The PLA/lignin composites were mechanically tested by MTS
Insight 10 equipment provided with pneumatic clamps (Advantage
Pneumatic Grips) and with a loading cell of 250N with a speed
of 5 mm/min. The stress/strain measurements were performed
using a video extensometer with digital video camera attached
to a PC. The starting distance between the clamps was 25mm.
Samples with 6 cm long were prepared, with thicknesses between
0.76–0.43mm, and width of 3.4–1.3mm. The values quoted are the
average of nine measurements.