Poly(butylene succinate)-based composites containing β-cyclodextrin/d-limonene inclusion complex

• Inclusion complex (IC) of d-limonene inside β-cyclodextrins (β-CD) cages was prepared.
• Poly(butylene succinate) (PBS) and IC composites were prepared by melt extrusion.
• Homogeneous dispersion of IC in PBS was proven by optical microscopy and infrared spectroscopy.
• d-limonene was thermally stabilized upon inclusion within β-CD cages as shown by TGA analysis.
• IC delays melt crystallization of PBS as shown by isothermal and non-isothermal DSC analysis.

Structural, morphological and thermal properties of films based on poly(butylene succinate) (PBS) and inclusion complex (IC) of β-cyclodextrins (β-CD) and d-limonene were studied, in order to prepare novel bio-active food packaging materials. Formation of the inclusion complex was proved by infrared spectroscopy, nuclear magnetic resonance, and X-ray diffraction. The IC contains 7 wt% of d-limonene, as quantified by precipitation, as well as by 13C NMR and by thermogravimetry. Inclusion within β-CD cavity stabilizes d-limonene against evaporation, which allows melt compounding with PBS. Infrared spectroscopy of compression molded composite films, evidenced both the d-limonene encapsulation inside β-CD cages, and the occurrence of interactions between hydroxyl groups of β-CD-lim complex and the carbonyl groups of PBS units. Optical micrographs showed a phase separated morphology, with homogeneous distribution of the IC within the PBS matrix, probably due to interactions between the polar groups of the composite components. DSC analysis highlighted the anti-nucleating action of β-CD-lim complex towards PBS, evidenced by a significant delay in crystallization kinetics of PBS.

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