AbstractBecause PVC mixes very slowly with plasticizer, analogs of PVC were used to obtain heats of mixing via direct calorimetry. Initial studies were done with DBP, DOP, and DOS plasticizers and chloroform, 1,3‐dichloropropane, and 2,4‐dichloropentane as the analogs. Simultaneous calculations for the enthalpy of mixing were done using the UNIFAC‐FV model. Both the propane and the pentane derivatives behaved according to the predictions of UNIFAC. Both experiments and calculations suggested that 1,3‐dichloropropane is a better model for PVC than 2,4‐dichlo