produced in three stages

• Pre- Expansion- On contact with steam the pre-foaming agent present with polystyrene bead starts boiling and beads expand up to 40 to 50 times than their original volume.
• Conditioning- After the expansion process beads further undergo a maturing period to attain equilibrium of temperature and pressure.
• Moulding- Later, the beads are placed inside a mold and reheated with steam. The pre-foamed beads expand more to completely fill the mold cavity and fuse together.

Two molding processes used in producing EPS

• Black Moulding- It is used to produce large blocks of EPS which can further easily be cut and reshaped according to user demand. These blocks are used in both for packaging and construction applications.
• Shape Moulding- It is used to produce parts which require custom design specifications. Usually, this process is used for electronic product packaging where shape molded EPS are used largely.

Global Market Forecast of Expanded Polystyrene

The market for EPS is forecasted to grow more than US$ 18bn by 2022. The market was around US$16bn in 2016 and will cross US$ 17bn by 2020 as per the industry analysis. This market for EPS material has been growing rapidly since last few years and is also expected to increase in coming years also.

Market Segmentation

EPS market can be segmented on the basis of applications and material.

Based on Application:

• Packaging
• Construction
• Other Applications (slider, surfboards, houses and air conditioner units etc)

Based on Material:

• Raw beads
• Expanded Beads

Market Drivers

The market is primarily driven by growing construction and packaging industries in the developing nations. It is also widely being used in construction sector due to its suitable properties (lightweight, moisture retention, sound resistance, and durability etc).

Packaging has emerged as the major sector fueling the growth of market demand for EPS globally. As it has properties including shock resistance, keeping the consumable product fresh and maintaining their quality for longer time etc which are most suitable for packaging sector.

Increase usage of EPS in the pharmaceutical industry for storing products safely and preventing them from general environmental changes also help in the growth of its market demand.

Regional Outlook
The global demand for EPS material is divided into seven major regions including North America, Latin America, Asia Pacific, Western Europe, Eastern Europe, Japan and Middle East Africa.

Among these Asian Pacific regions have the major share in market demand due to emerging packaging industries in these regions which, is further followed by North America due to high demand for packaging of electronic goods.

Constraints
The market growth of EPS can be restrained by several factors such as volatility of crude oil prices and availability of high-performance alternatives such as Rockwool (extensively used as compared to EPS).

Key Market Players
The market of EPS is dominated by some major players including The Dow Chemical Company, Total S.A., BASF SE, ACH Foam Technologies Inc., Synbra Holding BV, Synthos S.A., SABIC, Kumho Petrochemical and Flint Hills Resources LLC.

Properties of Expanded Polystyrene
EPS is commonly preferred thermoplastic material for over half a century due to its performance, technical versatility, and cost-effectiveness. It is being widely used for the day to day applications. Its lightweight, strength, thermal insulation, durability and other properties make it suitable for a number of applications.

Basic properties of EPS
Lightweight- It is an extremely lightweight material as it comprises ~95% air. This property makes it a suitable material for packaging industry as it does not add weight to the product and reduces transportation cost.

Durability- The durability of this material makes it effective and reliable form of plastic used for packaging variety of goods. It is odorless and non-toxic in nature and the cellular structure makes it dimensionally more stable. This adds value to the product life.

Moisture Resistance- It is a closed kind of cell material and does not readily absorb water. EPS is an ideal material for cool-chain products as it does not loses its strength even in damp conditions. Hygiene requirement is easily met as the material is highly moisture resistant. It is also used for fishing floats and marina buoys due to this property.

Even if this material remains subjected to prolonged saturation in water it balances to maintain its size, shape, structure and physical appearance with a little amount of reduction in its thermal performance.

Shock Absorption- It offers an excellent form of shock absorbing property which results in making it the first choice of packaging material for number products including appliances, electronic products, computers, and chemicals.

Thermal Efficiency- The high thermal efficiency of EPS material is very helpful in the packaging of temperature sensitive products. Products stored in EPS containers have a longer life even at temperatures above or below ambient conditions. It also protects product even from the sudden change in temperatures and climate during transportation.

