EPDM (Ethylene Propylene Diene Monomer) is a widely used synthetic rubber with the following characteristics:
Chemical Structure
Backbone: Saturated carbon chain composed of ethylene (C₂H₄) and propylene (C₃H₆), providing excellent aging resistance.
Side Chains: Diene monomers (e.g., ENB, DCPD) offer crosslinking sites for vulcanization, structural formula: −(CH₂-CH₂)�−(CH₂-CH(CH₃))�−−(CH₂-CH₂)x−(CH₂-CH(CH₃))y−.
Key Properties
Temperature Resistance: -50°C to 150°C (continuous use), short-term tolerance up to 180°C.
Weather Resistance: Resists UV, ozone, and oxidation, with outdoor service life exceeding 20 years (e.g., roofing membranes).
Electrical Insulation: Volume resistivity >10¹⁵ Ω·cm, suitable for high-voltage cable insulation.
Water Resistance: Water absorption <0.5% (ASTM D570 test).
Applications
Automotive: Door seals, radiator hoses (resistant to coolant ethylene glycol).
Construction: Bridge expansion joint sealants, curtain wall gaskets (UV-resistant).
Energy: Solar panel frame seals (tolerates high temperature and humidity).
Comparison with Other Materials
| Property | EPDM | NBR | Silicone |
|---|---|---|---|
| Temp. Range | -50~150°C | -30~120°C | -60~230°C |
| Oil Resistance | ★☆☆☆☆ | ★★★★★ | ★★☆☆☆ |
| Cost | Medium ($5~10/kg) | Low ($3~6/kg) | High ($20~50/kg) |
Limitations
Poor Oil Resistance: Unsuitable for fuel/lubricant exposure (swelling rate >50%).
Complex Vulcanization: Requires peroxide or sulfur curing systems, with longer processing times.