📌 1. Raw Material Quality
Polystyrene raw material (PS): Must be of high purity and low residue content.
Pentane content: The blowing agent that enables expansion is usually pentane. It must have low volatility and be at an appropriate level (between 4–7%).
Particle size: Uniform size distribution ensures a homogeneous structure during expansion.
📌 2. Pre-Expansion
Correct expansion ratio: A density of 12–40 kg/m³ is generally targeted.
Steam quality: Clean and dry steam should be used. Low-pressure (0.3–0.6 bar) steam is ideal.
Homogeneous expansion: Particles of the same density should be obtained so that no problems arise during moulding.
📌 3. Intermediate Resting (Stabilisation)
Minimum 6–24 hours: The expanded particles must be left to rest to achieve pressure and temperature equilibrium.
Good ventilation: This is important for the removal of pentane vapour and particle hardening.
Moisture control: Excess moisture can lead to mould growth and poor bonding.
📌 4. Moulding / Shaping
Appropriate vapour distribution: Homogeneous vapour pressure in the mould ensures that all particles bond evenly.
Mould temperature and time: Insufficient time → weak bonding, excessive time → causes deformation.
Cooling: Must be controlled and rapid. Slow cooling can cause product deformation and high shrinkage.
📌 5. Product Quality and Tests
Density measurement (kg/m³)
Compressive strength (kPa): Particularly important in the packaging and construction industries.
Thermal conductivity (λ): Should be low if used as insulation material (approximately 0.030–0.040 W/m·K).
Fire resistance: If flame retardant additives are used (e.g., environmentally friendly alternatives to HBCD), an effective mixture must be ensured.
Dimensional stability: There should be no long-term shrinkage or deformation.
📌 6. Environmental and Safety Criteria
Emission control: Pentane and other VOC emissions should be controlled using appropriate systems.
Recycling: Fire rates should be reduced, and production waste should be made reusable.
Worker safety: Necessary safety measures must be taken during the use of vapour, heat and chemicals.
📌 7. Equipment and Process Automation
Modern, automatically controlled pre-expanders, ageing silos and moulding machines ensure more consistent and higher quality production.
Finding all these criteria in a single provider is crucial for you. That is why EPRO Technologies, with its know-how in both turnkey projects and individual capacity increases, takes you to the point of quality.