Reaction kinetics and simulation for the solid-state polycondensation of nylon 6

A comprehensive model for the solid-state polymerization (SSP) of nylon 6 h as been developed. With regard to the reactive end-to-end distance distribu tion, for the well-stirred system in which there is a homogeneous distribut ion, the whole process of SSP has been divided into two stages in this mode l. The polymer crystalline fraction is modeled as containing only repeat un its, thus concentrating end groups, condensate and monomers in the amorphou s fraction. Many effects neglected by previous models are considered, such as variable crystallinity, the effect of leaching and end-to-end distance d istribution. A more practical technique has been used to generate the initi al values used for simulation, which were then used to obtain the optimal p arameter values. Detailed quantitative results were obtained to study the e ffects of changing the important operating conditions on SSP, such as inter mediate remelting of nylon 6 pellets and leaching of monomer and water befo re SSP.