3/9/2011
( Phần 1)
( Phần 1)
Properties and Applications
Ethylene-propylene rubbers & elastomers (also called EPDM and EPM) continue to be one of the most widely used and fastest growing synthetic rubbers having both specialty and general-purpose applications. Sales have grown to 870 metric tons (or 1.9 billion pounds) in 2000 since commercial introduction in the early 1960’s. Polymerization and catalyst technologies in use today provide the ability to design polymers to meet specific and demanding application and processing needs. Versatility in polymer design and performance has resulted in broad usage in automotive weather-stripping and seals, glass-run channel, radiator, garden and appliance hose, tubing, belts, electrical insulation, roofing membrane, rubber mechanical goods, plastic impact modification, thermoplastic vulcanizates and motor oil additive applications.
Ethylene-propylene rubbers & elastomers (also called EPDM and EPM) continue to be one of the most widely used and fastest growing synthetic rubbers having both specialty and general-purpose applications. Sales have grown to 870 metric tons (or 1.9 billion pounds) in 2000 since commercial introduction in the early 1960’s. Polymerization and catalyst technologies in use today provide the ability to design polymers to meet specific and demanding application and processing needs. Versatility in polymer design and performance has resulted in broad usage in automotive weather-stripping and seals, glass-run channel, radiator, garden and appliance hose, tubing, belts, electrical insulation, roofing membrane, rubber mechanical goods, plastic impact modification, thermoplastic vulcanizates and motor oil additive applications.
Heat aging resistance up to 130°C can be obtained with properly selected sulfur acceleration systems and heat resistance at 160°C can be obtained with peroxide cured compounds. Compression set resistance is good, particularly at high temperatures, if sulfur donor or peroxide cure systems are used.
These polymers respond well to high filler and plasticizer loading, providing economical compounds. They can develop high tensile and tear properties, excellent abrasion resistance, as well as improved oil swell resistance and flame retardance. A general summary of properties is shown in Table I below.
Table 1. - Properties of Ethylene-Propylene Elastomers
These polymers respond well to high filler and plasticizer loading, providing economical compounds. They can develop high tensile and tear properties, excellent abrasion resistance, as well as improved oil swell resistance and flame retardance. A general summary of properties is shown in Table I below.
Table 1. - Properties of Ethylene-Propylene Elastomers
Polymer Properties
Mooney Viscosity, ML 1+4 @ 125°C 5-200+
Ethylene Content, wt. % 45 to 80 wt. %
Diene Content, wt. % 0 to 15 wt. %
Specific Gravity, gm/ml 0.855-0.88 (depending on polymer composition)
Vulcanizate Properties*
Hardness, Shore A Durometer 30A to 95A
Tensile Strength, MPa 7 to 21
Elongation, % 100 to 600
Compression Set B, % 20 to 60
Useful Temperature Range, °C -50° to +160°
Tear Resistance Fair to Good
Abrasion Resistance Good to Excellent
Resilience Fair to Good (stable over wide temp. ranges)
Electrical Properties Excellent
* Range can be extended by proper compounding. Not all of these properties can be obtained in one compound.
Producers
Major producers and suppliers of EPDM and EPM are Bayer Polymers, Crompton Corp., Exxon-Mobil Chemical Co., DSM Elastomers, Dupont Dow Elastomers, Herdillia, JSR, Kumho Polychem, Mitsui Chemicals, Polimeri Europa, and Sumitomo Chemical Co. Wide ranges of grades are available worldwide to provide solutions to many product requirements.
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