Polystyrene or PS is a thermoplastic that is amorphous, hard, solid, colorless, transparent, brittle, rigid, resistant to gamma radiation, and non-polar. It is also an excellent electrical insulator because of air bubbles inside but is not high on resistance to ultra-violet rays and chemicals.
PS is a volume-commodity plastic material and has wide applicability. PS can be used for making semi-finished products like foams, sheets, and films. It is also used for making laboratory ware and food packaging items. It is used for making appliances, automobile parts, gardening pots, toys, equipment of different types, electronic items, toys, and more. The general method is to add different colorants and additives to the PS for manufacturing these items. Of the total thermoplastic market, Polystyrene makes for about 7% of the total market.
Polystyrene is made by polymerizing Styrene; that is why the name ‘Polystyrene.’ Styrene is a naturally-occurring chemical found in certain food items like coffee and cinnamon strawberries and even found in beef.
Polystyrene can be made into Expanded Polystyrene or EPS and extruded Polystyrene or XPS. These are foam materials known for their high cushioning and insulating properties.
EPS is made of 98% air, so it is extensively used in making packaging and insulation materials. It is also lightweight. These features make EPS makes it the number one choice for making protective packaging, insulation for appliances, automobile parts, used in roadways materials, and more.
Pros of Polystyrene:
Cons of Polystyrene
Polystyrene is widely used in making packaging materials, especially food packaging. Some examples include the cups for beverages. The Food and Drug Administration (FDA) in the US is the regulatory body for all kinds of food packaging materials.
The reason is that small particle from food packaging can migrate into the food. Therefore, FDA needs to keep a close watch over food packaging items. FDA evaluates every food packaging material on three parameters:
FDA has evaluated Polystyrene extensively as Styrene particles can remain even after manufacturing. That is why FDA has evaluated both, Polystyrene which is the food contact material, and Styrene that is the substance that can migrate into the food item. After extensive evaluation, the FDA has summarized its findings and says that Polystyrene is safe to be used as a food packaging material and can contact food without harming it.
Styrene’s acceptable intake level per person per day is about 90,000 micrograms, whereas, with polystyrene products, the daily intake level is about 6.6 micrograms.
FDA had approved and certified Polystyrene to be safe for use as a food packaging material a long time back. The European Commission as well the European Food Safety Authority have also approved Polystyrene for food packaging material.
Here are the advantages of using Polystyrene food packaging materials.
Besides the food packaging industry, Polystyrene is widely used for making other product types too. These include:
PS was discovered some 200 years back by Eduard Simon in 1839. He was an apothecary who accidentally discovered PS when isolating it from a natural resin. Later in 1922, scientist Hermann Staudinger studied PS to discover that it consisted of long chains of Styrene molecules. Staudinger was awarded the Nobel Prize for Chemistry in 1953 for this research. During the same time, Ray McIntire, an engineer At Dow Chemical Company, invented foamed Polystyrene or Styrofoam.
Spherical beads of Polystyrene get heated with steam. The beads contain an expanding agent or hydrocarbons. As the hydrocarbon boils, the beads start to expand and become forty times their original size.
These beads are now left to cool. They are then heated again. Now when the beads expand, they are made to do so within specific shapes and sizes of molds. It is when the molds can be given different shapes like cartons, plates, cups, etc.
The beads fill the molds completely and then get fused. Due to the expansion, the EPS or Styrofoam is filled with 98% air.