Tuning thermo-mechanical properties of poly(lactic acid) films through blending with bioderived poly(alkylene furanoate)s with different alkyl chain length for sustainable packaging

To favor a transition toward a more sustainable society, it is fundamental to find renewable and effective alternatives to current packaging materials. Here, fully renewable polymer films are produced by blending poly (lactic acid) (PLA) and poly (alkylene furanoate)s (PAFs). The work aims at discussing their microstructural and thermomechanical properties as a function of PAF concentration (5–30 wt%) and type (4–10 carbon atoms in the alkyl chain length of the repeating unit). For neat PAFs, an increase in the alkyl chain length promotes a decrease in Tg and Tm, but also an increasing tendency to crystallize, due to an enhanced molecular mobility. The Tg of PLA does not vary upon PAF addition, which accounts for blend immiscibility, in good agreement with SEM and FTIR. Tensile tests highlight that the addition of 5 wt% of any of the considered PAFs leads to a strong enhancement of the strain at break, which increases of approx. 10 times in the blend containing 5 wt% of poly (decylene furanoate) (PDeF-5). This remarkable increase in ductility is investigated more in detail with the essential work of fracture (EWF) approach, which evidences that the specific essential work of fracture increases from 16.2 kJ/m2 of neat PLA up to 32.9 kJ/m2 of PDeF-5 (+103%). This occurs especially thanks to the remarkable increase in essential work of fracture propagation (+222%). This work highlights the beneficial effect of finely dispersed PDeF domains on the fracture resistance of PLA, which is a fundamental aspect for many industrial applications.