Era of elastomers

Imagine a material that combines the toughness and loadbearing capacity of metal, the abrasion resistance of ceramics and the resilience of rubber. Add several processing and performance options for economy and efficiency and you've got polyurethane elastomers, extremely versatile materials which can be subdivided into five groups:

• Millable gums, which can be processed on standardrubber processing equipment;

• Cast elastomers, both solid and microcellular cast systems, both heat- and room-temperature curable;

• Fibers of the type known widely as Spandex, usually produced by solution dry spinning of polyurethane polymers;

• Thermoplastic urethanes or TPU's, solid polymers injection moldable on conventional plastic processing equipment, and;

• RIM and RRIM elastomers, low density microcellular elastomers processed on reaction injection molding equipment.

The history of polyurethane elastomers began more then 150 years ago and continues today as new application ideas spur growth and diversification, while ongoing technical development works to make those ideas commercial realities.

The first 90 years of this history could aptly be called the Era of Discovery. It began in 1849, when Wurtz first isolated an isocyanate molecule, and takes us through 1937, when Otto Bayer first discovered the diisocyanate polymerization reaction. One goal of this early research was to duplicate or surpass the properties of nylon.

Through the 40s, 50s and 60s, a few key urethane producers built upon this fundamental understanding of the urethane reaction to develop process technology, products and markets for elastomers. This stage can appropriately be called the Era of Development Highlights included:

• Introduction of Adiprene B isocyanate cured millable gums by Du Pont in 1954;

• Introduction of Adiprene castable systems by Du Pont as a rubber replacement in 1958, and;

• Introduction of Spandex under the name "Fiber K" by Du Pont in 1958.

By the late 60s polyurethane elastomers were entering a period of accelerated growth and development.

This, then, is the Era of Response, when a fast-changing world created new market niches for elastomers. At the beginning of this era, in 1970, U.S. consumption of non-cellular polyurethane was about 56 million pounds in four major categories - millable gums, liquid castables, thermoplastic elastomers and fibers.

Now automotive applications may represent the major end use by volume. But they by no means reflect the broad application diversity of elastomers, which by now have found their way into uses from helicopter covers to artificial hearts, from cattle tags to running tracks.

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