Expanded
Polystyrene
(EPS)
and the
Environment
Introduction
The impact on the environment of everyday materials is increasingly
important if we are to reduce our carbon footprint and protect our
natural heritage for future generations. Our aim, therefore, in this booklet
is to provide you with factual, well-documented information about the
environmental credentials of EPS.
EPS (expanded polystyrene) is an excellent material for packaging
and for construction as it is a light yet rigid foam with good thermal
insulation and high impact resistance.
This publication aims to provide balanced information based on the
manufacture, use and recovery from waste of EPS in the packaging and
construction sectors.
We also aim to demonstrate to customers, government organisations,
consumer associations and the public that, by choosing or using EPS,
you can be confident it is safe, complies with all relevant technical and
environmental standards and can easily be recycled at the end of its
primary use.
EXPANDED POLYSTYRENE (EPS) AND THE ENVIRONMENT PAGE 2
What is EPS?
Expanded Polystyrene (EPS) is a rigid cellular plastic, which is
found in a multitude of shapes and applications. It is used for fish
boxes, packaging for electrical consumer goods and for
insulation panels for building. These are the most commonly
known uses and we will mention others in this document.
XPS (extruded polystyrene) is also plastic foam based on
polystyrene that is formed by adding gas during extrusion not
by expanding beads containing gas; which is how EPS is formed.
A well-known use of XPS is the vac-formed polystyrene trays
used for small portions of food that we see in the supermarket.
Manufacturing Process:
We can see from the diagram that EPS is brought to us from the oil well through a chemical process. Now we will see what happens in the transformation that leads us to Expanded Polystyrene (EPS). The conversion of expandable polystyrene to expanded polystyrene is carried out in three stages.
1st stage Pre-expansion The raw material is heated in special machines called pre-expanders with steam at temperatures of between 80-100°C. The density of the material falls from some 630kg/m3 to values of between 10 and 35kg/m3 . During this process of preexpansion the raw material’s compact beads turn into cellular plastic beads with small closed cells that hold air in their interior. 2nd stage Intermediate Maturing and Stabilisation On cooling, the recently expanded particles from a vacuum in their interior and this must be compensated for by air diffusion. This process is carried out during the material’s intermediate maturing in aerated silos. The beads are dried at the same time. This is how the beads achieve greater mechanical elasticity and improve expansion capacity — very important in the following transformation stage. 3rd stage Expansion and Final Moulding During this stage, the stabilised pre-expanded beads are transported to moulds where they are again subjected to steam so that the beads bind together. In this way moulded shapes or large blocks are obtained (that are later sectioned to the required shape like boards, panels, cylinders etc).
The range of applications for expanded polystyrene is very wide. We are going to focus on these applications by putting them into three main categories and underline the properties that make EPS ideal for each one. The three categories are:
l Packaging
l Construction
l Other applications
Life Cycle Analysis
A life cycle analysis is a technique intended to quantify the total impact of a product during its production, distribution, use and recycling, treatment or disposal. As individuals, and as organisations, all our daily actions have an impact on the environment. We use energy and resources, generate emissions into the atmosphere, pollute water and produce waste. One of the tasks of a responsible business is to calculate its impact on the environment and to find ways to reduce it. However, some businesses use concern about the environment as a marketing tool and make claims that their products or materials are ‘environmentally-friendly’ or have a low carbon footprint. Responsible organisations will either conduct a thorough life-cycle analysis of a product, or calculate its carbon footprint using Carbon Trust methodology, (making their research public) before making statements of this kind Reliable life cycle analyses will measure: l Energy consumption l Air pollution l Water pollution l Global warming potential l Volume of solid waste CHEMICALS VEN
Overall, some 90% of all the derivatives of crude oil are transformed into energy in one form or another, as transportation fuel, for electricity generation and for heating. Only 4% is used as raw material for making plastics. Using oil to manufacture products in EPS can be an efficient use of this natural resource, for example: Each kilogram of oil used to produce EPS insulation panels creates a saving of 150kg of oil used for heating residences and buildings (calculated over a 50 year period). Using EPS to package a product will result in a reduction in fuel consumption compared to other materials. Questions about the effects of EPS on the Environment Pentane Pentane, a non-CFC expansion agent is used during the EPS production process to expand the polystyrene granules into a cellular structure. Pentane is a slightly volatile liquid that is continually formed in natural processes. For example, it appears in the digestive systems of animals and in the anaerobic decomposition of vegetable matter by micro-organisms. It belongs to the same chemical family as other better known gases like methane, ethane, propane and butane which are used as heating fuel. Pentane released during the EPS manufacturing process quickly turns into carbon dioxide and water in a photochemical reaction. It does not contain chlorine and so does not harm the ozone layer like CFCs or HCFCs. Although the pentane released during the production and transformation of EPS does contribute to man-made emissions of volatile organic compounds (VOCs) – these are only found in the 0-0.2% range Much greater quantities of methane are generated from the decomposition of human waste. Professor Hocking of the University of Victoria in Canada has recently shown that the methane released by decomposing standard size paper cups is 50 times higher than the quantity of pentane released in processing EPS cups. The EPS industry is researching new ways to reduce the levels of pentane used and to capturing and re-using pentane. Pentane is not considered to be a substance hazardous to health by European health authorities. The M anufacturing Process Steam is used as energy in the manufacturing of EPS. The steam itself is produced in boilers mainly using natural gas as fuel. Water consumption used in the manufacture of EPS is very low. The water is reused many times in the process. There is no solid waste generated during the EPS manufacturing process. Waste and off-cuts are easily put back into the production process. No material is wasted and clean used packaging can be recycled into new product using this method. There is no pollution to the surface or underground water supplies near an EPS plant because atmospheric and liquid emissions are very low during the manufacture of EPS. Questions about the effects of EPS on the Environment continued Styrene The monomer styrene, used in the manufacture of expandable polystyrene, has been manufactured for more than 60 years and is used for a wide range of plastics and plastic products. Styrene also exists naturally and can be found in many foodstuffs including strawberries, beans, nuts, beer, wine, coffee beans and cinnamon. Exhaustive research into the health effects of styrene has shown that although high exposure levels can be dangerous, like most chemical products, styrene is perfectly safe for normal use. Based on the current EU classifications and the current draft of the UK’s risk assessment report, styrene monomer is considered to have low oral toxicity, and is not classified in terms of carcinogenicity or mutagenic.
