alfa-costic acid, a plant sesquiterpenoid from Dittrichia viscosa, as modifier of Poly (lactic acid) properties: a novel exploitation of the autochthone biomass metabolite for a wholly biodegradable system

In this work, ??costic acid (?-CA), a metabolite coming from a perennial autochthon shrub
Dittrichia viscose, was used as natural additive of polylactic acid (PLA), a biodegradable
thermoplastic polymer, in order to modulate its chemico-physical properties, for the achievement
of a wholly biobased packaging system. It's the first time that ??costic acid is exploited for this
appealing and novel application. The investigations performed on PLA/?-CA films, evidenced
strong physical interaction occurring between the polymer and ?-CA, as confirmed by NMR and
FTIR-ATR analyses; SEM micrographs showed a good embedding of ?-CA particles inside PLA
polymer matrix; GPC analysis highlighted a slight hydrolysis of polymer matrix clearly
evidenced in mechanical properties. DSC analysis underlined the significant decreasing of Tg,
associated with the increase of PLA chain mobility. TGA thermograms evidenced one broad
degradation profile of PLA/?-CA system, accounting for the weighty physical interaction
occurring between the polar groups of both polymer and plasticizer. Finally, PLA surface
wettability notably enhanced by the inclusion of ?-CA polar groups. In conclusion, ?-CA can be
considered as a promising plasticizer of PLA and a worthy modifier of its overall properties.