The Zone Melting and Solid-Liquid Equilibrium of the 2, 2'-Bipyridyl- Biphenyl Eutectic Systemt

Abstract

Solid solubilities in the 2, 2'-bipyridyl biphenyl eutectic system at the eutectic temperature, which correspond to the maximum solubilities, were determined by means of DSC, zone melting and thermal microscopic methods. In this system the relationship between eutectic enthalpy of fusion determined by DSC and composition led to the following straight lines:
ΔH₁^e=35.53x₂-2.037
ΔH₂^e=32.17x₂+ 31.302
where x₂ is the mole fraction of 2, 2'-bipyridyl;
ΔH₁^e and
ΔH₂^e are the eutectic enthalpies of fusion on the 2, 2'-bipyridyl and biphenyl sides from the eutectic composition, respectively. Putting
ΔH₁^e=0 and
ΔH₂^e= 0 in the above equations, the maximum solid solubilities were found to be x₁^es= 0.0270 and x₂^es= 0.0573 by mole fraction for the 2, 2'-bipyridyl and biphenyl sides, respectively. Moreover, eutect ic composition was found to be x₁^e= 0.493 by putting ΔH₁^e=ΔH₂^e. On the other hand, solidus curve in the biphenyl side was determined from the equilibrium distribution coefficient of 2, 2'-bipyridyl in biphenyl derived from zone melting experiment, and also the value of x₂^es was found to be 0.0705. By the use of a thermal microscope the solid solubilities were found to be x₁^es= 0.0192 and x₂^es=0.0603, respectively. I Studies of the Zone Melting. Part 9.