Rubber (Ethylene Propylene Diene Monomer) EPDM:
Ethylene-propylene rubber was first introduced in the United States in 1962 in small quantities. Between 1954 and 1960, small amounts of it were made in Italian and American laboratories. Although commercial production began in 1963, ethylene-propylene rubber now has the highest rate of growth.
History of EPDM:
The history of this rubber goes back to the history of the production of ethylene and propylene plastics. In 1951, German scientist Karl Ziegler (Karl Ziegler (1898-1973)) discovered a new group of polymerization reaction catalysts. These catalysts were composed of a sample of transition metal halogens along with an organic-metallic reducing agent such as alkyl aluminum. Ziegler catalysts were first used commercially in the manufacture of linear high density polyethylene at low pressure.
In Italy, Professor Giulio Natta (1903-1979) expanded the research on this type of catalysts and proved that some of them are capable of producing and creating many polymers that usually differ from other types in terms of spatial arrangement. have, are for this reason, these catalysts are called stereo specific catalysts. Nata also discovered that propylene could also be polymerized in this way, and as a result, polypropylene was marketed as the second olefin plastic.
Polyethylene and polypropylene are thermoplastics and do not have rubber or elasticity in any way. With the further progress of the studies, Nata found that by using some types of Ziegler catalysts, ethylene and propylene can be co-polymerized in an irregular and random manner and create an amorphous material with good elasticity and rubber properties.
In 1963, Ziegler and Nata were jointly awarded the Nobel Prize in Chemistry for their discovery that led to the creation of several new elastomers and plastics, including ethylene and propylene rubbers.
Ethylene, Propylene, Diene is a monomer, a copolymer of ethylene, propylene and a small amount of non-conjugated Diene monomers (3-9%) that provides cross-linking sites for vulcanization. which is called cross linking.
DN can usually be these three combinations:
Ethylidene nobornene (ENB)
Properties of EPDM:
EPDM elastomers have good resistance to heat, ozone, weathering and aging. Also, these rubbers are good electrical insulators and show good resistance against chemicals. EPDM is the most water resistance rubber. These tires have weak flame resistance.
Application of EPDM:
The largest EPDM market is in the automotive industry, which is used to produce parts such as radiator and heater hoses, door and window seals, o-rings and washers, accumulator bladders, wire and cable connections, insulators and diaphragms. The combination of EPDM with other polymers (eg PP) is used for car bumpers and fenders. The applicable temperature range of this rubber is from -45 to 150 degrees Celsius and it is used in steam up to 180 degrees Celsius.
Choosing the most suitable grade of this tire depends on the following characteristics:
1- Ethylene percentage: The usual ethylene percentages in EPDM chains are in the range of 40 to 70% by weight. As the percentage of ethylene increases, the mechanical strength of the grade increases, on the other hand, the hardness of the sample and its glass transition temperature also increase, but this point leads to a decrease in the EPDM softness performance.
2- Molecular weight: with the increase of molecular weight and its equivalent Mooney viscosity, its mechanical strength increases. Also, in this case, the compression set will be reduced.
3- The percentage of DN monomer: by increasing the weight percentage of DN monomer in the structure of EPDM, the curing speed of the final compound increases and on the other hand, the compression limit decreases.
De, S. K. (Sadhan K., White, J. R., & Rapra Technology Limited. (2001). Rubber technologist’s handbook. 576
Britannica, T. Editors of Encyclopaedia (2016, September 13). butyl rubber. Encyclopedia Britannica. https://www.britannica.com/science/butyl-rubber
Chandrasekaran, C. (2017). Rubbers Mostly Used in Process Equipment Lining. Anticorrosive Rubber Lining, 87–101. https://doi.org/10.1016/B978-0-323-44371-5.00012-8
Britannica, T. Editors of Encyclopaedia (2017, August 18). Ziegler-Natta catalyst. Encyclopedia Britannica. https://www.britannica.com/science/Ziegler-Natta-catalyst
Gavens, P. D., Bottrill, M., Kelland, J. W., & McMeeking, J. (1982). Ziegler–Natta Catalysis. Comprehensive Organometallic Chemistry, 3, 475–547. https://doi.org/10.1016/B978-008046518-0.00034