1. POM manufacturing

In the 1950s, research into the manufacture of high-molar-weight polyformaldehyde was carried out in parallel by the DuPont and Celanese companies in two different ways.

• DuPont developed the polymerization of formaldehyde monomer using a tertiary amine initiator in a liquid hydrocarbon. The resulting polymer, which was relatively unstable, was stabilized by modifying the chain ends in an acetic anhydride solution. A patent was taken out in 1956, and DuPont publications described a thermally stable, high-molecular-weight polyoxymethylene (POM) defined as a linear acetal chain structure of unusually high crystallinity. Delrin was marketed in 1960.

• Celanese Corporation, for its part, has developed a solution based on the polymerization...