Physical and Chemical of Styrofoam Properties

What exactly is Styrofoam? What are the different Styrofoam properties? In this article, we shall learn about the physical and chemical properties of Styrofoam.

Styrofoam Properties | Styrofoam densifierStyrofoam, commonly known as ‘polystyrene’ is one of the most widely used type of plastics, is an inexpensive and hard plastic that use in a number of applications. The outside housing of computer, housings of most kitchen appliances, model cars and airplanes, toys, molded parts in cars are all made of Styrofoam. It is also made in the form of foam that is used for packaging and insulating.


Styrofoam is actually an aromatic polymer that is made from the monomer styrene. It is a long hydrocarbon chain that has a phenyl group attached to every carbon atom. Styrene is an aromatic monomer, commercially manufactured from petroleum. Styrofoam is a vinyl polymer, manufactured from the styrene monomer by free radical vinyl polymerization.

Styrofoam is a rigid, transparent thermoplastic, which is present in solid or glassy state at normal temperature. But, when heated above its glass transition temperature, it turns into a form that flows and can be easily used for molding and extrusion. It becomes solid again when it cools off. This property of Styrofoam is used for casting it into molds with fine detail. Pure Styrofoam polymer is colorless and hard with limited flexibility. It can be transparent or can be made to take on different colors.

Properties of Styrofoam

Styrofoam is hard and brittle and has a density of 1.050 g/cm³. It is represented by the chemical formula, C8H8. It is made up of three chemical elements, carbon, hydrogen and oxygen. Most of the Styrofoam properties are as a result of the unique properties of carbon. It is highly flammable and burns with an orange yellow flame, giving off soot, as a characteristic of all aromatic hydrocarbons. Styrofoam, on oxidation, produces only carbon dioxide and water vapor. The physical properties of polystyrene given below:

  • Density – 1.05 g/cc
  • Dielectric constant – 2.4 to 2.7
  • Thermal conductivity – 0.08 W/(m.K)
  • Young’s modulus – 3000 to 3600 Mpa
  • Tensile strength – 46 to 60 Mpa
  • Melting point – 240 ºC
  • Water absorption – 0.03 to 0.1

Styrofoam is chemically nonreactive and hence, used to make containers for other chemicals, solvents and even food items. The transformation of carbon-carbon double bonds into less reactive single bonds in Styrofoam, is the main reason for its chemical stability. Styrofoam is flexible and can be made into moldable solid or thick viscous solids. This is mainly because of the Van der Waal’s forces of attraction, that exist between the long hydrocarbon chains. However, when heat is applied, the chains can slide over each other. This property of intermolecular weakness along with the intramolecular strength, due to the strong hydrocarbon backbone, allows Styrofoam to be flexible and stretchable.

Styrofoam is soluble in solvents that contain acetone, such as most aerosol paint sprays and cyanoacrylate glues. Copolymers of polystyrene, that have improved properties, are made by adding other polymers with desired properties such as polybutadiene rubber, during the process of polymerization. Some examples of copolymers include high impact polystyrene and acrylonitrile butadiene styrene.

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