Seven Important Things You Should Know About Polystyrene
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.
Seven important things you should know about Polystyrene
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How is Polystyrene made?
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.
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Polystyrene advantages and disadvantages
Pros of Polystyrene:
- Rigid with great dimensional stability.
- It is cheap and volume-commodity plastic.
- Good electrical insulator
- Good optical clarity
- Low dielectric loss.
- Transparent and colorless.
- It can be molded easily.
- Resistant to several diluted alkalis and acids
- Gamma resistant
Cons of Polystyrene
- Not a good resistor of UV rays and chemicals like hydrocarbons.
- Brittle
- Flammable
- The upper-temperature limit is low.
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Polystyrene is safe for making food packaging items.
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:
- The material
- Its cumulative exposure, and
- Safety levels of the exposure.
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.
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Advantages of using Polystyrene in manufacturing food packaging products
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.
- Helps lessen food-borne illness chances, which is why the packaging material is highly recommended for use in hospitals, schools, cafeterias, restaurants, nursing homes, homes, etc.
- With its insulation property, hot food stays hot and cold food remains cold. In other words, polystyrene packaging is the best to keep fresh food fresh.
- The cheap price of polystyrene packaging makes it an instant choice for the foodservice industry. The wholesale Polystyrene rates can be as much as five times less than other alternatives, like paper-based packaging, etc.
- Manufacturing EPS cups, containers, and plates are much more sustainable than manufacturing other corn or paper-based alternatives. It is because Polystyrene is lightweight, with EPS being 95% air.
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Other uses of Polystyrene
Besides the food packaging industry, Polystyrene is widely used for making other product types too. These include:
- Making electrical and electronic appliances like fridges, ovens, air conditioners, refrigerators, vacuum cleaners, microwaves, mixies, blenders, washing machines, computers, TVs, IT equipment, etc. The outer body is made of Polystyrene because of its inert nature.
- It is used in making different parts of cars and automobiles like the knob, door panels, sound dampeners, child seats, panels, etc.
- PS is used as an insulating material in roofs and walls of buildings, industrial storage facilities, freezers, etc.
- Used in manufacturing medical devices like test tubes, diagnostic components, culture trays, etc.
- It is used to make foam packaging products like egg cartons, poultry, meat trays, shipping cartons, etc.
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When was Polystyrene invented?
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.
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How are polystyrene products formed?
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.