Example of temperature-sensitive products that require EPS containers are – seafood, fresh produce, pharmaceuticals, and variety of medical products

Versatility- It can be used to manufacture to almost any shape or size as it can be easily cut and shaped according to the requirement. It is also produced in a variety of densities with different physical properties according to the requirement of the product. Its compatibility with a large number of products also helps to increase its worth from other alternatives.

Ease of Use- EPS is regarded as the easiest material to be used especially in the construction industry. It is normally present in form of sheets which can be easily molded into shapes or large form blocks, as per the requirement.

Physical Properties

• Density, lb./cu.ft. – 0
• Compressive strength, p.s.i. –31-37
• Tensile strength, p.s.i. – 58-61
• Thermal resistance, R/in. – 2

Electrical Properties

The dielectric strength of EPS material is approximately 2KV/mm. At frequencies up to 400 MHz, the permittivity offered by the material is 1.02-1.04 with a loss factor which is less than 5×10-4 at 1MHz and less than 3×10-5 at 400 MHz.

The molded form of EPS can be treated with some anti-static agents to be used in electronic industries and military packaging.

Chemical Resistance

EPS is highly resistant to water and aqueous solutions of salts, acids, and alkalis. It is usually not compatible with organic solvents. UV radiation up to 120-140F has a slight effect on the molded form of material. It usually causes yellowing friability of the material but does not affect its physical properties.

Applications of Expanded Polystyrene

It is applicable to a variety of end-user markets in different forms. EPS is used to produce semi-finished and finished goods. The semi-finished materials produced from EPS are:

Expanded Polystyrene Foam Sheet

EPS materials on a very large scale are used to produce foam sheets globally. These sheets offer ease of use as they can be easily cut and molded or reshaped according to the requirement of usage.

EPS characteristics including lightweight ease of work, superior R-Value, strong moisture & water resistance etc prove its suitability, especially in the packaging sector.

EPS foam sheets are widely used in wall insulation, roofing, subfloors, medical product transportation and even for transporting perishable consumables.

Expanded Polystyrene Insulation

Today due to design-oriented goals of sustainability and energy efficiency, usage of insulation is gaining more importance than ever. There are different ways used to insulate a building. The most versatile three options available for rigid insulation are, EPS being used in roof, wall, floor, below grade and structural geo-foam applications.

EPS foam is the kind of insulation is used most widely in insulated concrete forms and structural insulated panels. EPS foams are cost-effective and also meet all required building and energy codes.

Pros and Cons of EPS Insulation

There are certain advantages and disadvantages associated with the usage of EPS insulation material which are:

Pros

• Long-term and provide stable R-Value.
• Prevent from mold or mildew growth.
• They can be easily recycled.
• EPS insulating materials can be placed below grade.
• They can also be used for inverted assemblies.

Cons

• Exposure to the sun can deteriorate the product.
• Solvent-based materials can cause severe damage.
• Temperature above 250 degrees of Fahrenheit can melt polystyrene.
• They are incompatible with certain kind of thermoplastics which may result in permanent degradation.
• It is flammable and requires proper placement.

EPS is commonly used over house wraps or with products that provide factory lamination options. The R-Value provided by these EPS insulation dose does not degrade easily. Polystyrene insulations are also being used in asphalt built-up roofing systems with certain provisions to protect insulation heat and solvent-based products.

Market Applications of EPS

EPS material used commonly in form of EPS sheets has a wide range of users in different end segment industries according to the requirements. Some prominent sectors using this form of polystyrene are as follows:

Packaging Applications

EPS is a dominating material in packaging industry applicable to a number of uses due to its favoring characteristics. Perishable products such as egg, meat, fish and poultry, even cold drinks and carry out meals use EPS packaging materials to keep product safe and fresh.

EPS material has been recognized as a major versatile cost-effective solution for food and goods packaging globally.

Building and Insulation Applications

EPS resins are one of the most commonly used materials in building and construction industry. The insulation foams are widely used in roofs, floors and closed cavity walls etc. Due to its excellent price and performance ratio nowadays it is also being used in pontoons and construction of roads.