Manufacturing Process:
We can see from the diagram that EPS is brought to us from the oil well through a chemical process. Now we will see what happens in the transformation that leads us to Expanded Polystyrene (EPS). The conversion of expandable polystyrene to expanded polystyrene is carried out in three stages.
1st stage Pre-expansion The raw material is heated in special machines called pre-expanders with steam at temperatures of between 80-100°C. The density of the material falls from some 630kg/m3 to values of between 10 and 35kg/m3 . During this process of preexpansion the raw material’s compact beads turn into cellular plastic beads with small closed cells that hold air in their interior. 2nd stage Intermediate Maturing and Stabilisation On cooling, the recently expanded particles from a vacuum in their interior and this must be compensated for by air diffusion. This process is carried out during the material’s intermediate maturing in aerated silos. The beads are dried at the same time. This is how the beads achieve greater mechanical elasticity and improve expansion capacity — very important in the following transformation stage. 3rd stage Expansion and Final Moulding During this stage, the stabilised pre-expanded beads are transported to moulds where they are again subjected to steam so that the beads bind together. In this way moulded shapes or large blocks are obtained (that are later sectioned to the required shape like boards, panels, cylinders etc).
The range of applications for expanded polystyrene is very wide. We are going to focus on these applications by putting them into three main categories and underline the properties that make EPS ideal for each one. The three categories are:
l Packaging
l Construction
l Other applications
Life Cycle Analysis
A life cycle analysis is a technique intended to quantify the total impact of a product during its production, distribution, use and recycling, treatment or disposal. As individuals, and as organisations, all our daily actions have an impact on the environment. We use energy and resources, generate emissions into the atmosphere, pollute water and produce waste. One of the tasks of a responsible business is to calculate its impact on the environment and to find ways to reduce it. However, some businesses use concern about the environment as a marketing tool and make claims that their products or materials are ‘environmentally-friendly’ or have a low carbon footprint. Responsible organisations will either conduct a thorough life-cycle analysis of a product, or calculate its carbon footprint using Carbon Trust methodology, (making their research public) before making statements of this kind Reliable life cycle analyses will measure: l Energy consumption l Air pollution l Water pollution l Global warming potential l Volume of solid waste CHEMICALS VEN
Overall, some 90% of all the derivatives of crude oil are transformed into energy in one form or another, as transportation fuel, for electricity generation and for heating. Only 4% is used as raw material for making plastics. Using oil to manufacture products in EPS can be an efficient use of this natural resource, for example: Each kilogram of oil used to produce EPS insulation panels creates a saving of 150kg of oil used for heating residences and buildings (calculated over a 50 year period). Using EPS to package a product will result in a reduction in fuel consumption compared to other materials. Questions about the effects of EPS on the Environment Pentane Pentane, a non-CFC expansion agent is used during the EPS production process to expand the polystyrene granules into a cellular structure. Pentane is a slightly volatile liquid that is continually formed in natural processes. For example, it appears in the digestive systems of animals and in the anaerobic decomposition of vegetable matter by micro-organisms. It belongs to the same chemical family as other better known gases like methane, ethane, propane and butane which are used as heating fuel. Pentane released during the EPS manufacturing process quickly turns into carbon dioxide and water in a photochemical reaction. It does not contain chlorine and so does not harm the ozone layer like CFCs or HCFCs. Although the pentane released during the production and transformation of EPS does contribute to man-made emissions of volatile organic compounds (VOCs) – these are only found in the 0-0.2% range Much greater quantities of methane are generated from the decomposition of human waste. Professor Hocking of the University of Victoria in Canada has recently shown that the methane released by decomposing standard size paper cups is 50 times higher than the quantity of pentane released in processing EPS cups. The EPS industry is researching new ways to reduce the levels of pentane used and to capturing and re-using pentane. Pentane is not considered to be a substance hazardous to health by European health authorities. The M anufacturing Process Steam is used as energy in the manufacturing of EPS. The steam itself is produced in boilers mainly using natural gas as fuel. Water consumption used in the manufacture of EPS is very low. The water is reused many times in the process. There is no solid waste generated during the EPS manufacturing process. Waste and off-cuts are easily put back into the production process. No material is wasted and clean used packaging can be recycled into new product using this method. There is no pollution to the surface or underground water supplies near an EPS plant because atmospheric and liquid emissions are very low during the manufacture of EPS. Questions about the effects of EPS on the Environment continued Styrene The monomer styrene, used in the manufacture of expandable polystyrene, has been manufactured for more than 60 years and is used for a wide range of plastics and plastic products. Styrene also exists naturally and can be found in many foodstuffs including strawberries, beans, nuts, beer, wine, coffee beans and cinnamon. Exhaustive research into the health effects of styrene has shown that although high exposure levels can be dangerous, like most chemical products, styrene is perfectly safe for normal use. Based on the current EU classifications and the current draft of the UK’s risk assessment report, styrene monomer is considered to have low oral toxicity, and is not classified in terms of carcinogenicity or mutagenic.
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