Plasticization of poly(lactic acid) through blending with oligomers of lactic acid: Effect of the physical aging on properties

Two oligomers of lactic acid (OLAs), carboxyl (OLA-COOH) or hydroxyl (OLA-OH) end
capped, were employed to modulate physical and mechanical properties of poly(lactic
acid), PLA. Blends up to 25 wt.% by weight of OLAs were prepared by melt mixing.
Mechanical, thermal and transport properties of the materials were tested as a function
of OLA functional moieties and blend composition. Moreover, the effect of physical aging
on structure and properties of blends was studied by storing the samples in controlled temperature
and humidity conditions, up to 8 weeks.
OLAs significantly affect mechanical properties of PLA; blends showed an interesting
ductility even after aging, suggesting their use as flexible films. Moreover, gas transport
and total migration properties of blends are suitable for packaging applications.