Nylon 66 fundamentals and its processes

The objective of this paper is to search for and critically examine the pertinent details of the current bulk continuous nylon 66 processes (described in the patents), which are practiced or followed by most nylon producing industries. The two monomers for making nylon 66 and their homologues including dibasic and monobasic acids, diamines, and primary amines show very interesting melting point behavior. On the other hand, compounds containing even numbers of carbon atoms show consistently higher melting points than the neighboring odd number compounds of higher molecular weights. However, the boiling points of all four series follow the usual rule: The higher the molecular weight, the higher the boiling point. It has been proven that the quality of nylon 66 has been greatly improved by lowering the residence time during the polymerization. For instance, the spinning rate employed was at a level of 7000 m/min, and the tensile strength of the spun yarn was much improved, which was attributed to the overall quality of the polymer.