Hi TMU,
I have noticed that a lot of online mattress retailers do not mention “memory foam” in their sites. I know that these foams are all polyurethane based but is there a difference in the quality of the foams (especially the longevity and support they provide) when you compare it to a memory foam? Or is it purely a difference in the feel?
Hi MeDave,
Welcome to the Mattress Forum! 
If a manufacturer or retailer isn’t mentioning memory foam specifically, it is most likely that their products do not contain memory foam.
In its most basic description, polyurethane foam is an isocyanate and a polyol and water mixed together to from the foam. Technically, memory foam would be a subset of polyfoam, but one with a viscous nature and with different comfort and recovery properties.
Memory foam is created by reacting an isocyanate and with polyol in presence of a catalyst, water and other additives, and through the manipulation of catalysts and surfactants, partially open cells can be produced, which help create the slow-recovery part of the memory foam process (air is slower in moving in and out of the foam). Another way to create a memory foam (more common) is to manipulate the catalysts and polyols to control the viscoelastic polymer structure, which changes the hydrogen bonding and the glass transition effects in the polyurethane soft phase. So the viscous nature of visco-elastic foam is hence altered.
I was reading an article from a chemical R&D director which stated succinctly that the memory foam is designed on purpose to be a poorly performing spring (polyfoam is a polymeric spring). The specific ratios and additives that foam manufacturers use would be closely guarded trade secrets and you would not find this information shared online. They can vary the firmness, the recovery time, the sensitivity to temperature (viscous nature) and so on. Density and hardness aren’t necessarily related in memory foam, and all memory foam is generally quite plush (ILDs in the 8-18 range are quite common).
There are many factors involved in the overall durability of a material, many of which are discussed in greater detail here. The strongest correlation between durability in memory foam and polyfoam would be the density of the material, and ranges to consider for both polyfoam and memory foam are discussed in this article.
I hope that information helps to clarify some of the differences between polyfoam and memory foam for you.
Phoenix
Hi Phoenix,
I’m sorry for reviving a bit of an older thread… the search has continued for me. I am a pickier sleeper as I have lower back pains and want to buy a mattress that provides really good support. I have noticed that the trend is for most mattress retailers to use polyfoam comfort layers over memory foam. They often tout that this is because it is springy-er. However, I kind of suspect that polyfoam is just cheaper to manufacture. I have also heard that memory foam usually provides better support and is more durable than polyfoam of the same density. Not sure if there is any truth to that but was wondering if you had any thoughts.
Hi MeDave.
I am sorry to hear about your lower back pains.
The trend in the industry for the past 15 years has been designing mattresses that are using comfort foams (memory foam variants and/or newer “age” polyfoams) over a 6" - 7" High Density polyurethane foam support layer. Polyfoam prices vary widely depending on the polyfoam grade. The Polyfoam grade is measured by its density and by its “support factor” or progressive resistance to compression. There are 3 grades of poly foams from the lowest to the highest: Regular conventional (lowest grade), High Density (HD), and High Resilience (HR).
The HD polyurethane foam is commonly used as the very top comfort layer over other higher quality foams used in comfort layers because it is more resilient than Memory Foam and it can be made to be very soft and it is inexpensive to manufacture having a lower cost/inch than other comfort foams. Manufacturers that use lower grades of poly in thicknesses higher than 1.5" in a mattress are usually looking to higher profits … at the expense of long-term suitability, durability and customer satisfaction.
It appears that some of your conclusions are the reverse of the basis for the design. Memory foam does not provide better support than other foams, in fact, it is not found in the support layer of a mattress as it lacks supportive qualities; it is formulated and engineered for comfort more than support. The highest performing mattress support systems are either Latex foam, pocketed coils, pocketed coil/latex combinations or responsive polyurethane with densities 2.0 lb. or higher. Many mattress manufacturers have gone to a hybrid pocketed coil/comfort foam design to achieve balanced support and comfort needs sought by consumers.
I would strongly recommend that you start your research with the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that can help you make the best possible choice … and perhaps, more importantly, know how and why to avoid the worst ones. Two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort”, firmness, and PPP (Posture and alignment, Pressure relief, and your own Personal preferences) that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists based on all the parts of your personal value equation that are most important to you (including the price of course and the options you have available after a purchase if your choice doesn’t turn out as well as you hoped for).
You may wish to peruse some of our Trusted Members here who manufacture high quality mattress products and have the material combinations you seem to be interested in.
Please feel free to come back for any questions you may have once you’ve had the chance to review the information listed above, and perhaps do a forum search to see if any of the mattresses you are interested in are discussed on our forum.
Phoenix