Published April 2014
This report provides a world overview of elastomer supply and demand; however, the various CEH reports on each of the individual elastomers are the definitive source of data and information for each elastomer. This report covers the following large-volume synthetic elastomers (as well as natural rubber), which are referred to as general-purpose elastomers: butyl, ethylene-propylene, nitrile, polybutadiene, polychloroprene (neoprene), polyisoprene and styrene-butadiene (SBR).
The following pie charts show world consumption of natural rubber and synthetic elastomers.
Although the report does not cover specialty elastomers in detail, they are included in total elastomer production and consumption for individual countries, regions and world totals. Specialty elastomers meet an ever-growing demand for high-tech components for use in difficult environments that require resistance to heat, low temperature, high pressure, oxygen, ozone, weathering, oil, solvents and chemicals. These specialty elastomers include polyacrylic, chlorinated polyethylene, chlorosulfonated polyethylene, epichlorohydrin, fluoro and silicone elastomers, polynorbornene, polysulfide, propylene oxide, transpoly-octenamer and vinyl acetate–ethylene elastomers. Although not typically thought of as specialty elastomers, polyurethane elastomers (excluding flexible and rigid foams) are included in this group for organizational purposes.
In contrast to the general-purpose elastomers, specialty elastomers offer one or more definite outstanding performance attributes, such as heat resistance, low-temperature flexibility, weatherability or chemical resistance. Specialty elastomers are generally relatively high in price and are used only in applications where their specific outstanding performance features are necessary to meet technically demanding design conditions; consequently, the volumes consumed are relatively small. A wide variety of specialty elastomers are available, offering the design engineer an opportunity to select a material with optimum performance and cost for the specific application. This selection, however, is not always easy because of the proliferation of materials available, many of which overlap each other in cost and/or performance.
Major applications for specialty elastomers are in automotive components and parts, wire and cable insulation and jacketing, aerospace equipment, industrial belts, hoses and tubing and other applications where high-temperature resistance, oil resistance, and weatherability are required; sealants and caulks; pond and pit liners and roofing membranes; medical equipment and implants; components and pollution control systems; and a host of miscellaneous uses.
General-purpose and specialty elastomers constitute the thermoset elastomer family. Thermoset elastomers require heat for cross-linking the parts (or vulcanization if sulfur is used as the cross-linking agent) after extrusion or molding processes to fully develop their elastic properties. Cross-linking normally requires 150–180°C and 3–30 minutes, depending on the thickness of the parts. After cross-linking, thermoset elastomers develop unparalleled properties such as high resilience, low compression set, excellent abrasion resistance, good solvent resistance and deformation resistance at high temperature. Thus, thermosets still dominate the most critical applications such as tires, high-voltage cables and seals. However, longer cycle times and high energy requirements greatly increase the processing costs of thermoset elastomers. Moreover, the feedstock to an extruder or molding machine has to be in strip or sheet form, which is more cumbersome to handle. After cross-linking, the scraps of thermosets cannot be recycled.
Thermoplastic elastomers (TPEs) were developed to overcome the above-mentioned disadvantages of thermosets. TPEs can be processed like most plastics. They can be fed to the extruders or molding machines in pellets, do not require heat cross-linking and the scraps can be recycled. Although they do not possess the same critical properties as thermosets, TPEs have adequate softness and resilience for less critical applications such as adhesives, footwear, low-voltage wire and cable insulation, and polymer modification. Because of the fast cycle time, recyclability and overall cost-effectiveness, TPEs have become the fastest-growing of all major elastomer groups, growing at a much faster rate than traditional elastomers—generally 5–7% per year on a global basis in recent years. However, detailed discussion of thermoplastic elastomers (TPEs) is outside the scope of this overview.