1. Basic Properties of EPDM

Ethylene Propylene Diene Monomer (EPDM) is a type of synthetic rubber made from the copolymerization of ethylene, propylene, and a small amount of non-conjugated diene. Its unique molecular structure gives EPDM various excellent physical and chemical properties, making it an ideal material for manufacturing high-performance seals.

1. Weather Resistance

EPDM has outstanding resistance to ultraviolet light and weather aging. Even after prolonged exposure to outdoor environments, EPDM seals can maintain their elasticity and sealing performance, showing little degradation or brittleness.

2. Weatherability

EPDM can maintain stable physical and chemical properties over a wide temperature range (-50°C to 150°C), demonstrating excellent weatherability. This makes it suitable for use in extreme temperature conditions.

3. Ozone Resistance

EPDM has a very high resistance to ozone, making it less prone to cracking and degradation. This property allows it to perform excellently in outdoor and harsh weather conditions.

4. Electrical Insulation

EPDM has excellent electrical insulation properties, providing reliable protection in electrical equipment and cable seals, ensuring the safe operation of devices.

5. Chemical Resistance

EPDM has good resistance to various chemicals (such as water, acids, and bases), but it may swell or dissolve in certain polar solvents (such as ketones and esters).

2. Manufacturing Process of EPDM Seals

The manufacturing process of EPDM seals involves several key steps and techniques to ensure that the final product has excellent performance and reliability.

1. Raw Material Preparation

Selection of raw materials:

• Ethylene, propylene, and non-conjugated diene (such as dicyclopentadiene).
• Various additives, such as vulcanizing agents (sulfur or peroxides), antioxidants, fillers (carbon black, silica), plasticizers, lubricants, etc.

2. Mixing

Internal mixing or open mixing:

• The EPDM raw rubber is mixed with various additives in an internal mixer or open mill to ensure even distribution of components.
• Control the temperature and shear force during mixing to avoid overheating or excessive shear that could degrade material performance.

3. Extrusion Molding

Calendering or extrusion:

• The mixed EPDM compound is formed into the preliminary shape of O-rings through a calender or extruder.
• Control the extrusion speed and temperature to ensure the accuracy of cross-sectional shape and dimensions.

4. Vulcanization Treatment

Vulcanization oven or autoclave:

• The molded EPDM seals are placed in a vulcanization oven or autoclave for vulcanization under high temperature and pressure conditions.
• The vulcanization conditions (temperature, time, and pressure) depend on the specific rubber formulation and product requirements. Typically, vulcanization temperatures range from 150°C to 200°C, with vulcanization times varying from a few minutes to several hours.

5. Post-Processing

Cooling and trimming:

• The vulcanized EPDM seals are cooled rapidly through a cooling water tank.
• Trimming of the vulcanized seals is performed using a trimming machine or grinder to remove burrs and excess material, ensuring dimensional accuracy and surface quality.

6. Testing and Packaging

Performance Testing:

• Various performance tests are conducted on EPDM seals, such as hardness testing, tensile strength testing, ozone resistance testing, and compression set testing.
• Seals that meet the requirements are packaged to prevent damage during storage and transportation.