These foams are also being used for civil engineering and in several building activities including void forming, drainage, impact sound insulation, cellular bricks, roads and as modular construction elements.

Other Applications

EPS materials are used for producing goods for a number of other applications. It is used in manufacturing products such as crash helmets (protecting heads and lives of the cyclist), surface and other decorations ranging from simple brand name printing to pictorial representations through mold engraving.

These materials are also used widely for producing goods related to fun and sports such as windsurfing board etc.

Recycling of Expanded Polystyrene

These polymers are completely recyclable. The processes involved in recycling of EPS include:

Segregation- EPS scrap is segregated from the bunch of plastic scraps. Usually, this segregation is done before it enters the waste stream to avoid any kind of contamination.

Collection-As EPS is a lightweight material transportation cost is a major factor in its recycling. The EPS scrap is either bagged in loose form or baled before transportation.

Reprocessing– The collected EPS is put into the granulation machine where it is compressed. The compressed plastic pellets are the recycled materials which are reused to produce new goods.

Uses- The recycled form of EPS can be further used as feedstock for the number of applications such as synthetic timber, CD, and DVD cassette cases, stationary products even as plant pots and other gardening products.

The blowing agent used since EPS Foam was first introduced in 1952 by BASF is Pentane gas which, does not contain any chlorine atoms as CFC’s. PSP Foam in the beginning used CFC’s as blowing agent. In the past two decades CFC’s are gradually phased out from plastics and refrigerator industries.

It is contemplated that various blowing agents may be used in the present invention, including physical blowing agents such as hydrocarbons. The preferred physical blowing agents for this invention are organic chemical compounds that have boiling points less than about 37° C. These organic compounds include, but are not limited to, fully hydrogenated hydrocarbons and partially fluorinated hydrocarbons that are considered to be flammable. Flammable as defined herein generally includes those materials having flashpoints less than about 37.8° C.

The preferred fully hydrogenated hydrocarbon blowing agents include the initial members of the alkane series of hydrocarbons that contain up to five carbon atoms and which are not regulated by governmental agencies as being specifically toxic to human or plant life under normal exposure. These fully hydrogenated blowing agents include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane and blends thereof.

The most preferred fully hydrogenated hydrocarbon blowing agents are C₂ to C₄ compounds and blends thereof An example of a preferred blend is a blend of approximately 67 weight percent n-butane and approximately 33 weight percent isobutane, which is commonly referred to in the industry as an A21 butane blend. This blend may be added at a rate of from about 1 to about 20 weight percent of the total extruder flow rate, and preferably added at a rate of from about 3 to about 20 weight percent of the total extruder flow rate.

It is contemplated that auxiliary blowing agents may be used in the present invention in amounts less than about 40 weight percent of the total blowing agent. The preferred auxiliary blowing agent are partially fluorinated hydrocarbon blowing agents that have molecules containing up to three carbon atoms without any other halogen atoms, and those considered flammable. For example, this includes 1,1-difluoroethane (HFC-152a), and 1,1,1-trifluoroethane (HFC-143a), with the most preferred auxiliary blowing agent being HFC-152a. It is also contemplated that 1-1-chlorofluoroethane (HFC-142b) and 1-1-dichloro-2-fluoroethane (HFC-141b) may be added as auxiliary blowing agents for non-regulated insulation applications.

In addition, water may optionally be added at a low concentration level as an auxiliary blowing agent. The water quality should be at least adequate for human consumption. Water containing a high level of dissolved ions may cause excessive nucleation, so therefore deionized water is preferred. The preferred rate for water addition is from about 0.05 to about 0.5 parts water to 100 parts of the polymeric composition (0.05 to 0.5 phr). The most preferred rate of adding water is from about 0.2 to about 0.3 phr.

What is EPS

Polystyrene is one of the most widely used kinds of plastic. It is a polymer made from the monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. Polystyrene is a thermoplastic substance, it melts if heated and becomes solid again when cool.

Polystyrene is most commonly found in three forms. Rigid Polystyrene (PS), Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS).

