The number-average (Mn), weight-average molecular weights (Mw) and molecular weight distributions (MMD) were to be determined using calibrated gel permeation chromatography (GPC) in chloroform (TCM) against polystyrene standards. The flow rate was set to 1 mL/min and the measuring temperature was defined as 25 °C. For this characterization method, granulated samples were used with a concentration of 5 mg/mL and a injection volume of 100 μL.

Approx. 20 mg of each of the unfilled PLA samples and 40 mg of each of the starch-filled samples were weighed into 4 mL sample vials and mixed with 4 mL of chloroform. This corresponds to a sample concentration of approx. 5 mg/mL in relation to the PLA content. The solutions were tempered for 1 h at 60 °C to improve solubility and dissolved for 16 hours at room temperature with gentle shaking. The samples were then filtered through 1 μm PTFE syringe filters, filled into 1.5 mL sample vials and injected into the GPC. Two solutions of each sample were prepared.