The next episode of Tale of the Tape is here! In part two of this mini series on closed cell polyfoams, Matt covers crosslinked Polyethylene Foams, EVA and EVA blended foams, and PVC foams.
Missed part one? Check out our page to hear about low density polyethylene foam, expanded polystyrene foam, and expanded polyethylene foam.
Transcript:
Hello and welcome to another episode of Tale of the Tape. I'm Matt Tempelis, President of Engineered Materials and your Minister of Tape. Today we're going to talk about the second part of our most common closed cell polyfoam types. Remember, closed cell foams are tiny air pockets packed within the cellular structure of the foam. They create great positive seals because they allow for little to no air and water intrusion. They will see higher levels of compression set and slower recovery after compression than their open cell counterparts. Today we're going to be talking about cross-linked polyethylene foams, EVA or ethyl vinyl acetate foams and their blends, as well as polyvinyl chloride foams or PVC foams. Cross-linked polyethylene foams, best known by the brand name Volara, are soft, flexible foams with fine cell structures. Their typical density ranges from 1.8 pounds to 20 pounds per cubic foot, though more commonly in industry you will see 2 pounds and 4 pound products. Their compression sets are quite good depending on the density ranges from 10% to 25% compression set at 50% compression. You will find them great insulators with Imperial K values around 0.27. They come in extruded form. As you can see here, this cross-linked polyethylene 2 pound product. You can see that skin, that's an extruded form of the product. It also comes in Bun form that can be skived to the thickness of your choice. They're soft, flexible and a very fine cell structure. They are great gaskets, great insulators, great cushioning agents and great separators in industry. Common uses: You'll see them often as double coated foam tapes. Think command strips. Denser versions: Those lily pads out on the lake are cross-linked polyethylene. Again, great gaskets as well. They can be used for indirect food contact and there are FR versions available.
EVA and EVA blended foams come in typical densities from 2 to 5 pounds per cubic foot. They're soft, flexible, resilient foam. For a closed cell foam, they are very resilient and have a low compression set. Compression set values at 50% compression of 10 to 20%. As you can see here by this 2 pound EVA blended product, it's a soft, conformable and fine cell structure product. It is great for lightweight, flexible applications. It's very durable at low temperatures and great UV and chemical resistance as well. For medical diagnostic devices, this is a great product because it has terrific biocompatibility. You'll see applications like gym mats, boat fenders, footwear, as well as industrial gaskets. PVC foams, commonly known by brand names of Norseal or Gaska, have density ranges from 6 pounds per cubic foot up to 25 pounds. They're excellent sealers with a very low compression deflection. You'll see values less than 1 pound per square inch of compression deflection up to about 7. Great thermal conductivity as well. Imperial K values of 0.27 up to 0.3. You can see that compression deflection is quite low on this Gaska product LC 710 PVC foam. You can see that I'm indenting it with very little pressure and it rebounds slowly over time. This is a 15 pound product from Gaska. The V1510. It is harder to compress, probably around 7 pounds per square inch of compression deflection, but you can also see that rebounds a little bit quicker as well. These are great sealing, cushioning, shock absorbing, and insulators. They're used a lot as weather stripping, sealing gaskets, and in HVAC insulators. We've touched on a few more types of closed cell polyfoams and their uses. Remember, at Engineered Materials, we have these materials on the floor to make parts for your application. We'll see you next time on Tale of the Tape.
