Ethylene-propylene-diene rubber

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Ethylene-propylene-diene rubbers ( abbreviation EPDM, E thylen- P ropylen- D ien; M ) group are terpolymers of ethylene , propylene and a not further specified diene . EPDM is one of the synthetic rubbers with a saturated main chain (according to DIN ISO 1629: M group ). Rubbers with an unsaturated main chain, such as. B. natural rubber or styrene-butadiene rubber , however, belong to the R group . EPDM rubbers have double bonds in the side chains and can therefore also be vulcanized with sulfur .

The rubber-elastic material EPDM is used in a wide variety of industries, e.g. B. for profiles in automobile and device construction, for conveyor belts, hoses for washing machines and dishwashers, seals in water fittings, for cable sheathing, etc. In buildings, EPDM waterproofing membranes are used to seal roofs and facades or as pond liner to seal liner ponds ( swimming ponds and Water basin).

designation

As a rule, the internationally common abbreviation EPDM is used for ethylene-propylene-diene rubber in everyday language . The M originally stands for rubbers of the M group according to DIN ISO 1629 with a saturated main chain. According to DIN ISO 1629, the designation of the different rubbers is based on the structure of their polymer structure. The last letter in the name describes the structure of its main chain, while the first letters give an indication of the monomer.

However, the reverse translation of the abbreviation EPDM as "ethylene-propylene-diene-monomer rubber" or shortened as "ethylene-propylene-diene monomer (s)" has also become commonplace, the latter is actually incorrect because EPDM is a polymer , but is often used.

history

The industrial production of EPDM began on a larger scale after chemists Karl Ziegler in Germany and Giulio Natta in Italy were able to improve and simplify the polymerization process for the development of complex plastics using special mixed catalysts ( Ziegler-Natta process ). This made it possible for the first time to produce synthetic rubber profitably. In 1963, the two scientists jointly received the Nobel Prize in Chemistry for their process development.

Since then, the material has been widely used wherever robust sealing materials resistant to UV, ozone, acids and mechanical loads are required. In 1968 the first flat roof in Europe was sealed with EPDM, which still works today.

Manufacturing

Production takes place with metallocene or Ziegler-Natta catalysts based on vanadium compounds and aluminum alkyl chlorides. As diene unconjugated dienes (dienes in which the information contained in the compound are double bonds are alternately performed with a single bond) is used, of which only one double bond is involved in the polymer chain formation, remain so that more double bonds outside the direct chain backbone, and, in contrast to ethylene - Propylene copolymer (EPM) can also be vulcanized with sulfur , while EPM can only be peroxide -crosslinked. Dicyclopentadiene (DCP), 1,4-hexadiene or ethylidene norbornene (ENB, IUPAC : 5-ethylidene-2-norbornene) are used as the diene component . The dienes differ in terms of the rate of crosslinking. DCP has the lowest, ENB the highest reactivity. With regard to costs, the order is reversed.

EPDM polymer, type Keltan from Lanxess , 200 grams
EPDM foil for sealing roofs

Properties and use

The molecular structure with a saturated main chain of EPDM leads to properties such as B. high weather and ozone resistance and high thermal resistance. Due to its good chemical resistance to polar media (media with a permanent dipole moment , i.e. uneven charge distribution in the molecule, such as water or alcohol), it is used for various seals such as B. O-rings are used in contact with water / steam, cooling liquids as well as acids and alkalis. The resistance to non-polar mineral oils or petrol, however, is poor (“like dissolves in like”).

EPDM is resistant to long-term aging, resistant to UV radiation and ozone, weather-resistant, robust, accessible, thermally resistant and frost-proof as well as easy and fire-proof in the building sector. Typical applications for the material EPDM are therefore among others: window seals or door seals on vehicles, brake and cooling water hoses, but also molded parts, sealing elements or conveyor belts in industrial production. Absorber mats, which are resistant to water containing chlorine , for heating swimming pools as well as high-quality pond liners are made of EPDM. It is particularly suitable for this purpose because it is highly flexible, UV- resistant and also durable, even in the cold . EPDM is also used in household appliances such as washing machines and dishwashers and as seals in water fittings. Due to its high UV and ozone resistance, EPDM is suitable for permanent outdoor use. A large area of ​​application are still high-quality waterproofing membranes or tarpaulins for new buildings or renovations in the building sector, e.g. B. for flat roofs, facades and building waterproofing . Another typical application of EPDM membranes is elastic low-pressure gas storage in biogas plants.

