In order to further investigate the T g,β and T g,α values measured by THz-TDS using a well-established reference method samples of low, medium and high MW PLGA 75:25 as well as medium and high MW PLGA 50:50 were studied using DMA. DMA measurements were performed using the dynamic-mechanical analyser Q800 DMA from TA Instruments (New Castle, De, USA). The oscillation amplitude was set to 20 µm and the test frequency was held constant at 1 Hz. The DMA measurements were carried out during heating with a temperature sweep covering the range of 138 -358 K. The initial stabilisation time at 138 K was set to 5 minutes, and the heating rate was 3 K min -1 with measurements continuously acquired throughout heating of the sample. Two experimental repeats were completed for each material, with a fresh sample prepared before each experimental run.