The rheological properties of PLA and PCL matrices and their composites were measured in a HAAKE MARS 40 rheometer (Thermo Fisher Scientific, Inc.) equipped with electrical temperature modules (TM-EL-P and TM-EL-H) and parallel plates of 20 mm diameter. The test specimens were cut from injection moulded sheets. All samples were measured in oscillation mode at a temperature of 180 °C and 120 °C for PLA-based and PCL-based materials, respectively. First, the amplitude sweep test was performed at a frequency of 1 Hz to determine the linear viscosity range (LVR) of all samples. Then the oscillation frequency sweep frequency tests were performed at 0.1% strain.