Commercially available EPDM rubber types

Today, the material is manufactured in different variants (structure, layer structure, additives, etc.) for different needs and purposes. The type and quantity of the components used change the mechanical properties and the vulcanization behavior of the polymer.

Commercially available EPDM rubbers have an ethylene content of 45-75% by weight. Polymers with a low ethylene content (45-55 wt%) are amorphous and have the best low-temperature flexibility. With increasing ethylene content, the crystallinity increases (pure linear polyethylene is highly crystalline). An EPDM with a medium ethylene content (55-65% by weight) is partially crystalline. Terpolymers over 65 wt% ethylene have larger crystalline areas and therefore behave like thermoplastic elastomers; these already have a high tear strength in the non-crosslinked state .

The diene content of commercial products is 0 (EPM) –12% by weight, corresponding to a proportion of 0–16 double bonds per 1000 carbon atoms. A higher diene content results in a higher crosslinking rate, higher strengths and less permanent deformation (compression set). The aging and weathering resistance, however, decreases with increasing diene content.

sustainability

EPDM is considered a material that only has a minor impact on the environment during production, processing and use. It does not contain any volatile plasticizers or pollutants that could be released over the service life. So recommends z. B. the BUND as an alternative to PVC -containing garden hoses "garden hoses made of the ecological substitute material ethylene-propylene-diene rubber (EPDM for short)". A key sustainability feature is the material's long service life. B. in the building sector improves the overall eco-balance compared to other materials. The material can be reprocessed and e.g. B. used for floor coverings or thermally recycled.

further reading

Web links

Wiktionary: Ethylen-Propylen-Dien-Kautschuk  - explanations of meanings, word origins, synonyms, translations
Wiktionary: EPDM  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ Christian Hopmann , Walter Michaeli : Introduction to plastics processing . Carl Hanser Verlag, 2017, ISBN 978-3-446-45484-2 , pp. 231 ( scan in Google Book Search [accessed November 1, 2019]).
  2. ↑ EPDM climbed onto the roof - EPDM. In: epdm-dach-fassade.de. Retrieved November 1, 2019 .
  3. ↑ Sealing flat roofs: you need to know that. In: haus.de. Retrieved November 1, 2019 .
  4. ↑ EPDM - The stuff the future is made of. - EPDM. In: epdm-dach-fassade.de. Retrieved November 1, 2019 .
  5. ↑ 50 years of EPDM - EPDM. In: epdm-dach-fassade.de. Retrieved November 1, 2019 .
  6. ↑ a b c d ethylene-propylene rubber, ethylene-propylene-diene rubber. (PDF; 476 kB) In: materialarchiv.ch. Educational Network Material Archive, June 11, 2019, accessed on November 1, 2019 .
  7. ↑ EPDM - Society for Roof and Facade - EPDM. Retrieved November 1, 2019 .
  8. ↑ Georg Abts: Introduction to rubber technology . 2nd, revised edition. Carl Hanser Verlag, Munich 2019, ISBN 978-3-446-45461-3 , urn : nbn: de: 101: 1-2018122218223372300655 .
  9. ^ Stephan Engelsmann, Valerie Spalding, Stefan Peters: Plastics in architecture and construction . Birkhäuser, Basel 2012, ISBN 978-3-0346-0321-8 , p. 66 , urn : nbn: de: 101: 1-2016060311257 ( preview in Google book search [accessed November 1, 2019]).
  10. ↑ RADO Gummi GmbH: EPDM. Retrieved November 1, 2019 .
  11. ↑ Environmental Responsiveness. In: epdmroofs.org. Accessed November 1, 2019 .
  12. ↑ a b Recyclage. In: Verenigde EPDM Systeem Producenten. Retrieved November 1, 2019 (French, Dutch).
  13. ↑ Irrigation without poison. Retrieved December 8, 2019 .
  14. ↑ NIBE. In: Verenigde EPDM Systeem Producenten. Retrieved November 1, 2019 (French, Dutch).