HEATS OF DILUTION OF POLYISOBUTYLENE SOLUTIONS

Abstract

The measurements of heats of dilution of polyisobutylene solutions in benzene, toluene, and chlorobenzene have been carried out with a Tian–Calvet microcalorimeter at 25 °C. The dilution technique previously described has been improved and the extrapolated enthalpy parameter κ₁* for each system has been corrected for the excluded volume effect using the Krigbaum–Carpenter–Kaneko–Roig formulation for the second virial coefficient A₂. No detectable variation in κ₁* was found for high molecular weights (≥ 43,000); but a definite increase in κ₁* was found for very low molecular weights.