With phenolic insulation boards entering into the market from all over the world knowing about their differences has become vital. Because what might look the same on the outside may not always be the same on the inside.
When comparing different phenolic solid foam insulation panels, it is important to distinguish between ‘open cell’ and ‘closed cell’ designs, as their respective performance characteristics vary widely.
Open cell foam
In an open cell foam the blowing agent forms irregular pockets that are linked together into a continuous interconnected capillary network.
Because the pockets, or cells, are open, the blowing agent will quickly disperse into the atmosphere and the cells will refill with the surrounding air. Immediate transfer of air or water vapour is enabled through the ‘open’ or ‘porous’ interconnected material structure, just like a sponge. The effect of replacing the very low conduction gas with air is to diminish the thermal resistance of the material significantly.
An example of an open cell foam is the bath sponge where water can easily flow through the entire structure, displacing the air.
