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All About Polystyrene

What is polystyrene?  Polystyrene is a synthetic aromic polymer that is made from the monomer styrene, which is a liquid petrochemical.  It is also know to be a thermoplastic substance in which usually exists in a solid state at room temperature.  Typically it can be heated and melted for molding or extrusion purposes; eventually it will become a solid again once it has cooled off.

One thing you may not know is that polystyrene is one of the most widely used types of plastic.  A few other facts about polystyrene are that the solid form of it is hard plastic that has little to none flexibility.  Typically solid polystyrene also can be used to make molds with very fine detail in them. Another thing is that polystyrene can be transparent or have multiple different colors on it.  Some examples that polystyrene is used for are: disposable cutlery, plastic models, CD’s & DVD cases, and smoke detector housings.

Forms of Polystyrene

Additionally there are 3 different forms of polystyrene such as expanded polystyrene foam, extruded polystyrene, and extruded polystyrene foam. Every one of these forms of polystyrene have their own variety of applications. Also polystyrene can be used in polymer-bonded explosives. Density of expanded polystyrene is an important factor because it can range from 25 kg/m3 – 200 kg/m3 and depends on how much gas has been used to create the foam.  There are actually some popular products that are used from expanded polystyrene like surfboards, and the ever so famous Styrofoam cups, which happen to be used all over the world.  Styrofoam cups are most commonly used for fast food companies, usually located in the United States, Japan, Australia, and New Zealand.  An interesting fact about polystyrene Styrofoam cups is that you are able to put them through the dishwasher without getting deformed but only if it is set at 70° C because of the fact that is has a glass transformation temperature at 95° C. Expanded polystyrene cuts very easy with a hot wire foam cutter.  The hot foam cutter is simple and made by a heated taut length of wire.  Usually it is used from nichrome since nichrome is very resistant to such high temperatures, which is suitable for electrical conductivity. The way hot wire foam cutter works is by heating the wire to a certain temperature so that it melts the foam that is next to it right away. Therefore the foam will melt before it even has a chance to touch the wire causing smooth cuts from the hot foam wire cutter.

The polystyrene that is cut and shaped with foam cutters is used for a number of different things such as; architecture models, amusement parks, actual signage, movie sets, airplane construction, and so many other things.  These specific cutters can range from a few dollars to tens of thousands of dollars for much bigger CNC machines that are used for larger projects.  A traditional cutter can also be used to cut polystyrene, but for that to be possible and not ruin the blade I the process you need to dip the blade in water and cut at a 30° angle. It’s best if you repeat this process multiple times in a row. If you want good results.  There are also different types of unique polystyrene cutters that look more like cylinder rasps.

Extruded Polystyrene

Extruded polystyrene is completely different from expanded polystyrene, which is known as styrofoam. As for extruded polystyrene it is typically pretty flexible due to being filled with trapped air, also its low density and low thermal conductivity.  However some things extruded polystyrene is used for are packing peanuts and packing material for cushioning fragile items in boxes.  Another important fact about extruded polystyrene is that it can be used for its conduction material.  Considering its insulating properties make it important construction material. Extruded polystyrenes insulation helps its building structures such as ornamental structures. In addition to extruded polystyrenes other uses is lightweight fill for embankments in the civil engineering industry.

Even though extruded polystyrene is in the crafts models building, to be specific the architectural models.  Generally being foamed between two sheets of paper this will tend to make a positive substitute for cardboard, which has been given the name foamcore.

Disposal and Recycling

The Society of Plastics created a symbol known as the resin identification code for polystyrene because they wanted an easy way to label an item to be able to tell if it is recyclable or not.


Evidently the effects of polystyrene that has been incinerated at high temperatures can cause chemicals such as water carbon monoxide, some volatile compounds and carbon soothe to be generated.  For example one ton of foam cups will produce 0.2 ounces of ash, however you will produce about 200 pounds of ash per ton if you used paper cups.

If there is barley any oxygen or very low temperatures when burning polystyrene it will produce polycyclic aromatic compounds, carbon black and carbon monoxide, plus styrene monomers.


Polystyrene products such as foam cups and other products are suggested to be buried in landfills because it’s concrete and brick like stability.  There also is no need for plastic film to be used to protect the air as well as the underground water.


Typically as of right now a good percentage of polystyrene products are not being recycled basically because of the fact that there are not enough quality recycling facilities.  When recycling polystyrene it can be used to create park benches, flower pots, and toys. Although the initial process of “recycling” polystyrene may not be officially complete and is known to produce more polystyrene instead. With that being said polystyrene cups and other products used for packaging as an alternative option they are usually recycled into fillers in other plastics, or items that can’t be recycled are bound to be thrown in the trash.

Environmental Concerns and Bans

Polystyrene is very light weighted especially if it is foamed and has low scrap value therefore it is actually hard to recycle. Curbside collection recycling programs do not accept polystyrene to be recycled since pure polystyrene is very resistant to bio-degradation and photolysis. If wild animals ingest any form of plastic it may be very harmful to them. Plastic is now officially considered to be a component of marine debris said by the California Coastal Commission.