The "low temperature" structural behaviour of the binary system octadecane(C18H38) plus nonadecane (C19H40). Experimental equilibrium phase diagram

A new proposal of the equilibrium binary phase diagram implying the consecu tive n-alkanes octadecane (C18H38) and nonadecane (C19H40) is given. A more particular attention is focused on the structural behaviour at "low temper ature", i.e, in the domain of the solid ordered phases. X-ray powder diffra ction analyses performed at 273K have pointed out the presence of two ortho rhombic, one triclinic and one monoclinic monophasic domains at "low temper ature". The RI form is observed in a large domain of the composition range at higher temperature. No less than seven solid-solid and two solid-liquid domains have been characterised as well as two peritectoid, one eutectoid a nd one eutectic invariants.