Silicone Rubber (siblings)
Silicone vs EPDM Rubber
Silicone rubber and EPDM are both widely used in weatherstripping, automotive seals, and outdoor applications. Silicone offers superior temperature range and biocompatibility; EPDM offers lower cost and better resistance to steam and hot water.
Applications
- Automotive door and window seals (material selection)
- HVAC ductwork sealing
- Outdoor weatherstripping
- Industrial process equipment seals
Key Features
- Silicone: −60 °C to +230 °C vs EPDM: −50 °C to +150 °C
- EPDM: better steam resistance and lower cost for general outdoor use
- Silicone: better for high-temp, food-contact, and medical applications
- EPDM not food-contact approved; silicone FDA/LFGB compliant grades available
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Technical Details
Silicone vs EPDM Rubber: Material Comparison
Silicone rubber and EPDM (Ethylene Propylene Diene Monomer) rubber are both widely used in sealing, weatherstripping, automotive, and industrial applications where weather resistance, ozone resistance, and service longevity are required. This comparison helps designers and procurement engineers select the correct material for their application based on temperature, chemical, and regulatory requirements.
Where They Overlap
Both silicone and EPDM offer:
- Resistance to atmospheric ozone (both are rated for outdoor weatherstripping)
- UV resistance (both resist UV-induced cracking in outdoor exposure)
- Non-black colors (both available in black; silicone in a wider color palette)
- Shore hardness range Shore 30A–80A (with different property profiles)
- Processing by extrusion, compression molding, and calendering
In these overlapping areas, EPDM is almost always chosen over silicone for cost: EPDM is typically 3–5× cheaper per kilogram than comparable silicone rubber compounds.
Temperature: The Key Differentiator
| Temperature Criterion | Silicone | EPDM |
|---|---|---|
| Continuous service maximum | +230 °C | +150 °C |
| Short-term maximum | +300 °C | +175 °C |
| Low-temperature limit | −60 °C | −50 °C |
| Compression set at 200 °C | <25% | Fails (softens) |
EPDM begins to lose compression set resistance and soften above 150 °C. For seals continuously exposed to temperatures above 150 °C — valve cover gaskets, turbocharger system seals, exhaust-adjacent components — EPDM is not a viable option. Silicone operates continuously to 200–230 °C.
Chemical Resistance Comparison
Hot water and steam: EPDM is superior. EPDM maintains properties in steam autoclave conditions (121–134 °C, 100% humidity) significantly better than silicone, which can soften slightly and lose strength at high-humidity high-temperature conditions. For steam sealing applications, EPDM is preferred.
Oils and fuels: Both silicone and EPDM have moderate-to-poor resistance to petroleum oils, fuels, and hydraulic fluids. Neither is suitable for continuous immersion in concentrated petroleum products; nitrile (NBR) rubber is the correct choice for oil-seal applications.
Ozone and UV: Both resistant. In most outdoor applications, EPDM and silicone perform equivalently over 10–20 year service lives.
Acids and alkalis (dilute): Both resistant. For strong acids or alkalis, select based on concentration and temperature.
Food Contact and Medical Applications
Silicone: FDA 21 CFR, LFGB §30/§31, and USP Class VI grades widely available. Silicone is inherently food-contact safe when formulated as platinum-cured grade.
EPDM: Food-contact EPDM grades exist (FDA 21 CFR 177.2600 compliant EPDM is available) but LFGB and USP Class VI EPDM is much less common. For baby products, medical devices, and baking equipment, silicone is the practical choice.
Cost Decision Matrix
| Application | Choose | Reason |
|---|---|---|
| Automotive door seals (standard) | EPDM | <150 °C, cost-sensitive |
| Valve cover gasket | Silicone | >150 °C continuous |
| Outdoor window weatherstripping | EPDM | <150 °C, 3–5× cost advantage |
| Baking mold | Silicone | FDA/LFGB required, 230 °C oven |
| Baby products | Silicone | Biocompatibility + food-contact |
| Steam pipe insulation | EPDM | Better steam resistance |
| Turbocharger hose | Silicone | 200 °C+ hot side exposure |
Contact us to discuss material selection for your specific application and request samples of silicone or EPDM from our supplier network.
Article Type
Material Comparison
Key Factor
Temperature, cost, food-contact
Availability
In Stock