Effects of sorption modes on the transport and physical properties of nylon 6

The presence of low molecular weight molecules in a polymeric matrix often has a marked effect on material properties. Knowledge of specific penetrant distributions and component interactions is important for an elucidation of structure‐property relationships, plasticization phenomena, and any modification of structure induced by the presence of penetrants. The sorption‐mode characteristics of water, methanol, and ethanol in Nylon 6 films have been investigated by the application of the differential sorption method. The sorption and diffusion behavior were interpreted in terms of clustering theory with suitable account being made for penetrant molecular size and hydrogen‐bonding capability. The examination of transport and mechanical properties of these films indicates a pronounced dependence of those properties on the concentration of penetrants. The effect of penetrant cluster formation at characteristic concentrations of sorbed penetrant is to decrease the concentration dependence of both diffusion and mechanical relaxation processes in the case of alcohols. The onset of water clustering apparently only affects the mechanical relaxation process. The samples were further characterized by DSC, X‐ray diffraction and density measurements to detect any significant changes in the structure of Nylon 6 induced by the penetrant conditioning.