Basic knowledge of expandable polystyrene (EPS)


In 1950, BASF developed EPS. Because of its excellent thermal insulation performance, it was widely used in the construction field. Later, it was widely used in packaging because of its strong impact resistance.


When EPS raw material beads are smashed into production, foaming agent has been mixed in, generally 4-7% pentane. In the mold, high-temperature steam is used for foaming and molding, and up to 98% of the finished product can be air. Beads can be divided into flame-retardant and non-flame-retardant, and can also be divided into large, medium and small according to their radius.


Production process: pre-foaming → curing → molding

Pre-expansion: Use 80-100℃ steam to heat the raw materials to increase the beads by 40-50 times.


Maturation: The pre-expanded beads are dried in the silo to equalize the internal pressure. The beads will have greater mechanical elasticity.


Molding: The pre-expanded and dried beads are transferred to the mold, and steam is added again to make the beads stick together to form a finished product.


Features: low thermal conductivity, low density, high mechanical properties, low water absorption, easy operation and installation, aging resistance, sound insulation, and buoyancy.


The closed-cell structure allows it to cushion impact by changing and restoring deformation. The thermal conductivity is 0.033-0.043W/(m·k). Prolonged exposure to ultraviolet light will affect performance. It has no nutritional value, will not be eroded by mold, and will not decompose any water-soluble substances that pollute groundwater.


A study by the School of Packaging at Michigan State University found that when EPS is used to package fruits and vegetables, the carbon dioxide released by them will be retained, delaying maturity, and maintaining the content of vitamin C more effectively.


Industry Challenge:


  1. Fire.The flame retardancy of EPS is usually improved by adding flame retardant.


  1. Recycling. Physical recovery method: The recovered and compacted volume becomes one 40th of the original, which is convenient for transportation and used for re-production. The dissolution method is costly. Used for incineration for energy recovery. EPS is not easily degraded and can be used for landfill.


Prev: Equipment needed for producing EPS foam box

Next: The primary application scale of EPS foam machinery and equipment – EPS …