In this in-depth article, we’ll take you through the features of polyurethane foam mattresses, the differences to memory foam and coils, and consumer reviews.
Characteristics of polyurethane foams
From a structural point of view, polyurethane foam has a cellular texture that encloses a very high percentage of air between its plies, this characteristic has made it one of the most widely used materials in thermal insulation, electrical engineering and for the construction of safes. and above all light.
Of course, when we talk about polyurethane, we are referring to a large family of polymers that have bonds called urethane (for those unfamiliar with chemistry, they are nitrogen-based organic compounds), but the one used in the mattresses is a type of polyurethane with open cells which therefore allows good breathability, thus avoiding the proliferation of mites and mold.
The polyurethane foam used for mattresses has quite interesting physical properties to ensure a superior quality rest compared to spring mattresses, let’s find out which ones:
For example, the density – that is, the weight per unit volume – of this type of mattress is extremely low, precisely in relation to the fact that the open cell accommodates a lot of air. It follows that with equal dimensions, a foam mattress will be much lighter than a traditional mattress, this will give it greater maneuverability which will be appreciated in the morning when it is time to make the bed. To learn more about this issue, we recommend reading ours memory mattress density guide.
Resilience defines the elasticity of the mattress. To obtain this value, a standard size steel ball is used which is dropped onto the polyurethane foam sample.
Of course, a standard value is also defined for the height from which the sphere is released. Once the sphere is hit, the sample will bounce and the height it will reach after the bounce will be measured and used as a parameter to measure the resilience.
The higher its value, i.e. the more the steel ball bounces, the better the quality of the foam.
Also the lift – the measure of resistance to a load – is an element of pride for foam mattresses, in fact compared to a traditional type mattress the ability to resist deformations due to the weight of foam mattresses is much higher. .
This way, you can lie on your bed without it giving way excessively to your weight and forcing you to adopt unnatural postures. Lift is tested by compressing a 323 square centimeter plate to the thickness the manufacturer intends to use.
For example, if we fix ourselves to have a flattening of 25% on the sample, we will see what force it will be necessary to use to obtain this deformation, the value of the force that we had to apply, expressed in Newton, will be to express the capacity load-bearing of the mattress. The higher this value, the harder the foam foam it was built with.
I recommend you to read my guide for the hardness of the mattress to sleep well.
Lift should not be confused with compressive strength which is the resistance to a load.
To test the compression of foam mattresses, a force is applied to the sample until a deformation equal to 40% of its original thickness is obtained, also in this case the greater the force necessary to cause this deformation, the more foam foam will be hard to be. Compression, however, is not expressed in Newton but in Kilo Pascal.
Loss of lift due to dynamic fatigue
Another very important characteristic for any type of mattress is the loss of lift due to dynamic fatigue. We all have experience of this phenomenon, surely we have bought a new mattress and found it extremely hard but then, over time, found it getting softer and softer until the shape of our body is permanently imprinted on it.
To measure the ability of the mattress not to lose its lift during use, samples are used that have been subjected to repeated cycles of compression and decompression. At the end of these cycles, the lift test is performed again.
The smaller the difference between the result of the first test and that of the test carried out after the compression and decompression cycles, the better the quality of the polyurethane foam.
Breaking load and elongation
This is one of the most extreme physical characteristics that foam mattresses must guarantee. In practice, a tensile force is applied to the foam sample which first causes it to stretch and then break.
The breaking load is measured in Pascal, the higher its value, the more resistant the foam will be. To carry out this test, the foam is subjected to two distinct and opposing forces. The sample stretches until it breaks.
At this stage, two values are measured: the percentage of elongation and the force necessary to break the sample. The higher the two values, the better the quality of the material.
The mattresses will not be used in aseptic laboratories but in cozy rooms, which is why they are also tested to define the compression set.
It is nothing other than the deformation undergone by the expanded polyurethane after being compressed for a given time and at a given temperature.
The time and temperature used in the test are those that the mattress will face in normal use. The lower its deformation, the better its quality.
Differences between polyurethane foam and memory foam
These materials are quite similar to each other, as memory foam is made by mixing polyurethane foams with additional substances to make this new material heat sensitive.
Differences between polyurethane foam and springs
In recent years, the differences between polyurethane materials and spring mattresses have been reduced, because if on the one hand the problems that afflicted the first generations of polyurethane mattresses have considerably diminished, on the other hand the performance of the structures with springs increased thanks to principles made with pocket springs and areas of undifferentiated lift.
In recent years, many manufacturers have started to produce hybrid mattresses where both technologies are used simultaneously.
The opinions concerning this type of material are quite contradictory, especially if the users have old-generation foam mattresses, which tended to make people suffering from heat sweat (problem solved with memory foam mattress), burying overweight people and giving off bad smells.
When buying these mattresses, it is always convenient to test them in the store, telling the seller your weight, any pathologies affecting the spine and respiratory system and your preferences.
The new foam mattresses, thanks to new construction technologies that shape the structure and guarantee differentiated bearing capacity, customizable density and above all internal ventilation of the bearing structure, have considerably reduced the old problems reported by consumers.