The Isolite brand has grown rapidly from start-up to the leading EPS brand in Africa. Isolite manufactures and markets EPS and EPP to users of thermal insulation, packaging, semi-rigid cushioning, and specialised shape-moulded products. The Isowall Group has Isolite facilities in Gauteng, Kwazulu-Natal and Tema, Ghana; equipped with state of the art machinery – serving thousands of customers annually.
HOW ITS MADE
Literally translated, polystyrene is “polymerised styrene”. The expandable form (known as EPS) is initially produced as small beads containing a blowing agent. The beads expand when treated with steam, forming a lightweight “prefoam” of the required density.
These prefoamed beads are then processed in a mould to form large blocks (block moulded) that are then cut into sheets or other shapes. Alternatively, for high volume products, the beads are moulded into their final product form in individual moulds (shape moulded).
Resistant to: brine, fresh water, weak mineral acids, strong mineral acids (except concentrated nitric), weak alkalis, strong alkalis, most vegetable oils. Non-resistant to: mineral oils, chlorinated hydrocarbons, petrol, benzene, esters and ketones.
EPS is a combustible material. The amount of heat liberated by EPS undergoing combustion is very small and if this is dissipated then sustained ignition is unlikely. The ‘FR’ grades are treated with a fire retardant which causes the material to shrink away from a source of ignition without burning if exposed for a short period, but burns if kept in contact with the flame for a longer period.
FLAME RETARDANT GRADE (FR)
Flame retardant polystyrene (FR Grade) is available in all densities. Surface fire index results according to SABS 0177, part III yield the following results:
• Spread of flame index 4,4 • Heat contribution index 0,9 • Smoke emission index 9,9 • Surface fire index 4,7 • Class 5.
Material Properties of EPS
The below figures are for design purposes only. Actual values vary slightly with material supplier used.
|Property||Unit||15DV | SD||20DV | HD||30DV | EHD|
|K value Thermal conductivity||W/m.K||0,040||0,038||0,036|
|Water-Vapour Diffusion Resistance Value||–||20||30||60|
|Compression strength at 10% deformation||kPa||60||100||165|
|Short term compression strength||kPa||80||120||210|
|Long term compression strength||kPa||20||30||50|
|Water absorption fully-submerged after 7 days||% volume||1,7||0,6||0,5|
|Water absorption fully-submerged after 1 year||% volume||5,0||4,0||3,0|
|Linear expansion co-efficient||M/m||7.10-5||7.10-5||7.10-5|
|Co-efficient of friction||0,5||0,5||0,5|
|Heat capacity||J/kg K||1500||1500||1500|
|Limited exposure maximum temperature||°C||110||110||110|
Versatility of EPS
EPS has excellent thermal properties and is used in applications such as cold rooms, deep freeze facilities, refrigeration, fermentation tanks, vessels and for pipe and duct lagging.
The purpose of packaging is to protect goods on their way from the manufacturer to the consumer. Due to its excellent cushioning properties, heat resistance and limitless design possibilities, EPS is used for protective packaging in a variety of industries such as industrial, pharmaceutical, retail etc.
EPS is particularly suitable for fresh food packaging and transportation since it is shock resistant, non-toxic, odourless and does not attract insects or bacteria.
ART & DISPLAY
EPS is also used for publicity and sales promotion packaging, as many different decorative effects are easily achieved. EPS is easily painted using acrylic PVA applied by either spray or brush, and is easily cut and worked using conventional hand tools
In the construction business, EPS sheets and boards are used for thermal and sound insulation in walls, roofs and on floors, while loose beads are used as an aggregate in lightweight concrete, plasters and renderings. Other uses include under floor heating systems, drainage boards, permanent formwork, foundation and prefabricated wall systems.
Since EPS remains unaffected by micro-organisms in soil, it is ideal for geothermic insulation beneath roads, around foundations and in embankments where it prevents soil break-up through freezing.
Because of its strength, shock-absorbing properties as well as its versatility, EPS is also used for a variety of recreational applications such as bicycle helmets and surf-boards.
EPS and the Environment
A most important feature of EPS with regard to environmental impact is that expanded polystyrene can be recycled in a number of ways.
Pure EPS scrap can, for example, be ground down and used for the production of new EPS, mixed with soil as a composting aid or used as a lightweight aggregate for concrete and insulating mortars.
The EPS scrap can also be melted in an extruder and then used as a solid polystyrene feedstock in other plastic processing industries. For example, EPS is currently being recycled for the production of picture frames, dado rails and skirting boards. We make Isowood Skirting Boards and Dado Rails from all our EPS scrap.
Waste EPS, on the other hand, can be applied in feedstock recycling where it is used as a chemical source in the production of other materials, such as crude carbon for the manufacturing of steel. It can also be broken down, mixed with refuse and either burnt as a fuel or disposed of by landfill where it promotes aeration and the breakdown of organic matter