What is EPS?
Expanded Polystyrene, or EPS for short, is an economical, versatile, lightweight, rigid, plastic foam insulation material produced from solid beads of polystyrene. The end product is made up of fine spherical cells that comprise 98% air.
EPS has a very high strength to weight ratio that, dependant on the density, offers exceptional compressive and flexural strength and dimensional stability characteristics. It can be moulded or shaped to meet almost any design requirement.
Who needs EPS?
Architects, civil engineers, marine engineers, builders, concreters, packaging companies, creative designers, et al;
Insulation, building applications (including cladding and concreting), road and bridge works, flotation, protective packaging, theming (creative works in theme parks and on buildings). Your imagination really is the limit.
National Polystyrene Systems (NPS) EPS range comprises block moulded and shape moulded expanded polystyrene products. NPS block foam is manufactured to AS1366 Part 3 ~ 1992 and contains a flame retardent.
The minimum physical properties specified in this standard are the minimum requirements to which NPS foam complies, however if physical properties outside this standard are required, a tailor made class of NPS foam can be designed to meet these requirements. The nominal densities used to manufacture expanded polystyrene are as listed in the standard; however the physical properties may be achieved using other densities, depending on raw material and other variables. The table below lists the minimum physical properties of NPS foam as it compares to AS1366 Part3 ~ 1992.Physical PropertyUnitClassTest method used to measure complianceLSLSMHVH
Average Densitykg/cum1113.516192428— Identification Colour per AS1366.3ColourBlueYellowBrownBlackGreenRed Compressive strength at 10% deformation (min).kPa507085105135165AS2498.3 Cross breaking strength (min).kPa95135165200260320AS2498.4 Rate of water vapour transmission (max) measured parallel to riseug/m2s710630580520460400AS2498.5 Dimensional stability (max)%111111AS2498.6 Thermal resistance (min) at 25 degree C.(50mm Sample)
Thermal Conductivity (min) at 0 degree C. (50mm Sample)m2K/W W/mK1 0.0391.13 0.0371.17 0.0361.20 0.0351.25 0.0341.28 0.032AS2464.5 or
median flame duration
eight value (max)
median volume retained
eight value (max)s
The density of NPS expanded polystyrene foam is low compared to water, with a nominal density range from 13 to 28 kg/m3 compared with water at 1000 kg/m3. The water buoyancy per cubic meter of NPS Foam is determined by subtracting its kg/m3 density from 1000. The result is the weight in kilograms, which a cubic meter of NPS Foam can support when fully submerged in water.
NPS expanded polystyrene foam is resistant to virtually all aqueous media, including diluted acids and alkalis. It is also resistant to water-miscible alcohol such as methanol, ethanol and I-Propanol, and also to silicone oils. NPS Foam has limited resistance to paraffin oil, vegetable oils, diesel fuel, and Vaseline. These substances may attack the surface of NPS Foam after long term contact. NPS Foam is not resistant to hydrocarbons, chlorinated hydrocarbons, ketones and esters. Paint containing thinners and solutions of synthetic adhesives fall into this category, and this should be taken into account in any painting or bonding operations. Anhydrous acids such as glacial acetic acid and fuming sulfuric acid destroy NPS Foam.
Resistance to Fungi and Bacteria
Fungus attack has not been observed on NPS expanded polystyrene foam and it does not support bacterial growth. Surface spoilage (in the form of spilt soft drink, sugar, etc) can however supply the nutrient for fungal or bacterial growth.
The heat of combustion of solid polystyrene polymer is 40,472 kJ/kg – Combustion products are carbon dioxide, water, soot (carbon), and to a lesser extent carbon monoxide.
A CSIRO report comments that the toxicity of gases associated with the burning of expanded polystyrene is no greater than that associated with timber. Toxicity of thermal decomposition products of EPS appears to be no greater than for wood and decidedly less than other conventional building products i.e.
Polystyrene CO=0.09 plus CO2=0.01 Total=0.10
White Pine CO=0.09 plus CO2=0.003 Total=0.09
Expanded polystyrene products are combustible and should not be exposed to open flame or other ignition sources. Insulation material, as with other organic material, must be considered combustible and to constitute a fire hazard if improperly used or installed.
Expanded polystyrene (F Grade) contains a fire retardant additive to inhibit accidental ignition from small fire sources.
