Hardness Comparison Table

Hardness Comparison Table

Physical Properties of Elastomer Compounds

Resistance Chart – Low Temperature

Classification of elastomers by heat and oil resistance

Resistance Chart – High Temperature

Classification of elastomers by heat and oil resistance

1.0 Nitrile Butadiene Rubber (NBR)

Elastomers are polymeric materials that can be stretched at room temperature to at least twice their original length and return almost to their original state when the force is removed. Rubbers are polymers that are not crosslinked but can be crosslinked, i.e., vulcanized. At high temperatures and under deforming forces, they show viscous, liquid-like flow, so they can be shaped under optimum conditions. Shaped elastomer materials display both viscous and elastic...

1.1 Natural Rubber (NR)

Natural rubber is obtained from the Hevea brasiliensis tree, which grows in high-rainfall tropical regions. It is an isoprene polymer that, once vulcanized, offers high strength and flexibility but low heat resistance. Its regular structure gives it a high degree of crystallization. This improves its physical properties but also causes hardening during storage and high heat build-up during mixing. Because of its high mechanical properties, it is preferred for vibration...

1.2 Ethylene Propylene Diene Rubber (EPDM)

EPDM is a polymer of ethylene, propylene and a small amount of diene. The diene group allows blending with other polymers and permits sulfur vulcanization as well as peroxide curing. EPDM seals are preferred in washing machines, dishwashers and sanitary fittings, and EPDM is also used in hydraulic systems with HFC/HFD fire-resistant fluids and with hydraulic brake fluids. It has very good resistance to hot water, steam and ozone, good resistance to heat, light and oxidation,...

1.3 Polyacrylate Rubber (ACM)

Polyacrylate is a polymer containing ethyl acrylate or butyl acrylate. ACM offers better heat resistance than NBR and is preferred mainly where NBR seals fall short at high temperatures, and for use with additive-containing oils. Its resistance to outdoor aging and ozone is very good. It has good swelling resistance to mineral oils and their additives (engine, gearbox and transmission oils). It is unsuitable for aromatic and chlorinated hydrocarbons, alcohols, brake fluids,...

1.4 Ethylene Acrylic Rubber (AEM)

AEM, the other acrylic-based elastomer, is a polymer of ethylene and methyl acrylate with a carboxyl group. It can be used over a wider temperature range than ACM and HNBR and has better heat resistance than ACM, so it retains its properties longer at high temperatures. It shows good swelling resistance to additive-containing mineral oils, paraffin, water and coolants, but poor resistance to transmission fluids, aromatics, brake fluids and acids. Recommended range: -40 °C to...

1.5 Polyurethane (PU)

Polyurethane is a polymer formed by the reaction of an isocyanate with an alcohol (polyol). It is a high-molecular-weight polymer whose chemical composition is defined by its urethane groups, and it shows its characteristic properties within certain temperature limits. It offers high tensile, tear and abrasion strength; very good weathering and ozone resistance; resistance to mineral oils, greases, water, water–oil mixtures and aliphatic hydrocarbons; low gas permeability;...

1.6 Fluoroelastomer (FKM)

FKM is a synthetic elastomer with fluorine atoms on its main or side chains. The high bond energy of its C–F bonds (451 kJ/mol) makes it highly resistant to heat and many chemicals. It is produced as a copolymer, terpolymer or tetrapolymer, mainly from vinylidene fluoride (VDF) combined with hexafluoropropylene (HFP), tetrafluoroethylene (TFE) and perfluoromethyl vinyl ether. It has low gas permeability and performs very well in vacuum systems. Its resistance to ozone,...

1.7 Silicone Rubber (VMQ)

Silicone rubbers, also known as polysiloxanes, have a backbone of silicon–oxygen chains. They are designated by the letter Q, with the attached organic groups shown by their initials (methyl silicone MQ, phenyl methyl silicone PMQ, methyl vinyl silicone VMQ). They keep their properties over an extremely wide temperature range, resist high and low temperatures, and have a low dielectric constant. Their resistance to air, ozone, weathering and oil is very good. Their gas...