Is Styrofoam An Insulator? 5 Facts You Should Know !

Styrofoam is white-colored expanded polystyrene foam that is used as cushioning material for packaging. Now, let us discuss about insulating nature of Styrofoam.

Styrofoam is an insulator as it fulfills the basic requirement of an insulator by trapping electric current and heat inside and not transferring them. Styrofoam restricts the flow of charges, which is considered an electrical insulator.

Styrofoam resembles the properties of plastic, consisting of a pore-like microstructure that plays a vital role in providing insulator properties. Then in this post, let us discuss about three types of insulator behavior such as electrical, thermal and acoustic insulators exhibited by Styrofoam.

Why is Styrofoam a good electric insulator?

A good electrical insulator does not allow any charges or current transfer through them. Let us find the reason behind the good electrical insulation of Styrofoam.

Styrofoam is a good electric insulator because the benzene ring of Styrofoam does not contain any free delocalized electrons. Thus there is no discharge of electrostatic charges in the microstructure, so no motion of the electron is possible within the structure, so it is considered as a good electrical insulator.

Some types of Styrofoam allow electrical conductivity by carrying static electricity. This kind of Styrofoam is very rare.

Is Styrofoam a good heat insulator?

A material that does allow heat to escape from its core is considered as a good heat insulator. Let us check whether Styrofoam allows heat to escape from it or not.

Styrofoam is a good heat insulator. The microstructure of Styrofoam consists of many tiny air bubbles, so the heat is trapped inside those bubbles, so they can’t escape. The circulation of heat through the conventional method is also not possible in Styrofoam; thus, Styrofoam is a good thermal insulator.

Styrofoam consists mostly 95-98% of air which itself a good heat insulator.

Why is Styrofoam an acoustic insulator?

An acoustic insulator does not allow the transmission of sound or noise. Let us reason out why sound does not transmit in Styrofoam.

Styrofoam is an acoustic insulator because it does not allow transmission of sound waves out due to the presence of air bubbles that blocks sound wave. The transmission of sound waves take place due to the vibration of molecules in air. As a result of trapping the vibration , transmission is not possible in Styrofoam.

Image: Styrofoam balls by Saurabh R. Patil, (CC BY-SA 3.0)

Uses of Styrofoam as an insulator

Styrofoam is lightweight, buoyant and available at a reasonable price, so it has a wide range of applications. Let us list some uses of Styrofoam as an insulator.

  • Coffee cups and food containers make use of Styrofoam for trapping heat and keeping the food hot.
  • The ceiling and floor house of the cold region is fitted with Styrofoam board to keep the house warm.
  • The walls of some private buildings are made with a layer of Styrofoam as it is a good acoustic insulator.

Refrigerators, freezers and industrial cold storage make use of Styrofoam. Styrofoam is used under the road to prevent soil disturbance due to freezing and thawing.


Let us end this post by stating the good insulation of Styrofoam is due maximum air bubbles present in the structure. Styrofoam is the most used heat insulator because it is cheap and durable. Styrofoam is good sterilizer as well; hence it has a wide range of applications in the medical industry also.

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