The transport theory for the solids conveying zone in a single-screw extruder was applied to calculate the pressure distributions along the screw channel for several bisphenol A polycarbonate resins based on the screw revolution speed and the flow rate. The pressure distributions and the flow rates of the resins were related to the structural and rheological properties. When polymers have die same chemical structure and number-average molecular weight and the same mechanical properties, the polymer having a broader molecular weight distribution showed a lower glass transition temperature. For the polymer with broader MWD a relatively low pressure was developed along the screw channel, and an increased flow rate was observed. A relatively short melting length was also observed for this polymer and, accordingly, it was concluded that the polymer with a broader MWD has a better processability.