Solid EPDM Rubber vs. Santoprene (TPV): Which Material Is Right for Your Seal or Gasket?
Selecting the right elastomeric material for seals, gaskets, or flexible components can make the difference between a reliable long-term solution and recurring maintenance issues. Two of the most widely used materials in these applications—solid EPDM rubber and Santoprene™ (a thermoplastic vulcanizate or TPV)—offer outstanding durability and flexibility but differ significantly in performance, processing, and adhesive compatibility. Understanding these differences will help you select the right material for your application.
What Is Solid EPDM Rubber?
EPDM (ethylene propylene diene monomer) rubber is a fully vulcanized synthetic elastomer engineered for long-term sealing performance in demanding environments. It is known for its weathering resistance, thermal stability, and consistent elasticity across a wide temperature range.
Key properties of EPDM rubber:
Excellent resistance to UV, ozone, and weathering — ideal for outdoor applications.
Performs reliably from –50°C to +150°C with good compression recovery.
Outstanding resistance to water, steam, and polar fluids (e.g., brake fluids and coolants).
Dielectric strength suitable for electrical insulation applications.
Available in a wide durometer range (30–90 Shore A).
EPDM rubber is commonly fabricated into die-cut gaskets, extruded profiles, vibration pads, and weatherstripping. It performs exceptionally in HVAC seals, automotive door and window seals, and outdoor electrical enclosures.
When to Choose Solid EPDM Rubber
EPDM rubber is the right choice for applications that demand long-term durability and environmental resistance, particularly in static or semi-static conditions.
Choose EPDM when:
The application is outdoors or weather-exposed, such as roofing seals, marine environments, or enclosures.
You need high-temperature or steam resistance, including HVAC or boiler gaskets.
Static sealing with excellent compression recovery is required.
You need dielectric insulation or high electrical resistance.
What Is Santoprene™ (TPV)?
Santoprene™ is a thermoplastic vulcanizate (TPV) that combines the elasticity of EPDM rubber with the processability of polypropylene. The material behaves like rubber but can be processed like plastic, allowing for rapid, recyclable, and cost-effective production.
Key properties of Santoprene (TPV):
Rubber-like flexibility with thermoplastic manufacturing advantages (extrusion, molding).
Resistance to weathering, UV, and many chemicals.
Recyclable and melt-processable, offering sustainability benefits.
Available hardness range of 35A–90A Shore, similar to many rubbers.
Can be colored and co-molded with rigid plastics for aesthetic or functional integration.
Because it can be injection molded, extruded, or co-molded with rigid plastics, Santoprene provides design flexibility that traditional rubbers cannot match. It is widely used in automotive boots, HVAC gaskets, consumer grips, and appliance seals.
When to Choose Santoprene (TPV)
Santoprene is ideal when flexibility, ease of processing, and cost-efficiency are priorities. Its thermoplastic nature makes it especially suitable for parts requiring frequent flexing, co-molding, or recyclability.
Choose Santoprene when:
The component must flex or move repeatedly during operation.
You need overmolded or co-molded parts (e.g., sealing to rigid plastic housings).
Cost and recyclability are key factors.
The part will be exposed to light oils, greases, or mild chemicals.
EPDM vs. Santoprene: A Detailed Comparison
| Property | EPDM Rubber | Santoprene (TPV) |
|---|---|---|
| Temperature Range | Performs reliably from −50°C to +150°C; excellent for sustained heat or cold exposure. | Typically stable up to 125°C continuous use; short excursions to 135–140°C. |
| UV / Ozone Resistance | Exceptional resistance to UV, ozone, and weathering; ideal for long-term outdoor applications. | Good resistance, though long-term UV exposure can cause slight surface degradation over time. |
| Chemical Resistance | Excellent resistance to water, steam, alcohols, and glycol-based fluids (e.g., coolants, brake fluids). | Better resistance to light oils, greases, and mild hydrocarbons due to its polypropylene phase. |
| Elastic Recovery | Maintains excellent compression recovery and elasticity over time; ideal for static gaskets. | Flexible but can take a compression set under high heat or prolonged deformation. |
| Recyclability | Non-recyclable; crosslinked structure prevents reprocessing. | Fully melt-processable and recyclable, reducing scrap and lifecycle cost. |
| Color & Aesthetics | Typically black; limited color options. | Can be colored or co-molded for aesthetic or branding requirements. |
| Adhesive / PSA Bonding | Variable surface chemistry; adhesion improves with primers and surface prep. | More difficult to bond due to low surface energy; surface treatment or primer often required. |
| Electrical Properties | Excellent dielectric insulation; used for electrical gasketing and enclosure seals. | Moderate dielectric performance; not typically used for electrical insulation. |
| Cost / Production Volume | Higher initial cost due to curing, but superior longevity in demanding environments. | Lower processing cost; preferred for high-volume, cost-sensitive applications. |
Adhesive and PSA Bonding Considerations
Both EPDM and Santoprene present challenges for pressure-sensitive adhesive (PSA) bonding due to their low surface energy and use of additives. Santoprene’s polypropylene phase makes adhesion particularly difficult without surface modification or priming.
EPDM formulations can vary in surface chemistry, and oils or fillers can migrate to the surface, weakening adhesive performance over time. Proper surface preparation—cleaning, abrasion, or priming—is essential for both materials.
To improve adhesion, surface preparation, including cleaning, abrasion, or priming, is typically necessary. At Engineered Materials, we test multiple adhesive systems (acrylic, silicone, or modified rubber) to ensure compatibility with the specific EPDM grades used in production.
We can help you whether your application requires EPDM or Santoprene materials.
How to Choose the Right Material
When deciding between EPDM and Santoprene, consider the following factors:
Operating temperature and exposure to heat or cold.
Chemical environment: water, oils, fuels, or coolants.
Environmental conditions: prolonged UV, ozone, or moisture exposure.
Flexing or static requirements of the part.
Manufacturing process: molded, extruded, or overmolded.
Adhesive compatibility and lamination requirements.
Desired service life and production volume.
Partner with Engineered Materials for Material Selection and Conversion
At Engineered Materials, we help design engineers and product developers navigate complex elastomer selection and bonding challenges. Our team evaluates every aspect of your design—from material performance and adhesive compatibility to converting methods such as multi-layer lamination, slitting, and precision die-cutting. Whether you need a static EPDM gasket for outdoor electrical enclosures or a flexible Santoprene seal for HVAC assemblies, our experts will ensure your component performs as engineered.
Contact Engineered Materials today to discuss your sealing or bonding challenge and discover how our converting expertise can help.