Effect of expandable and expanded granules diameter on the properties of hybrid-lightweight panels

The aim of the present study was to produce hybrid low density panels using wood fiber as surface layers and a mixture of wood particles and polystyrene granules as core layer. The effects of the most important factors on panel properties were investigated. Hybrid lightweight panels were produced with a density of 520 kg/m3 using polystyrene granules as filler in the core layer. The type of polystyrene granules (expandable and pre-expanded shapes) and granules diameter (fine, medium and large) are the most important factors which can influence the panel properties were also investigated in this study. The results showed that the granule type had significant effect on the physical and mechanical properties of panels. The modulus of elasticity and face screw withdrawal resistance were increased in case of pre-expanded granules, while the internal bond values improved in the case of expandable granules. Mechanical properties of lightweight hybrid panels were significantly enhanced by increasing the diameter of both granules forms (pre-expanded and expandable). Thickness swelling was lower in the case of fine granules. But the granules diameter had no significant influence on the water absorption values. It can be concluded that the expandable filler with larger diameter can be used as filler for the production of lightweight panels.