Sponge rubbers
closed and semi-closed cell:
Nothing escapes

Hello good morning. Closed or semi-closed cell rubbers, well, closed cells are rubbers that, as the word says, the cells do not communicate with each other when vulcanizing.

They remain independent of each other, so what happens? That by being independent they create a much greater or almost complete hermeticism, which is not an open cell. And the semi-closed cell is a product that…

It came out relatively recently, it is a product that was developed for the automobile industry, because it had special characteristics. And, as the word says, they are semi-closed, some communicate and others do not. It makes an isolation different from that of complete closed cells.

Well, actually the manufacturing of these rubbers… That is, we do not manufacture. We have been manufacturing closed cell rubber with natural rubber for years, but they are very complex formulations and only a few chemists know how to develop a formulation so that the product can be manufactured.

Normally, most of us manufacturers are transformers, that is, we buy the product already manufactured. We cut it, laminate it and glue it.

We, as I have said in the past, have manufactured, well, formulas are made with peroxides that what they do is increase the volume of the cell, of the sourdough, let’s say, of the mother mixture.

They increase by three, but hey, the machine has to have a closure so it doesn’t get in, etc. Well, a series of conditions and an appropriate formulation so that… You put in a plank, a 2×2 mix and you get 5×5.

They are called explosive because what they do when vulcanized is multiply their size several times.

They are called explosive because what they do when vulcanized is multiply their size several times.

Common applications of sponge rubbers are both closed cell and cell sponge rubbers.

Well, as I have told you, the semi-closed cell has a little more specific uses. Well, as I have told you, the semi-closed cell has a little more specific uses. These ones that catch, absorb, bang, and so that the material is not damaged, they put a sheet of cells.

The semi-closed cell, which is giving very good results because it is a very soft material, adapts well to the irregularities of the materials it moves and has resistance to breakage. And then the closed cell sponge, normally the majority use it has is to make closures in metal cabinets.

For metal cabinets, you put the measurement more or less that you need, because there are countless measurements, you cut many measurements. What is the semiclosed cell? The semi-closed cell is the one used to close metal cabinets.

It is a suitable cell and what it does is a closure so that what is inside is not contaminated by dust or anything. It is always sold with adhesive, therefore, to stick it to the metal.

Well, the properties they have, well, I have already told you, one of the most important properties is that it insulates. The inside from the outside of what you are doing together, that is, a metal cabinet isolates the outside from the inside.

And then another property it has is that it withstands environmental conditions very well, that is, it has a very high resistance to ozone. The temperatures are acceptable, it is not a material suitable for high temperatures.

And well, that’s basically it. It is also easy to assemble, it is a material that is assembled by hand, that goes with its adhesive, that is, and that gives very good results. The semi-closed cell is a sponge, therefore, that is used much less and that, well, as I said, because the property it basically has is that it is a soft material, it allows some temperature to pass from the outside to the inside, thus It does not make a total closure, which helps ensure air transfer at a given time.

And it is very soft, it adapts very well to surfaces and then it has important characteristics in terms of sound dampening, all these types of characteristics that are why it is used in the car, which I do not control much because, well, it is not our sector.

Well, actually the density does not affect too much the result of the work that the piece has to do, because these materials are manufactured in various densities, so what the client does is ask you for the density that suits him best. . How affects? Well, man, if you… If you need a material weighing 160 kilos, then if you order it weighing 90 kilos, it will not work for you.

In other words, what you have to know is what density or what hardness is going to work for you and if you don’t make the right choice, well, what is going to happen? Because it’s not going to do the closing well, it’s not going to do the closing that it should do, it’s not going to do it well. That is, it will not be airtight.

Well, no tests are done on these materials, because they are already tested. Since we are not manufacturers, what we do request from the manufacturer is a certificate, it shows that it meets certain parameters of hardness, density and other tests that are carried out, they have a plus minus and that the values ​​are between those parameters and then, well, with Those parameters are what we sell to customers.

Pues… What allows these rubbers to last more or less is that you have chosen a rubber that perfectly adapts to the needs of the use where it is going to be used. In other words, you get the density right, you get the temperature it has to withstand right, you get the tensile strength right.

That is, if you… decide to use a spongy rubber and you are clear about the properties it has, it will probably last a long time because they are materials that do not degrade easily.

If you use it, for example, if the material has to withstand a temperature and you choose it to withstand that temperature, it will last. If you choose… a material that does not withstand that temperature, it will not last. In other words, it is a bit important that you know what the buyer is buying and you as the seller, so that you give him the exact product that he is asking for so that you can get it right.

And if you guess the durability of these materials, it is very high. You mentioned that they have to ask you for it for a specific temperature. For concrete density, for… And I don’t know if they also have to tell you if it’s going to be outdoors or not, and that also affects it.

That, as in all rubbers, since sponge rubbers are manufactured in different types of rubber, depending on the use. That is, for example, there are closed-cell spongy rubbers in nitrile, in natural rubber, in neoprene, in SBR.

It is manufactured in a high variety of rubbers so that, for example, nitrile holds fuel well. Well, that has to be made of nitrile closed or semi-closed cell rubber, because if it is not made of nitrile, it will not resist hydrocarbons.

Then it’s going to come undone. If the rubber you make has to withstand high temperatures, then you have to use neoprene, which will be suitable for high temperatures. If the rubber you are going to use has to have a lot of resistance to tearing, then you cannot use EPDM, you have to use natural rubber in closed cells. In other words, in each situation there is a rubber that is better or worse. So, well, depending on what the client explains to you, where he is going to go, how he is going to go, well, you have to guide him to what type of rubber and what density he is most interested in for what he is explaining to you.

For example, if a guy asks you to make a vacuum system for some cranes that handle wooden planks, you have to give him a rubber that is soft, that adapts well to the differences. That has surface differences and that has resistance to attraction.

I mean, well, for example, in this case the semi-closed cells, well, they work very well.

Let’s see, these materials to hold up… To keep it well, it is best that they are in a closed place, where no light shines on them, and that they are, well, in a closed box with no light.

If you keep it at room temperature, if you keep it at that, at those conditions, then they can last well stored for a long time.

But especially adhesives, over time, even if they are stored very well, they lose properties. Not the rubber, but the adhesive.

The adhesive does tend to leak. And what are they, because this is a sector that, although it seems very stable, also has a lot of evolution, there are beginning to be many changes.

Well, the trend, that is, the trends that we are seeing in the rubber market is that other materials are entering. As they are, although they are not very fashionable now, they are derived from polyurethanes. From plastic.

All these types of materials are replacing, in some cases, rubber, because they are more resistant, they better withstand certain properties that rubber cannot withstand.

But it is true that it is difficult to find substitute materials for rubber because the properties they provide are very specific to that type of raw materials.