Silicone rubber materials and some plastic films have chemically inert and non-porous surfaces, which equates to low surface energy. This means they have a weak molecular bonding force making it difficult to create a bond with many pressure sensitive adhesives.

Per the Rogers Corporation Website, Rogers “BISCO HT-800 Medium Cellular Silicone offers the lightness of foam with the enhanced sealing capabilities of sponge rubber.” In this post, we are going to dive a little deeper into this excellent material.

Silicone Rubber, a "Low Surface Energy" Elastomer, what does this mean?

Silicone is a high performance elastomer with the ability to withstand extreme temperatures, both high and low. It also naturally repels, which makes it an excellent choice for a water seal or a moisture barrier. However, this also makes silicone tricky to bond to other surfaces.

Technological advances in properties of soft, flexible foam and elastomeric materials have continued to advance. These thick, soft, flexible foams and elastomers are ideal materials for sealing, gasketing and cushioning across many industries and applications. They compress, form to irregular surfaces, bend, and flex within an application without damage or de-lamination, but from the perspective of the die cutter, may also introduce challenges when trying to achieve the tight dimensional tolerances common in metal and plastic-molded parts.

BISCO® HT-800 Silicone Screen Gasket for Navigation / Infotainment Module

We have published a new customer success story!  In this story, the customer required a static seal for a navigation module that would be contained and used on the exterior of a recreational vehicle. The exterior navigation/infotainment module would be exposed to outdoor elements including extreme temperature swings, rain, wind, and dust. The gasket was required to reliably perform for the life expectancy of the class A RV. This could be more than 10 years! The customer came to Marian for a solution.  

Video Demo: Thermal Resistivity and Conductivity of Silicone Foam

Thermal resistivity and thermal conductivity can be two very important physical features of foam materials for certain applications. Most devices containing electronic components must be designed to deal with heat in one way or another. Electronic circuitry operates most reliably at lower temperatures.  High operating temperatures decrease the service life of the device or module. It is critical for designs to either conduct or isolate heat away from delicate components to ensure ideal operating temperatures.

When choosing a foam for a product design, one feature that should be considered is the compression set resistance of the foam.  C-Set is one of the most important characteristics to consider, and this blog post answers three basic questions to explain why. 

Imagine going 65 mph in your vehicle while on a road trip. The road you are driving on is old, so your vehicle bobs up and down the many dips and divots; your speakers are loud and are causing your rearview mirror to vibrate, making it hard to see; and your moon roof has a roaring noise sneaking through the cracks. These foul disturbances are examples of NVH, also known as Noise Vibration Harshness.

Marian has a brand new demonstration piece to share with the world! Strategically named "Test My Memory," the demo illustrates the impact of compression cycling over time with 4 different foams. Neoprene, Polyethelyne, PORON Urethane, and BISCO Silicone are tested by being compressed for 48 hours.

Foam Material Compression

In the demonstration, you will see that certain foams depreciate as they take on impact over time, whereas other foams resist the compression set by returning to their original thickness. The material characteristic of being able to take a compression set, also called compression force defection, is extremely important in long-term sealing applications. The ability of the material to "push back" to fill in any potential gaps that would allow water or dust to pass through is critical. This makes such materials an excellent option for sealing gaskets. We wrote an entire blog post about compression force defection, you can read it here: Compression Force Deflection in Foam Gaskets: A Critical Property

Compression Force Deflection

Applications that experience periodic compression cycling over time may require a gasket that is capable of compression rebound. In the event that your application uses a material that does not resist compression force, the material may depreciate over time. When your gasket has dwindled or has deteriorated from all of the periodic compression cycling, your gasket will become ineffective and will need to be replaced. In a perfect world, your gasket should rebound to fill any potential gaps. Using a material with great compression resistance will guarantee a long-term sealing performance that will work just as effectively each time you reseal your application.