Rigid polystyrene has many applications including disposable cutlery, cd cases, video/casette casings, components for plastic model toys as well as some margarine and yoghurt containers.  Extruded polystyrene foam has good insulating properties making it important as a non-structural construction material.  XPS is sold under the trademark Styrofoam by Dow Chemical, however this term is often used informally for other foamed polystyrene products.

How to produce foam?

Expandable Polystyrene / EPS:

This is PS Foam that uses Pentane gas (C5H12) as the blowing agent. During the material production process called “Polymerisation” the polystyrene resin granules impregnated with the blowing agent. EPS production processes begin in the pre-expansion process where the EPS bead will expand by the heat of steam usually 50 times in volume. The next step in the process is moulding process where expanded foam bead will be heated again with steam then they expand further until they fuse together, forming as foam products.

There are mainly 2 types of EPS moulding machines;

• Shape moulding machine that produce various shapes of foam products according to the molds such as icebox, helmet and packaging foam.
• Block moulding machine that produce block foam and sheet foam Expanded EPS foam bead contains 98% air per volume, only 2% is plastic. This make EPS foam very light weight, has low thermal conductivity because air is the best insulation, high compressive strength and excellent shock absorption. These properties make EPS to be ideal material for packaging and construction.

Polystyrene Paper (PSP):

This is a PS Foam which is produced by extruding process as another plastic. Production process start when put polystyrene resin pellets into the extruder that heated by electric. Foaming process occur at the end of extruder where the blowing agent, butane (C4H10) gas react with the melt plastic then become foam. The melted polystyrene foam is then extended as sheet then rolled as paper roll, that is why it is commonly known as “Polystyrene Paper”. The polystyrene foam sheet or polystyrene paper can be produced as many shape according to the mould by thermal forming process such as food tray, cups, bow, and food box.

Both EPS and PSP contain 95 -98 % air another 2-5% is polystyrene which is pure hydrocarbon. CFC’s is Chlorofluorocarbons which is totally different in its chemical structure from polystyrene. CFC’s has very low blowing point and uneasy to be maintained in EPS beads. Therefore, EPS Foam never use CFC’s at any stage of its production. The blowing agent used since EPS Foam was first introduced in 1952 by BASF  is Pentane gas which, does not contain any chlorine atoms as CFC’s. PSP Foam in the beginning used CFC’s as blowing agent. In the past two decades CFC’s are gradually phased out from plastics and refrigerator industries. PSP moulders in Thailand already use Butane (C4H10) as the blowing agent since the last 15 years. Butane gas is the gas that we use at home for cooking. The blowing agents that use in producing PS Foam are Pentane and Butane, which are pure hydrocarbon as polystyrene. They belong to the same chemical family, the paraffin series as methane, ethane, and propane gas.

How to manage the EPS foam waste

Apart from recycling by melting and compacting, there are many ways to manage the EPS waste as the followings:

• Crush in to small particle and mix with soil. Foam waste will improve ventilation in the soil, organic substances in the soil will become easier the humus.
• Mixing the crushed bead with cement to reduce the weight and increase insulation properties.
• Combustion at 1000 C with sufficient air supplies in to generate heat. Burning EPS require no any additional fuel, in fact EPS can replace the fuel normally required for combustion, l kg of EPS saves 1 kg = 1.2 – 1.4 Litre of fuel oil.

The Recycling of PS:

Since both EPS and PSP Foam are made of Polystyrene, which is thermoplastic, so that it will become again a polystyrene plastic when recycled. AMEPS members recycle both EPS and PSP Foam by first crushing into small particle then melting or compacting it. Melting can be done by heated roller, disk or screw extruders, where the regrind scraps is heated usually by electrical power for some time above the melting temperature. Compacting can be done by rotary compactors where pressure and frictional force create heat below melting temperature to soften the regrind scraps for only few seconds. This method also called “agglomeration”.PS pallet from recycled foam will be produced in various kinds of plastic products e.g. video and tape cassette and ruler. The other way to reuse EPS Foam is to mix the regrind beads with the new expanded bead for re-production in moulding process.