EPDM Rubber Introduction

by Dongrubber on October 16, 2006 · 0 comments

EPDM main chain is saturated, and the side of the base is not saturated, therefore it is available sulfured by vulcanization accelerator. The raw material of rubber is using solution polymerization system (suspension), produced through the coordination anion addition polymerization.

1. The characteristics of EPDM rubber

Because ethylene propylene rubber is propylene for amorphous, destroyed the original PE crystalline, thus it become non-crystalline irregular copolymer rubber, and reserves some characteristics of polyethylene at the same time. While EPDM rubber introduced a small amount of unsaturated group, but it is still on the double bond in the side chain, therefore, on the basic properties there’s no much difference.

Because EPDM rubber basically is a kind of saturated polymer compound, there’s not substituent polarity within molecules, link is smooth.

2. The advantages of EPDM rubber

Compared to other rubber, it has the following five advantages:

(1)Excellent resistance to aging performance is the best in the existing general rubber.

① Ozone resistance. In the medium containing ozone 1m/kg, 2430h EPDM rubber is still not cracked, but generally think the best aging resistance butyl rubber only can last 534h then produce big fissure, neoprene is only 46h. Under the 30% ozone concentration, neoprene 7min have crack, and EPDM rubber after 1h there is still no change.

② The climate resistance. In the sunlight, EPDM rubber sheet 3 years no crack; Styrene-butadiene rubber 5d tears, 70d fracture; Natural rubber 150 d there is big gap.

③ Heat aging. Generally can be used for a long time at 150 ℃ temperatures, resistant of intermittent use can reach 200 ℃, the mechanical properties change slowly.

(2) Excellent electric insulation. Better than the butyl rubber, especially its corona resistance is outstanding,

Generally butyl rubber is around 2h, while EPDM rubber can reach more than 2 months, and because of EPDM rubber absorbent is small, so after flooding its electrical resistance is still very good

(3) Good chemical resistance. To various chemicals and acids, alkalis polarity has greater resistance tolerance, after long time contact with little change in performance. But for hydrocarbon oil its stability is poorer, in the strong acid after a long time, its mechanical performance declined.

(4) Impact resilience is better. It can be up to 50% – 60%, which is secondly only to butadiene rubber and natural rubber. Especially because of it is no crystalline, under low temperature condition it keep good elasticity, frozen until – 57 ℃ to harden, to – 77 ℃ brittle.

(5) Can be carried out to cooperate with high fill. Density is small, and can be mixed with a large number of filler and oils. Cooperate in the high fill during the process of production, but performance degradation very little.

3. The disadvantage of EPDM rubber

The main disadvantage of EPDM rubber is as follows:

(1) The vulcanization rate is low. Synthetic rubber is 66%-75% lower than normal, so when use with other high unsaturation rubber its total sulfur and total soluble is poor, makes the mechanical properties decreased significantly.

(2) The self viscosity and mutual viscosity is very poor. Not easy bonding, which brings great difficulty to processing technology.

4. The basic characteristic of the EPDM rubber

(1) The density of EPDM rubber sheet is small (0.85-0.86g/cm), it still has the binary ethylene-propylene rubber ozone resistance, weatherability, heat resistance and chemical resistance and other properties.

(2) Can use sulfur vulcanization accelerator vulcanization system, also can use organic peroxide crosslinking, to produce high strength products.

(3) Good low temperature resistance, electrical insulation performance.

(4) Contain high amount of fillers and the oils bear ability when cooperated.

(5) Can be used with unsaturated rubber, and the low unsaturated rubber and plastic.

(6) Because its apparent vulcanizates quality is good, and also with high physical properties, it is suitable for the production of foam products.

(7) Poor adhesion for unvulcanized rubber.

5. The application of EPDM rubber

EPDM rubber usage is very extensive, it besides cannot serve as tire tread rubber, in the industrial, life, etc have important applications in many areas. It is mainly used in automobile industry, wire and cable industry, construction and waterproof materials, rubber products, civilian products, and other rubber or resin and or blending, also can be used as additive, etc.

(1) It is light and color is shallow, it can manufacture light color products, such as rubber shoes, health supplies, etc.

(2) Its good electrical insulating performance and ability against high temperature, so it can be used as the cover of wire, cable and other high pressure, ultra-high voltage electrical insulation materials.

(3) Good aging resistance and excellent water resistance, it can be used as the dam, the pond substrate, bridge rail pad, and other building materials.

(4) Good resistance to water and water vapor properties, so it can be used to make steam hose.

(5) Can be used as the car storm strip, water tank hose, heater hose, and basked in the hood, sealing materials, etc. At present, the consumption for EPDM rubber used in automobile parts accounts for about 30% to 40% in total.

(6) EPDM, though it is not used as tire tread rubber, but can be used as a tire sidewall, gaskets and inner tube. Adding 20% EPDM in butyl rubber, for example, the automobile inner tube both maintained a good air tightness, and improve the inner tube heat resistance; Adding 25% EPDM in natural rubber of white tire of the car, is both practical and economy; Adding 25% in neoprene  car tire, its abrasion resistance, aging resistance were increased.

(7) EPDM rubber can be blended with other rubber or resin, so as to improve some performance of the rubber and resin. For example, it is added to pp, ABS resin, polystyrene, polyvinyl chloride (PVC), which can improve the impact resistance, resistance to scratching and tearing resistance performance; NBR blending EPDM, its ozone resistance can be improved.

Low relative molecular mass of Ethylene-Propylene-Diene Monomer can be used as a new type of oil thickener. It not only has good thickening ability, also is more safety and has good oxidation, ultrasonic shear stability and exhaust gas cleaness.

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