Wesley Memeger Jr.
Wesley Memeger, Jr. solved a major problem in the Kevlar process that allowed the timely start-up of the first Kevlar plant. In the laboratory, the polymer for Kevlar was prepared by polymerizing para-phenylene diamine and terephthaloyl chloride in a mixture of two solvents abbreviated HMPA (hexamethylphosphoramide) and NMP (N-methylpyrrolidinone). In the course of his research, he discovered that contrary to prior opinion, a polymer with satisfactory molecular weight could be made using only HMPA. This result translated to the commercial process involving a continuous polymerizer unlike with the two solvent system, which gave polymer of insufficient molecular weight for the preparation of Kevlar with satisfactory properties. Thus, Memeger's suggestion allowed for DuPont to meet its commitment to building a commercial scale plant, which would have been impossible with the two solvent system.
In the early 1970s, HMPA was used to make Kevlar, but some toxicology tests at the company’s Haskell Laboratory raised doubts about the safety of the solvent. DuPont then replaced HMPA with NMP and calcium chloride. Memeger spent most of his subsequent career at DuPont investigating: 1. other materials with properties similar to those of Kevlar. These were melt processible polymers, which did not have chemical and thermal stability equal to Kevlar; and 2. ring opening routes to polymers with novel properties. An accomplished artist, Memeger continues to be impressed by the elegance and simplicity of the Kevlar polymer that produces such remarkable properties.