The compounding ingredients used to improve the physical properties of the final rubber product and to get the cost effective compounds are called fillers. All types of fillers generally used in rubber industry are available for EP(D)M. Though it varies more or less by the molecular weight, ethylene content, and diene content, lots amounts of fillers can be added to EP(D)M synthetic rubber compared with other types of syntetic rubbers.

Vulcanization of EP(D)M Synthetic Rubber

Vulcanization is primarily a cross-linking process in which chemical bonds or bridges are formed between adjacent polymer chains by combining with sulfur or other additives in the pressnce of heat. This irreversble process improves the strength and resilience of the compound and imparts greater dimensional stability.
Also these vulcanizate becomes more resistant to swelling if organic fluids. When high molecular chains form crosslinks, it becomes 3-dimensional network structure as shown below.

CARBON BLACK Characteristic factor

- SULFUR VULCANIZATION : the most common crosslinking method of EP(D)M synthetic rubber
- PEROXIDE CURE : suitable for products requiring superior heat resistance and compression set
- RESIN Vulcanization : POLYHALOMETHYLENE resin is used for special products requiring heat resistance

Processing Method of EP(D)M Synthetic Rubber

The processability of EP(D)M synthetic rubber is basically determined by following parameters, which have to be considered when designing rubber compound.

POLYMER Structure and Type

- Molecular Weight
- Molecular Weight Distribution
- ETHYLENE / PROPYLENE Composition Distribution
- ENB Content
- Phsical Form of Product : DENSE BALE, FRIABLE BALE, PELLET, CRUMB

Contents & Structures of Fillers

Types & Contents of Processing

• EP(D)M MIXING
• EXTRUSION
• MOLDING
• CALENDING

General INTERNAL MIXER

Mixing of EP(D)M Synthetic Rubber

The aim of mixing is to obtain a homogeneous dispersion of organic/inorganic fillers, process olis, and polymers.

INTERNAL MIXING

INTERNAL MIXINGis the most common method to obtain uniform mixing of rubber compound. it is possible to obtain very good dispersion through the internal mixing

Typical INTERNAL MIXING Methods

MILL MIXING

The low to intermediate Mooney and oil-extended EPDM can be mixed on the open mill. The following grades are especially recommended for open mill mixing
- KEP210, KEP7141, KEP240, KEP330, KEP960(F) à KEP960N(F) - KEP2320

EXTRUSION

At first, the rubber extrusion was applied in tire tube, and today it is widely used in interior & exterior materials for automobiles, construction materiats, hoses, and cables. Especially, EPDM extrusion products require excellent surface, good collapse resistance, fast cure and etd. To manufacture the extrusion profile salisfying with the processing secification such as extrusion speed, die swell, dimensional stability, surface appearance of the extruded products and feeding, polymer and fillers should be carefully selected.

EXTRUSION 표

	MOONEY viscosity lncrease	ETHYLENE Content Increase	MWD broadened
Extrudability
Extrusion Feed
Extrusion Speed
Extrusion Surface
DIE SWELL
GREEN Strength
Collapse resistance

Increase of Good

Decrease or Bad

Little Influence

MOLDING

EP(D)M Synthetic Rubber can be made into various products by molding process

Genral MOLDING process

- COMPRESSION MOLDING
- INJECTION MOLDING
- TRANSFER MOLDING

Each moding process requires differentiated compound characteristics. All the KEP EP(D)M products can be applied with molding process. Especially. low Mooney viscosity products are suitable for complicated shape transter of injection mold due to their gool flow properties. In addition, varous protector sponge applied with EP(D)M can be produced by molding. Selection of the most suitable EP(D)M Grade in accordance with the characteristics of the rubber parts and process conditions are important.