Thermodynamic and diffraction analyses were performed to establish the phase diagram for a binary system between 4-n-nonyl-4'-isothiocyanatobiphenyl (9TCB) and n-nonane. The swollen SmE structure is identified in the binary system. Upon swelling : a characteristic two-dimensional herringbone array is Maintained whereas the layer spacing of SmE structure increases with the content of n-nonane. Considering the difficulties in explaining the experimental findings based on the traditional model of SmE structure,, a new model lamellar with two types of sublayers consisting of aromatic core and chain moieties, is proposed.