Density

The density (more precisely, the volumetric mass density; also known as specific mass), of a substance is its mass per unit volume

The same Polyurethane item  can be produced in a variety of densities with different final result.

The two reactant liquids (polyol and isocyanate) combine to form a solid polymer (polyurethane), which may be elastic or rigid. This solid, however, may also contain bubbles making it a cellular foam material (low density). These bubbles can either be formed chemically or physically. Chemical blowing can be achieved by adding water to the polyol, which in turn reacts with the isocyanates to form carbon dioxide gas bubbles. Alternatively, physical blowing is achieved by adding in a substance with a relatively low boiling point, such as pentane. As the exothermic polymerisation reaction proceeds, the pentane heats up and evaporates into bubbles.

This procedure can be controlled depending on the application at hand. For example, a shoe sole may be ‘blown’ to twice its volume, whereas cushions may be blown to 30-40 times the volume. In some low-density foams for cushioning and insulation, only 3% of the total volume is made up of solid polyurethane

With us, You can chose densities between 90Kg/m3 and 1200Kg/m3. The final proprieties will be as well different.