What is polystyrene?

Polystyrene, abbreviated PS, is one of the most widely used thermoplastics globally and plays a central role in both the packaging industry and technical applications. The material is a polymer that in its basic form is glass-clear, rigid and has excellent dimensional stability. Thanks to its combination of good insulation properties and high cost-effectiveness, polystyrene is a first choice for applications where precision and economy need to go hand in hand.

What is polystyrene made of?

Polystyrene is produced by the polymerization of styrene monomers. In industry, the material is mainly divided into two categories based on its molecular structure and additives:

  1. GPPS (General Purpose Polystyrene): Also known as ”standard polystyrene”. This is a glass-clear, hard, and brittle plastic with a high gloss.
  2. HIPS (High Impact Polystyrene): An impact-resistant variant where rubber (polybutadiene) has been added during polymerisation. This results in a material that is significantly more resistant to mechanical impact but becomes opaque (non-transparent).

The choice between GPPS and HIPS is entirely governed by whether the application requires optical clarity or mechanical toughness.

Vilka egenskaper har PS?

The popularity of polystyrene is based on a number of technical properties that make it easy to work with and predictable in industrial processes:

  • High rigidity: the material maintains its shape well under load, which is critical for structural components.
  • Excellent dimensional stability: PS has low shrinkage during injection moulding, enabling the manufacture of high-precision parts.
  • Good dielectric properties: it is an excellent electrical insulator, making it suitable for electronic components.
  • Low moisture absorption: Similar to POM, polystyrene absorbs very little moisture, meaning its properties do not change in humid environments.
  • High gloss and transparency: in its basic form (GPPS), the material offers glass-like transparency.

Common uses for PS

Thanks to the material’s versatility and workability, polystyrene is used in a wide range of technical applications:

  • Laboratory equipment: due to its transparency and chemical resistance to water-based solutions, it is used for Petri dishes and test tubes.
  • Covers and casings: in the electronics industry, HIPS is often used to produce rigid, protective casings for domestic appliances and office equipment.
  • Insulation material: in its expanded form (EPS), this material is the standard choice for thermal insulation in the construction sector.
  • Food packaging: the material’s rigidity and approval for food contact make it a common choice for everything from packaging components to disposable items.

Benefits of PS

The main advantage of polystyrene is its balance between performance and cost. It is a cost-effective material that is very easy to process using both injection moulding and thermoforming (vacuum forming).

Its rigidity makes it possible to produce thin-walled yet sturdy components, which can reduce material consumption. Furthermore, polystyrene is completely odourless and tasteless, which is a key advantage in medical technology and food handling.

Disadvantages and Limitations

To ensure the correct choice of material, it is important to be aware of the limitations of polystyrene. The material has a relatively low temperature resistance and begins to soften at temperatures as low as 70–90°C.

Standard polystyrene (GPPS) is also very brittle and can crack when subjected to mechanical stress. It also has limited resistance to organic solvents and oils, and is sensitive to UV radiation, which means that, without additives, it is not suitable for long-term outdoor use.

The difference between PS and other plastics

When compared to ABS, polystyrene (particularly HIPS) offers a similar processing profile but at a lower cost, although ABS has higher impact resistance and better heat resistance.

Compared with polypropylene (PP), polystyrene is considerably stiffer and more dimensionally stable, but PP offers better chemical resistance and can withstand higher temperatures. PS is often the material of choice when requirements for stiffness and transparency take precedence over the need for toughness.

When is PS the right choice of material?

Polystyrene is the right choice when you're looking for a rigid, dimensionally stable, and cost-effective material for indoor applications. It is particularly suitable for parts with complex geometries that require a high surface finish or transparency.

The choice of plastic should always be based on the specific application and its unique requirements. To ensure optimal performance in your design, we recommend consulting a materials expert early in the project phase.

Would You Like to Know More?

If you have any further questions or concerns about polystyrene (PS), please feel free to contact us. We'd be delighted to tell you more!

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Frequently asked questions about PS

  • Polystyrene is a thermoplastic that becomes malleable when heated and can be reshaped several times without altering the material’s basic structure.

  • The material is easy to shape and machine, making it suitable for the mass production of components with relatively simple geometries.

  • Polystyrene is rigid but relatively brittle, which means it is better suited to static applications than to parts that are subject to impact or vibration.

  • Yes, polystyrene has good dimensional stability, which means that components retain their dimensions under normal use and at a stable temperature.

  • Polystyrene has limited chemical resistance and can be affected by certain solvents, which should be taken into account when selecting materials.

  • Yes, polystyrene can produce a smooth, even surface, making it suitable for applications where surface finish is important.

  • Unlike tougher engineering plastics, polystyrene is stiffer and more dimensionally stable at the impact and fracture limits.

  • Polystyrene is best suited to environments with relatively stable, low temperatures, as high heat can affect the material’s shape and performance.

  • It may be a good choice for applications where the load is low and the environment is controlled, but less suitable in more demanding environments.

  • The choice should be based on requirements regarding rigidity, precision, temperature, chemical exposure and whether the component is subject to mechanical stress.