Peroxide Silicone Sponge or Platinum Cure Silicone Sponge?

In HCR silicone, Platinum-cured silicone sponge is becoming more popular. People are asking more and more for an FDA compliant sponge. In fact they are more than likely asking for a non Azo blowing agent and platinum cure. If you select a platinum silicone sponge you have to be aware first of the limitations and well as the positives.

The first and most obvious limitation is the density. You will be lucky to achieve a density of 350kg/m3 where as the standard sponge can achieve 100kg/m3. The second is the price which is also linked to the density. The compound cost is likely to be around twice the usual cost and you need more compound due to density limitations. The next issue when selecting platinum is the temperature limitations, people usually select silicone due to the high-temperature rating. But when platinum cured you are lowering the temperature by up to 80C when compared to a peroxide cured with heat age additives. Another negative in this world of high energy costs is the high temperature needed for platinum sponge. The temperature needs are near % higher.

The positives are platinum has relatively no odor. The compression set for ASTM 1056 is also excellent if you are able to keep the sponge closed cell. There are a number of options for platinum sponge for various silicone manufacturers. Many that I have seen make an open-cell sponge and certainly partially open-cell. A lot depends on the experience of using the material and the temperature that it is processed.

So where does this leave you? Well, I think in the next few years platinum sponges will get better in regards to density. There is also the complication of recent history in regards to non-chlorinated peroxides becoming the norm within Europe and beginning to raise its head in the UK Elastomer Innovations on the other hand is researching and developing a hybrid of the 2. A non-Azo blowing agent with non-chlorinated peroxide. There is some work to go, but initial sponges have shown promise and have the benefits of the 2 types of sponges.

If you need advise on both Azo sponges for extrusion and sheeting and platinum sponges for both process please get in touch with us at Elastomer Innovations.