Heat of dilution of polymer solutions. Part II. Atactic poly(methyl methacrylate) solutions

Abstract

A calorimetric method has been employed to measure the heat of dilution of atactic poly(methyl methacrylate), _v= 26,000, in both toluene and chloroform at 303·15 K. Further measurements in toluene with polymer of _v= 41,500 are also are reported. The apparent enthalpy parameter χ_H and the concentration-independent enthalpy parameter χ₁ have been calculated. For chloroform solutions χ_H is negative and for toluene solutions is positive over the range of average volume fractions examined. The results are discussed in relation to reported experimental data and the recent theories of polymer solutions.