Specific Weight of Polystyrene and Its Functional Properties

Polystyrene is produced by polymerizing styrene — hence the name of the final product. Styrene, as the forming base of polystyrene, is a colorless liquid that is insoluble in water and soluble only in alcohol and ether solutions. The advantages of this type of plastic include absolute water resistance, significant resistance to chemical agents and transparency.

Polystyrene is produced by several methods:

• Polymerization of pure monomers (block-forming method).
• Polymerization in solvents.
• Polymerization in an aqueous emulsion.

Thanks to its unique properties, polystyrene can be processed. The most popular method is injection molding, which takes place under pressure. Powdered and granulated polystyrene are used in this process.

It is widely used for construction purposes. Most often it is used as:

• Colored facing tiles for rooms with high humidity and a high degree of contamination
• Porous tiles for heat and sound insulation
• Latex paint for interior finishing
• Films for moisture insulation
• Due to its high light-transmission capacity, polystyrene is well suited as a substitute for glass

Functional properties of polystyrene.

Depending on the production method, block and emulsion types of polystyrene are distinguished. Under normal temperature conditions, polystyrenes have an elastic form. The specific weight of polystyrene is 1.05 g/cm³, while the specific weight of styrene — the raw component — is only 0.909 g/cm³.

Using this value, the weight of 1 m³ of polystyrene can be calculated: for dense polystyrene it is about 1050 kg. When heated to roughly 90–100 °C, polystyrene softens and becomes more pliable; this is related to the material's glass transition rather than ordinary melting. Its ability to transmit light is very high — up to 90% of sunlight. Ether, aromatic and some hydrocarbon solvents can damage or dissolve polystyrene, so solvent compatibility should be checked separately. A significant difference between polystyrenes produced by different methods is the molecular mass of polystyrene:

• Block polystyrene — molecular mass 300000–500000.
• When an aqueous emulsion is used — 70000–200000.

This indicator is of significant importance during use. Polystyrenes with a low molecular mass will be brittle and weak. When purchasing, it is important to pay attention to this indicator: for a strong and durable construction material, it should be at least 100000.

Methods of polystyrene production.

The continuous block-forming method and the aqueous emulsion method are used most often. In the first method, styrene is poured into heated molds and compacted, forming a transparent and solid material. The final material has the ability to take the shape of the container in which the curing process took place. Most often, elongated rectangular molds — blocks — are used as the container. With this production method, polystyrene obtains a significant molecular mass, unlike with other methods. This effect is possible due to the use of low temperatures when heating the raw material — from 30 to 40 °C.

In other methods of polystyrene production, the temperature may vary between 60 and 90 °C. In addition, an initiator — benzoyl peroxide — is added to the raw material, which can accelerate the curing process. Unfortunately, this method has a significant drawback: the possibility of cracks forming in the polystyrene.

The method of producing polystyrene by means of an aqueous emulsion has advantages:

• The final product forms as a fine powder
• The production process takes a short period of time
• After the production processes are completed, polystyrene contains no monomers