Natural
terpenes such as linalool (L), geraniol (G), and geranyl
acetate (GA), from 10 to 20 wt %, were compounded with poly(3-hydroxybutyrate)
(PHB) to assess the influence of the content of these biobased molecules
on the structural and mechanical properties of PHB. Differential scanning
calorimetry (DSC) measurements showed a decrease of T
g from 8.5 °C to −13 °C, showing the
plasticization effect of the terpenes. This effect is correlated with
the decrease of the crystallinity degree from 57 to 36%. Moreover,
tensile tests were conducted on PHB-containing terpenic plasticizers.
The increase of the elongation at the break of the plasticized PHB
over 650% combined with a decrease of the Young’s modulus with
regard to pure PHB were obtained in the presence of 20 wt % of geranyl
acetate. Dynamical mechanical analysis also revealed that the use
of terpenes as additives promoted the decrease of E′ and the
glass transition temperature. The effect is more pronounced with geranyl
acetate due to the presence of the segment bearing an ester group
that increases free volume and molecular mobility. Among the different
plasticizers used here, the addition of geranyl acetate is an attractive
way to obtain soft PHB from renewable additives.
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