5. Product control

5.1 Expandable polystyrene

Molecular weights are generally measured by gel permeation chromatography (GPC), and pentane and residual styrene monomer contents by gas chromatography. Granulometry is controlled using sieves.

These physico-chemical measurements are not enough, and it is necessary to transform the product (pre-expansion and molding) to determine its actual behavior.

This is achieved using small-scale equipment. In this way, for example, the bulk density obtained under given expander setting conditions can be determined. Similarly, a cycle time can be checked during the molding phase, followed by a given physical property of the molded product.