EPDM is widely used in automotive sealing and high-grade doors and Windows industry. Epdm sealing rubber strip has good ozone resistance, heat resistance, weather resistance and low softness. Can be used for ozone resistance, weather resistance, uv resistance and other occasions. But based on its own structural characteristics, its flame retardant, oil resistance and adhesion is poor. This kind of rubber has the main chain saturated structure, can blend, can learn from each other. The main chain of EPDM is composed of chemically stable saturated hydrocarbons, and the side chain contains only unsaturated double bonds, which is basically a kind of saturated rubber. Due to the lack of polar substituents in the molecular structure, the intermolecular binding energy is low, so the molecular chain remains flexible over a wide temperature range. The chemical structure of EPDM gives its vulcanized products unique properties.
1, low density and high filling: EPDM rubber is a kind of low density rubber, its density is 0.87. In addition, can also fill a large number of oil, add filler, reduce the cost of rubber products, make up for the original epDM rubber high price shortcomings. In addition, for EPDM with high Menoni value, the physical and mechanical properties of high filled EPDM do not significantly decrease.
2, aging resistance: epDM rubber has excellent weather resistance, ozone resistance, heat resistance, acid and alkali resistance, water vapor resistance, color stability, electrical performance, oil filling and room temperature liquidity. EPDM products can be used for a long time at 120℃, and can be used for a short time or intermittently at 150-200℃. Adding the right antioxidants can raise the temperature of use. Epdm crosslinked with peroxide can be used in even harsher conditions. When the ozone concentration is 50×10 ~, the tensile strength is 30% and the fracture time is less than 150 hours.
3. Corrosion resistance: due to the lack of polarity and low saturation of ethylene-propylene rubber, it has good corrosion resistance to various polar chemicals, such as alcohol, acid, alkali, oxidant, refrigerant, detergent, animal and vegetable oils, ketone, grease and so on; But in aliphatic and aromatic solvents (such as gasoline, benzene, etc.) and mineral oils. Performance is also degraded under the long-term action of concentrated acid. In ISOtr7620, data are collected on the effects of nearly 400 corrosive gases and liquid chemicals on various rubber properties. There are more than 80 kinds of chemicals with a degree of ethylene propylene rubber, here is not a list.
4, water vapor resistance: epDM rubber has excellent water vapor resistance and excellent heat resistance. In 230℃ superheated steam, after nearly 100 hours, no change in appearance. Under the same conditions, the appearance of fluorine rubber, silicone rubber, fluorine silicone rubber, butyl rubber, nitrile rubber and natural rubber deteriorated obviously in a short time.
5, heat resistance: epDM rubber heat resistance is also good, but is closely related to the vulcanization system used. The mechanical properties of dimorpholine dithiocarbamate and TMTD vulcanized ETHYLENE propylene rubber changed little after 15 months of 125℃ superhot water soaking, and the volume expansion rate was only 0. Electrical properties: EPDM has excellent electrical insulation and corona resistance, its electrical properties are better than or close to styrene butadiene rubber, chlorosulfonated polyethylene, polyethylene and crosslinked polyethylene.
6, elasticity: epDM molecular structure without polar substituents, molecular cohesion is low, molecular chain can maintain flexibility in a wide range, second only to natural rubber and butadiene rubber, can still maintain flexibility at low temperature.
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