Silicone Foams Guide
The unique qualities of silicone foam make it a significant material in numerous sectors, including aerospace, automotive, construction, and electronics.
What is Silicone Foams?
Silicone foam products are produced from platinum-cured, liquid silicone rubber. The raw compound is expanded and distributed on a continuous casting line, then heat cured.
The expansion process is managed to provide a range of products with varied densities, softness/firmness, and cell architectures. Silicone foam materials often have smooth skin on one or both sides due to the casting process.
The final product has lightweight, flexible, and has a homogeneous cell structure that makes it appropriate for a number of applications. comprising thermal and acoustic insulation, sealing and gaskets, cushioning, and vibration dampening.
Open-cell Vs Closed-cell Silicone Foam Structure
Silicone foam is available in both open-cell and closed-cell foam structure
Open cell foam structure permits excellent absorption of water, moisture, and dust – making it perfect in a conventional sponge used for washing automobiles.
- Closed cell foam structure doesn’t accommodate for the absorption of water, moisture, or dust – making it excellent in sealing applications where water and dust need to be kept out. This kind is intrinsically hydrophobic (repels water) (repels water).
Benefits of Silicone Foam
- Wide working temperature – silicone foam has a temperature range of -67°F to 392°F (-55°C to 200°C).
- Easily fabricated into various types of foam gaskets, pads, tapes and sealing profiles
- Available in various densities and shapes
- Excellent performance on sealing, cushioning, soundproofing
- UV and ozone resistance - silicone goods have exceptional UV and ozone resistance due in part to their inorganic backbone. This gives a long-lasting performance.
- UL gasket - most silicone foam materials sold by LGDsilicone Elastomerics are UL 94 flame certified and UL 50 and UL 50E rated for the gasket.
Properties of Silicone Foam
A. Physical Properties
- Closed Cell Foam Material
- Good performance at severe temperatures
- Excellent fire resistance
- Low compression set
- UV and ozone resistance
B. Chemical Properties
| Mechanical Properties | Metric | English |
|---|---|---|
| Hardness, Shore A | 3.0 - 62 | 3.0 - 62 |
| Hardness, Shore OO | 40 - 70 | 40 - 70 |
| Tensile Strength, Ultimate | 0.0552 - 2.80 MPa | 8.00 - 406 psi |
| Tensile Strength, Yield | 0.172 - 1.24 MPa | 25.0 - 180 psi |
| Elongation at Break | 49 - 300 % | 49 - 300 % |
| Compressive Yield Strength | 0.00800 - 0.170 MPa | 1.16 - 24.7 psi |
| Compression Set | 0.00 - 80 % | 0.00 - 80 % |
Applications of Silicone Foam
- Automotive Foam Gaskets, Pads, Tapes
- Industrial Foam Parts
- Medical Devices
- Flooring Underlay
- Manufacturing Equipment
- Sealing and Cushioning Applications
- Indoor lighting (dust gasket, UL 94V-0)
- Instrumentation (vibration dampening)
Silicone Sponge Vs. Silicone Foam
While both silicone sponge and silicone foam have superior sealing qualities at increased temperatures, there are small variances in the materials. Silicone sponge is compounded and combined on a 2-roll mill and then cured in an oven. Silicone foam is manufactured from a liquid silicone which is extruded and cured in an over. Both are cellular.
| Characteristic | Sponge | Foam |
| Raw Material | Gum-based silicone, mixed and cured in an oven | Liquid silicone extruded and cured in an oven |
| Min Max Use Temp | -73oC +260oC -100oF + 500oF | -51oC +200oC -67oF + 392oF |
| Flammability | UL 94 HBF (horizontal burn formula is available V22-300) | UL 94 V-0 Vertical burn - better flame rating than sponge |
| Compression Set | Good (a lower compression set formula is available V22-210) | Better compression set than a sponge |
| Tensile Strength | High tensile strength; higher material weight | Lower tensile strength than a sponge; lower material weight. Easier to tear by hand. |
| Density | Soft Silicone Sponge = 21-30 PCF (pound/cubic ft) typical Medium Silicone Sponge = 29-33 PCF typical Firm Silicone Sponge = 40 PCF typical | Soft Silicone Foam = 12 PCF typical(pound/cubic ft) Medium Silicone Foam = 22 PCF typical |
| Compression Deflection | Soft Silicone Sponge = 5-9 PSI typical Medium Silicone Sponge = 6-14 PSI typical Firm Silicone Sponge = 12-20 PSI typical | Soft Silicone Foam = 3 PSI typical Medium Silicone Foam = 9 PSI typical |
| Note: The information provided is for reference and the user must determine if a particular | ||
Silicone sponge tends to be greater in density, have stronger rip strength, and has a higher usage temp (up to 500F compared to 392F for silicone foam) (up to 500F compare to 392F for silicone foam) Essentially silicone sponge has greater physical and mechanical qualities than silicone foam.
Silicone foam tends to be softer, lower in density, and has lower compression set properties. Since it includes more air, it provides superior thermal insulation. Silicone foam also provides greater flame retardant qualities which are important in aeronautical applications. Neither substance absorbs much water, therefore silicone "sponge" is frequently a confused descriptor.