Density of Polyurethane: Density is defined as the amount of weight per unit volume and measured in terms of kg/m3. Density is one of the most important properties of the polyurethane and it affects the durability and the power of support. High density products maintain their original properties longer. If more polymer material is used, then the better the foam will be obtained.
Hardness of Polyurethane: Hardness in the flexible polyurethane is defined as the measurement of the surface touch and feeling of the foam. Therewithal, the support is the ability to push back against the weight of the foam. Hardness and support affect the comfort of the foam together. There is no direct relationship between the hardness and the density of the polyurethane. As a common mistake, the high density foam is thought to be harder. In fact, the density is totally independent to the hardness. Hardness of the foam is measured as the amount of force required to compress up to 40% of its height.
Fatigue of Polyurethane: Fatigue test is an indicator of foam durability. In this test, a weight of 70 kg force is applied to the foam sample 80,000 times, and the sample is compressed. The hardness of the sample must be measured before starting this test. The hardness of the sample is measured again after the test is completed. Finally, the hardness is measured again after 6 hours. The difference between this hardness value and the first value, is divided by the first value. So, the loss of stiffness is determined in percentage.
Fatigue (test) is primarily important if the foam uses in a bed. This test provides to evaluate the performance of flexible polyurethane foam during usage. This test is simply equivalent to a person who has 70kg weight uses this bed during 15 years. The test is performed in accordance with TS3460 EN ISO 3385 standard.
Flammability of Polyurethane: Polyurethane materials can emit some toxic gases, heat, fume or some components caused to corrosion while pre-ignition, combustion, burning occurs depending on the properties of polyol and isocyanate they contain. This condition causes not only thermal but also non thermal problems. These problems can be reduced by increasing the fire resistance of polyurethane. For this purpose, various techniques are used. The most common of these is the addition of flame retardants. Flame retardants provide secure usage areas against fires. Besides, they provide tensile and bending strength, resistance to impact breakage, viscosity, resistance to oxygen and UV rays.