Elastomers

NR - NATURAL RUBBER

Natural Rubber is obtained from the robber tree. Of the many existing species, only 'Hevea Brasiliensis', which originated in the Amazan region is commercially exploited. Because of its natural origin, it is not a homogenous product, but even so it is classified in different grades according to the visual and analytical evaluation criteria.

• Excellent mechanical properties, such as resistance against stretchingand tearing, and elasticity.
• Wide range of hardnesses, from 35 to 90 Shore A.
• High elasticity, excellent dynamic properties and low compression set.
• Excellent electrical properties.
• Sensitive to ozone . Resistance against atmosferic conditions can be improved bu adding antiozonants combined with waxes.
• Temperature range is in between -50°C to -90°C.

SBR - STYRENE BUTADIENE RUBBER

More than half of the synthetic rubber produced in the world is SBR. SBR contains approximately % 23 of styrene. Any increase in this content leads to the deterioration of its properties such as elasticity and resistance against low temperatures while at the same time increasing hardness.

• They require reinforcing fillers to attain good mechanical properties, and by doing so, can achieve higher corrosion resistance than natural rubber.
• Similar to natural rubber but better ageing and heat resistance.
• Lower flexibility compared to natural rubber.
• Moderate resistance against tearing, ozone and atmosferic conditions.
• Temperature range is in between -50°C to -110°C.

CR - CHLOROPRENE RUBBER (NEOPRENE)

lt offers the most balanced set of desirable properties. The chlorine atom increases the level of resistance against oils, placing it between natural nubber and nitrite rubbber.

Properties

• Excellent corrosion resistance and mechanical properties.
• Has lower flexibilty than natural rubber in low rigidities, but higher in 60 Shore A + rigidities.
• Presents good resistancce against heat and ozone.
• Flame retardant.
• Good adhesion to metal.
• Temperature range is in between -25°C to -125°C.

NBR - NITRILE RUBBER

Depending on the acrylonitrile content (ACN), they can be classified as Low ACN ( 18-24%), Medium ACN ( 34%) and High ACN ( 50%) content. By increasing the ACN content:

• Resistance against oil and fuels increases.
• Resistance against stretching, corrosion and heat, rigidity and sealing properties increase.
• Flexibility values under low temperatures decrease.

Properties

• Resistant against oils and can be formulated for applications requiring heat.
• Good mechanical properties.
• lmpermeable against gas.
• Ageing is moderate.
• Good adhesion to metal.
• Moderate resistance for low temperatures, however, with adequate use of plastffiers, it can be used in applications of -40°C.
• Temperature range is in between -30°C to -120°C.

EPDM - ETHYLENE RUBBER

The copolymers of Ethylene and Propylene (EPM) can only be vulcanized by peroxides or radiation,whereas by adding Diene (EPDM) it is possible to achieve conventional vulcanization with sulphur, thereby increasing their resistance to tearing.

Properties

• Excellent resistance against ageing, ozone, ultraviolet light, and atmosferic conditions.
• Excellent electrlcal properlies and radiation stability.
• Moderate adhesion to metal.
• Temperature range is in between -40°C to -120°C. Can also be formulated for continues services at 140°C.

CSM - CHLOROSULPHONATED POLYETHYLENE RUBBER

Properties

• Excellent oxidation; resistance against ozone and atmosferic conditions.
• Excellent resistance against hydrocarbonated solvents.
• Resistant against flames.
• Moderate adhesion to metal.
• Temperature range is in between -35°C to -140°C.

VMQ - SILICONE RUBBER

Unlike other synthetic rubbers, its moleculsr chain does not contain carbon; it only consists of silicone and oxygen atoms.

Properties

• Has perfect heat resistance (200°C - 220°C) in dry environments. In contact with high pressurised steam (130°C - 140°C ) or in case of ageing in closed systems without the presence of oxygen, degradation by hydrolsis may occur.
• Absolutely unalterable by ozone, atmosferic conditions or ultraviolet radiation.
• Has good insulation properties.
• Self-extinguishable. The residue (silica), which originates from complete combustion by prolonged contact with flames, is an excellent electrical insulator.
• Physically inert, hence suitable for medical applications.
• Temperature range is in between -70°C to -220°C.

FKM - FLUOROCARBONATED RUBBER

They are known as fluorelastomer rubbers. Their resistance against chemicals and low /high temperatures is directly propotional to their fluorine content.

Properties

• Resistant against extremely high temperatures. 250°C in continuos running and 300°C in intermittent running.
• Has extraordinary chemical resistance in high temperatures.
• Self-extinguishable.
• Has low deformation in high temperatures.
• The low temperature range is between -30°C and -50°C.

CO/ECO - EPICHLOROHYDRIN RUBBER

Properties

• Has excellent resistance against ozone and weather conditions a saturated polymer.
• COs withstand continuous service temperatures of up to 150°C and are fragile from -23°C.
• ECOs and ethers can support continuous service temperatures of up to 135°C, and maintain their flexibility above -40°C.
• Resistant against flames.
• Has excellent elastic properties.