Ethylene propylene diene monomer (EPDM), as a high-performance synthetic rubber, relies heavily on its filler system for its material properties. In recent years, the blending technology of silica and carbon black has demonstrated significant advantages in EPDM applications, becoming a hot research topic in the industry. The following systematically analyzes the latest development trends of this blending technology from multiple perspectives.

Performance Advantages of Blending Technology
The blending of silica and carbon black in EPDM achieves complementary properties and synergistic effects:

Improved Mechanical Properties:
Carbon black provides excellent reinforcing effects, significantly improving tensile strength and abrasion resistance.
Silica improves tear strength and cut resistance, especially with better adhesion to metals/fibers.
The tensile strength of the blended compound can reach 20.4 MPa, and the tear strength 95 kN/m.

Optimized Processing Performance:
Silica improves the flowability of the compound, reducing energy loss during extrusion.
Carbon black enhances the strength of the compound and ensures feeding stability.
The extruded surface of the blended compound is good, with clear edges.

Improved Special Properties:
Silica reduces rolling resistance and improves grip.
Carbon black enhances electrical conductivity and antistatic properties.
The blended system can balance weather resistance, heat resistance, and electrical insulation.

Blending Ratio and Process Technology
Typical Blending Ratio
Application Areas
Silica Ratio
Carbon Black Ratio
Total Filler
Performance Characteristics
Automotive Sealing Strips
30-50%
50-70% 20-70 parts: Ozone resistant, low compression set
Wires and cables: 40-60% 40-60% 30-60 parts: Good insulation, excellent flame retardancy
Industrial products: 20-40% 60-80% 40-80 parts High strength, high wear resistance

Note: The proportion is calculated based on the total weight of the filler and needs to be adjusted according to the grade.
Key Process Parameters

Mixing Process:
* Internal mixer mixing: Temperature 150℃, Pressure 10MPa, Time 5 minutes
* Open mill mixing: Roll gap 1.5-2.5mm, Roll temperature 50±5℃
* Segmented mixing: Add carbon black and silica first, then add the vulcanization system.

Dispersion Control:
* Use silane coupling agent to improve silica dispersibility
* Add 2-4 parts ethylene glycol to adjust the pH of silica
* Use high-shear mixing equipment to ensure uniform dispersion

Vulcanization System Matching:
* Sulfur vulcanization system: 1-2 parts sulfur, 0.5 parts accelerator CZ
* Peroxide vulcanization: DCP 2-3 parts, avoid reaction with silica

Resin vulcanization: Brominated alkylphenol resin, good heat resistance
Application Cases and Industry Practices
Automotive Sealing Strips: A case study shows that optimized filler compounding reduced costs by 12%. Compression set was optimized from 25% to 18% (100℃×70h). Ozone resistance met standards, extending service life.

Green Tires: Silica reduces rolling resistance and improves fuel efficiency. Carbon black enhances wear resistance and extends tire life. Compounded tread wet grip performance is improved by more than 15%.

Wires and Cables: Silica content is 40-60% for optimal insulation performance. Carbon black added in small amounts (2-5 parts) only as a colorant.
Suitable for medium and high voltage insulation applications.

Future Development Trends:
High Performance Direction:
Development of high-sulfurization-rate EPDM-specific materials
Research and development of high-flame-retardant EPDM composite materials
Development of new materials such as EPDM/chlorinated polyethylene alloys

Green and Environmentally Friendly Trend:
Use of bio-based fillers such as rice husk-based silica
Development of low-VOC formulations to reduce environmental pollution
Improvement of filler utilization rate in recycled EPDM

Process Innovation:
Replacing traditional processes with gas-phase polymerization
Research and development of high-end products such as metallocene EPDM
Application of intelligent mixing and online detection technologies