Rigid poly(vinyl chloride) (PVC) compounds were prepared in a Haake torque rheometer using various blending conditions. The fusion levels of processed compounds were evaluated by a capillary rheometer and differential scanning calorimetry (DSC), based on the entrance pressure drop and the heat of fusion, respectively. S-shaped fusion curves were obtained. Starting temperature of the mixer, rotor speed, and totalized torque are the three major factors that affect the fusion level of PVC compounds blended in the Haake torque rheometer. All three parameters have a significant effect; however, totalized torque has the greatest effect and this can be characterized using a torque rheometer. Both capillary rheological and DSC thermal analysis can be applied to determine the fusion level of a PVC compound. The morphological changes of the various fusion processes were characterized by scanning electron microscopy (SEM).