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Closed Cell Foams & Sealing

Closed cell foams are a great alternative to open cell foams for certain applications. Closed cell foams come in a variety of blends, densities, and colors. Open cell foams allow water to pass through as well as absorb water. Closed cell foams do not allow water to pass through and also limit the absorption of water. We are constantly looking for new types of closed cell foams to fit any application. In this newsletter we will cover some of the closed cell foams we have available as well as open celled materials that can be used for sealing applications.
               
Cross-linked polyethylene, or XLPE, is a light weight closed cell foam that is available in a variety of colors. We typically carry XLPE in two pound and four pound densities and in white, grey, or a black, but we are able to order XLPE in other colors or densities if necessary. XLPE is commonly used in thermal insulation applications due to its thermal conductivity value of 0.25 BTU-in/hr-ft²-°F and being able to withstand temperatures above 210°F as well as low temperatures of -65°F. Cross-linked also works well for gaskets, seals, and packaging inserts and is also used as a Class A surface protector.  XPLE’s fine cell structure allow it to be used for applications where there is high water exposure or flotation needs. 

Another polyethylene foam we have available is our Expanded Polyethylene, or EPE. EPE features excellent dimensional stability and recovery, while also providing cushioning protection against repeated impacts. It is also chemical and water resistant. We carry EPE in a variety of colors and densities ranging from 1.2 lbs/ft³ to 9.0 lbs/ft³. EPE’s can also be made with anti-static and flame retardant properties should the application require them. Typical uses of EPE include electronics protection, packaging, gaskets, and flotation devices. 

Lastly, we have our Beaded Expanded Polyethylene, or BPE. BPE has a beaded cell structure which is larger than EPE and XLPE. The benefit of the larger cell structure is that it provides the foam with a greater durability. BPE provides excellent energy absorption properties, weight to strength ratio, and it is resistant to water, oils and most chemicals. It is also available in a range of densities from 1# to 4.2#. Typical applications for beaded expanded polyethylene include: packaging, flotation devices, and seals. Pressure sensitive adhesives are easily added to any of the aforementioned polyethylenes for any attachment needs.
               
EPDM, Neoprene, EPDM/Neoprene/SBR blends, NBR/PVC/CR blends, Nitrile, ECH, and EPT are some of the closed cell foams we have available. Each polymer has its own benefits and can be used for a variety of applications depending on the need. Ethylene propylene diene monomer, or EPDM, is used when the application requires resistance to heat, ozone and weather. EPDM is able to withstand temperatures up to 300°F and features excellent UV and ozone resistance. Neoprene closed cell foam is similar to EPDM in that it has a fine closed cell structure and excellent resistance to low and high temperatures, but it does not have as high of an ozone resistance. EPDM/Neoprene/SBR blends along with NBR/PVC/CR blends, are a combination of different polymers to create new closed cell foams. The blending of polymers allow the closed cell structure to have improved performance. Each blend has varying densities and properties. Closed cell blends offer lasting protection against condensation, water, and heat gain or loss. Their formulation provides outstanding compression set resistance for consistent performance in demanding applications. Nitrile, or NBR, is a synthetic rubber copolymer of acrylonitrile and butadiene. The composition of nitrile allows it to be resistant to oil, fuel, and other chemicals. Epichlorohydrin, or ECH, is a softer closed cell foam that features excellent resistance to UV, ozone, heat, oils, and fuels. ECH is able to withstand temperatures up to 300°F. While it does have a lower compression set compared to other closed cells, it is still an excellent option. Last we have our Polyethylene Butyl, or EPT. EPT is similar to EPDM in that it is able to withstand extreme conditions, but it does not have the tensile strength that other closed cell foams offer. EPT is a softer closed cell foam and is resistant to weather, heat aging, cold, and chemicals as well as having electrical insulation properties, allow it to be used in a variety of applications. Typical applications for all of the closed cell foams mentioned above include: gaskets, seals, padding, stripping, insulation and hoses. 

Lastly, we have our cellular silicone and cellular urethane materials. These are actually open celled structures however under compression, act as good as or better than other closed cell polymers for sealing applications.  These materials are made from a firm grade silicone which gives them the lightness of foam with improved durability and sealing of rubber. The cellular silicone that we carry comes in medium, soft, and extra soft firmness and black and grey colors. Cellular silicone features excellent memory and low stress relaxation which will help reduce the maintenance cost associated with gasket failures due to compression set and softening. They offer superb flame resistance and fire protection as well as being able to withstand temperatures up to 482°F, when used intermittently. Having resistance to environmental extremes, mechanical resilience and safety features make these cellular silicones perfect for applications in transportation equipment, communication and electrical enclosures, electronic products and components, industrial equipment, and appliances. Pressure sensitive adhesives can be added to our cellular silicone materials as needed.

We also carry cellular urethane materials. These materials come in a variety of types such as extra soft, very soft, soft, firm, and very firm. It can also be enhanced with greater closed cell content to provide extra sealability. These cellular urethanes feature excellent compression set resistance which allows them to provide durable, long lasting performance. They also have low-outgassing and are non-fogging, while containing no plasticizers or residual chemicals. These materials will not become brittle and crumble and are non-corrosive to metal. Cellular urethanes are great for gasketing, sealing, cushioning, and vibration isolation. 

In this newsletter we have covered a wide variety of closed cell and sealing materials we have available. Ranging from different blends to cross-linked polyethylenes, single rubbers, and cellular silicones and urethanes. Each have their advantages and disadvantages such as cellular silicones and urethanes are fantastic for sealing, but come at a higher cost. Other factors include the environment the part will be in as well as the size of the part. Because of this, we highly recommend you allow us to suggest the best material for your application.

If you would like to give any of these materials a try for your application, give your account manager a call today! You can also reach us at 262-783-3300 or email us at info@milcut.com.

Copyright © 2016 Milcut Inc., All rights reserved.


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