The present work proved that poly(lactic acid) can be effectively
plasticized with oligomeric lactic acid, being miscible at
least up to 25 wt% concentration. The significant decrease in
glass transition temperatures observed with increasing OLA
concentration was well correlated with the increase in the blends
ductility. No phase separation was detected for concentrations up
to 25 wt%, confirming the high compatibility of OLA with PLA.
The ageing study showed that depending on the plasticizer
content, the evolution of tensile properties over time could be
affected by the physical ageing related to an enthalpy relaxation
process (as in PLAe15 wt% OLA) and the progressive densification
of the matrix due to an increased chain mobility for materials
showing Tg values near or below the storage temperature (as
in 25 wt% OLA formulation). Besides, it is important to remark
that the same formulation could show either a brittle or ductile
behaviour depending on the temperature at which the material
is stored and used.