Please refer to the table below for a comparison of expanded polystyrene with other common building materials.MaterialIgnitability Index (0-20)Spread of Flame Index (0-10)Heat Evolved Index (0-10)Smoke Produced Index (0-10)Expanded Polystyrene – with sizalation 450 facing0000 – 1Expanded Polystyrene – sandwich panel with 0.65mm steel0000Expanded Polystyrene12035Rigid Polyurethane181047Australian Hardboard – Bare146073Australian Hardboard – Impregnated with fire retardant (4.75mm)0007Australian Softboard – Bare16973Australian Softboard – Impregnated with fire retardant (12.7mm)4007T&G Boarding (25×100) – Bluegum11032T&G Boarding (25×100) – Oregon13653Plywood, Coachwood veneer (4.75mm) – Bare15774Plywood, Coachwood veneer (4.75mm) – Impregnated with fire retardant12035
Expanded Polystyrene and the environment
EPS offers substantial environmental advantages:
- EPS is safe, non-toxic and totally inert. At no time in its life cycle does it contain any Chlorofluorocarbons (CFCs) or Hydrochlorofluorocarbons (HCFCs). It is also absent of any nutritional value, so no fungi or micro-organisms, such as mould, can grow with EPS.
- EPS is recyclable: EPS can be recycled in many ways once it comes to the end of its life. These include recycling directly into new building products and incineration to recover its inherent energy content (waste to energy). The choice of a recycling method is based on technical, environmental and economic considerations.
- EPS presents no dangers to health in installation, during use and in the waste stage.
- EPS insulation saves money by reducing energy bills;
- EPS, as an effective insulation material prevents energy loss and therefore helps to conserve fossil fuels, prevents carbon dioxide emissions which cause the greenhouse effect and global warming.
Recent years have shown growing concern for the environment and in particular an increased demand for sustainable building and development. For the construction industry this means a need for accurate information about the environmental impact of the building materials and products that they use. Expanded polystyrene stacks up. The most reliable way to present this information has proven to be the Life Cycle Assessment (LCA) approach. This approach investigates the processes involved in the manufacture, use and disposal of a product or a system – from cradle to grave.
Expanded polystyrene insulation has a long lifetime in buildings and so there is only limited current need to recycle this material. However, since EPS does not degrade or deteriorate, it can be recycled in several ways at the end of its useful lifetime:
- Regranulated EPS can be reused in measured quantities in the production of selected products such as waffle pods and some block applications. The quantities used are dependent on the required technical performance.
- There are a number of non-foam applications. Recycled EPS can be moulded into new applications such as coat hangers, flower pots, park benches or fence posts.
- EPS waste can also be reground and mixed with concrete to produce building products such as prefabricated light weight concrete blocks. Adding EPS regrind also increases the thermal performance of these products.
Unlike the main competitive insulation materials, polystyrene is easily recycled. Not only does the EPS Industry recycle factory waste but also post consumer packaging waste is collected and processed by arrangement.
Recycling saves money, energy and reduces the impact on the environment. EPS is not seen as waste in most European countries but as a valuable resource. EPS is the most easily recycled of all the insulating materials and therefore most easy to align with the “cradle to cradle (C2C)” principle.
The EPS National Industry Group (EPSA) has established collection centres in each capital city of Australia.
EPS organisations from more than 25 countries around the world have signed the International Agreement on Re-cycling.
A process not yet commonly used in Australia, is “waste to energy”. Energy recovery is usually in the form of heat from the incineration of waste. The process gives materials, which cannot be recycled economically, a genuine postconsumer use. Energy recovery is a safe and environmentally sound means of generating real environmental and economical value from EPS used for fish boxes, horticultural trays or other contaminated EPS waste.
In a modern incinerator, EPS releases most of its energy as heat, aiding the burning of municipal solid waste and emitting only carbon-dioxide, water vapour and trace non-toxic ash. Pollution control equipment such as scrubbers and filters reduce pollutants released during the incineration process. EPS is safely burned at high temperatures in this process without giving off toxic or environmentally damaging fumes.
NPS manufacturing plants are operated in conformance with the stringent health and safety legislation and in consultation with employees and safety professionals.
There are 5 manufacturing stages:
Polystyrene granules are expanded by free exposure to steam to form larger beads, each consisting of a series of non-interconnecting cells.
2) Conditioning (Curing):
After expansion, the beads still contain small quantities of both condensed steam and pentane gas. As they cool, air gradually diffuses into the pores, replacing, in part, the other components.
The expanded polystyrene beads are moulded to form blocks or customised products. The mould serves to shape and form the pre-foam, and steam is again used to promote expansion. During moulding, the steam causes fusion of each bead to its neighbours, thus forming a homogeneous product.
4) Cutting and Shaping of Expanded Polystyrene Blocks:
Following a short cooling period, the moulded block is removed from the machine and after further conditioning, may be cut or shaped as required using hot wire elements or other appropriate techniques.
5) Post-production processing:
The finished product can be laminated with steel, foils, plastics, fibreboard or other facings to form many and varied building products.