EFFECT OF BRANCHED-CHAIN POLYMERS ON BOND EQUILIBRIUM IN LIQUID SE-TE ALLOYS

The statistical-mechanical method for deriving the usual expression for the law of mass action (LMA) is modified by replacing the configuration entropy Sc of an ideal solution with an expression which reflects the polymeric structure. A quasilattice model is used to determine Sc, using an extension of a method due to Flory. The present work ignores the effects of ring molecules, which may play an important role in real alloys. The derived expressions for the concentrations of neutral or electrically charged dangling bond (1F) and threefold bonded (3F) atoms are modified from the LMA results by factors whose values depend on the total concentrations of 1F and 3F atoms. They reflect the entropies of formations s1 and s3 of 1F and 3F constituents which are functions of the average number ≫ of chain branches per molecule. When ≫ is large s1-s3k ln≫. The effects of alloying are essentially independent of the polymer effect, and are the same as what is predicted by LMA. © 1979 The American Physical Society.