Phase behavior of dodecane–tridecane mixtures confined in SBA-15

Phase behavior of dodecane–tridecane ( n -C 12 H 26 –C 13 H 28 , C 12 –C 13 ) mixtures in bulk and confined in SBA-15 have been investigated using differential scanning calorimetry. Bulk C 12 –C 13 system has a complicated behavior due to special rotator phase. It has been found that phase diagram of C 12 –C 13 /SBA-15 (3.8 nm) system is a straight line, C 12 –C 13 /SBA-15 (7.8 nm) a curve, and C 12 –C 13 /SBA-15 (8.9, and 17.2 nm) a loop line. The growth of the phase diagram shows size effect on phase behavior of C 12 –C 13 mixtures. Moreover, in the range of 3.8–17.2 nm melting temperatures of pure C 12 and mixtures at mole fractions x C13  = 0.1–0.5 have linear relation with inverse pore diameter, while C 13 and mixtures at x C13  = 0.6–0.9 present curved lines. The confined mixtures show a similar melting behavior with pure C 12 , C 13 .