Thermosets have been on my mind lately.

Thermosets have been on my mind lately. I have been perusing 1955 issues of Plastics Technology for our 50th anniversary columns. Back then, thermosets were close to half the 2.6 billion lb of plastics resins used in the U.S. The only plastics whose production and sales volumes were large enough for the U.S. government to count individually were urea, melamine, phenolic, unsaturated polyester, PVC, polystyrene, and polyethylene. In those days, if you wanted a plastic for really tough jobs, you chose a thermoset.

Today, thermosets account for less than 11% of the 91 billion lb of plastics processed in North America. They are still among the most heat- and abuse-resistant plastics around, and among the most economical. But longer cycle times, greater difficulty recycling, higher labor costs, and environmental considerations have eroded their appeal relative to thermoplastics.

Thermosets' shrinking role has mirrored the contracting roster of thermoset materials suppliers. In the past month, eight of those suppliers suddenly became three. In one gulp, Borden Chemical absorbed Bakelite AG of Germany along with Resolution Performance Products (formerly Shell's epoxy business) and Resolution Specialty Materials (formerly part of Eastman Chemical and before that, McWhorter Technologies). Simultaneously, Sumitomo Bakelite of Japan (which had earlier acquired Durez, the biggest U.S. name in phenolics) gobbled up Vyncolit of Belgium, which not so long ago bought Rogers Corp. Then Bulk Molding Compounds Inc. took over Rodgers Engineering.

Don't cry for thermosets. They still account for almost 10 billion lb/yr of U.S. plastics, and they had healthy growth of around 5% last year. Thermosetting composites still have new fields to conquer in aerospace, automotive, and infrastructure. They'll probably be going strong when this magazine celebrates 100 years.