Full definition
Elastomers are a class of polymers characterized by their ability to undergo significant deformation and return to their original shape upon the removal of stress. This unique property differentiates them from more rigid plastics, making elastomers essential in various industrial applications. The elastic behavior of elastomers is primarily due to their long, flexible polymer chains that are interconnected through chemical cross-links, a process known as vulcanization. This cross-linking forms a three-dimensional network that allows the material to stretch and recover, providing the necessary resilience for many applications.
The primary families of elastomers include natural rubber (NR), styrene-butadiene rubber (SBR), neoprene (CR), nitrile rubber (NBR), ethylene propylene diene monomer (EPDM), silicone (VMQ), polyurethane (PU), fluoroelastomers (FKM), and butyl rubber (IIR). Each of these elastomers has distinct properties and applications based on their chemical composition and structure. For example, NBR is known for its excellent oil resistance, making it suitable for seals and gaskets in automotive applications. In contrast, EPDM is favored for outdoor applications due to its superior weather and ozone resistance.
Elastomers are classified according to ASTM D2000 and SAE J200 standards, which utilize a two-letter designation system to indicate their properties. The first letter signifies heat resistance, ranging from A (70°C) to J (275°C), while the second letter denotes oil resistance, from A (no requirement) to K (highest oil resistance). Essential properties specified include hardness measured in Shore A, tensile strength in megapascals (MPa), elongation percentage, compression set percentage, specific gravity, and applicable temperature ranges. The global elastomer market is substantial, with a production volume of approximately 30 million tonnes per year, where natural rubber and SBR account for over 60% of this volume, reflecting their widespread use in various sectors such as automotive, construction, and consumer goods.