1. See for example, S.L. Kwolek, (DuPont), U.S. Patent 3,600, 350 (1971).
2. S.G. Cottis, J. Economy and B.E. Nowak (Carborundum), U.S. Patent 3,637, 595 (1972).
3. S.G. Cottis, J. Economy and L.C. Wohrer (Carborundum), U.S. Patent 3,975, 487 (1976).
4. F.E. McFarlane, lecture, Gordon Research Conference on Polymers (1974);
5. H.F. Kuhfuss and W.J. Jackson, Jr. (Eastman Kodak), U.S. Patent 3, 778, 410 (1973).