Bio-based composites made of poly(L-lactic acid) (PLLA) and β-cyclodextrin/d-limonene inclusion complex (CD-Lim) were prepared by melt extrusion. Encapsulation of volatile d-limonene molecules within β-cyclodextrin cages was proven to be a successful strategy to prevent evaporation during high-temperature processing. However, small amounts of limonene were released upon processing, resulting in the plasticization of the polymeric matrix. Morphological analysis revealed good dispersion of the filler, which acted as a nucleating agent, favoring the growth of PLLA crystals. The composites′ lowered glass transition temperature upon the addition of CD-Lim was also proved by thermomechanical analysis (DMA). Moreover, DMA revealed constant stiffness of modified materials at room temperature, which is crucial in PLLA-based formulations.

Composites made of poly(L-lactic acid) (PLLA) and β-cyclodextrin/D-limonene inclusion complex (CD-Lim) are prepared to develop novel food packaging material with antibacterial properties. The composites are formulated with bio-based materials that are also biodegradable. The addition of CD-Lim to PLLA results in enhanced permeability and water uptake. Optical properties of PLLA/CD-Lim composites also significantly vary compared to plain PLLA, with partial loss of transparency and gloss, but sizably increased barrier to UV light, which imparts protection from oxidation to lipid-containing food. The mechanical properties of the composite films are also affected by composition. Most notably, PLLA films containing CD-Lim display significant antibacterial and antifungal properties, proving their potential as active food packaging films.

Bio-based composites made of poly(l-lactic acid) (PLLA) and pine wood were prepared by melt extrusion. The composites were compatibilized by impregnation of wood with γ-aminopropyltriethoxysilane (APE). Comparison with non-compatibilized formulation revealed that APE is an efficient compatibilizer for PLLA/wood composites. Pine wood particles dispersed within PLLA act as nucleating agents able to start the growth of PLLA crystals, resulting in a faster crystallization rate and increased crystal fraction. Moreover, the composites have a slightly lower thermal stability compared to PLLA, proportional to filler content, due to the lower thermal stability of wood. Molecular dynamics was investigated using the solid-state 1H NMR technique, which revealed restrictions in the mobility of polymer chains upon the addition of wood, as well as enhanced interfacial adhesion between the filler and matrix in the composites compatibilized with APE. The enhanced interfacial adhesion in silane-treated composites was also proved by scanning electron microscopy and resulted in slightly improved deformability and impact resistance of the composites.

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Composites made of linear low-density polyethylene (LLDPE) and β-cyclodextrin/<font style="font-variant: small-caps">d</font>-limonene inclusion complex (CD-lim) were prepared by melt extrusion to develop a novel food packaging material. Scanning electron microscopy evidenced a fairly good dispersion of the filler within the polymeric matrix. Infrared spectroscopy coupled with thermogravimetric analysis confirmed the presence of CD-lim in the composites, proving that the applied technology of including the essential oil within β-CD cages allows for preventing a sizable loss of <font style="font-variant: small-caps">d</font>-limonene despite a high temperature and shear applied upon extrusion processing. Moreover, the influence of the filler on the thermal properties of PE was assessed. It was found that the cyclodextrin-based inclusion complex significantly fastens the crystallization path of the polyethylene matrix with an improved crystallization rate of the PE/CD-lim composites compared to the neat polymer.

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Polyolefins such as polypropylene are used in an immensely broad range of commodity products and account for the largest volume of synthetic polymers generated worldwide. For this reason, this family of thermoplastics contributes significantly to solid waste both on land and in the ocean. One viable approach to mitigate this growing problem and simultaneously reduce the cost of and dependence on petroleum-based polymers relies on blends wherein an added biopolymer can promote natural biodegradation. Due to their chemical dissimilarity, however, nonpolar polyolefins and polar biopolymers tend to phase-separate, in which case a fundamental, molecular-level understanding of the role of polymer/polymer interfaces on chain mobility in blends differing in composition is needed. In the present study, the molecular dynamics of blends composed of isotactic polypropylene (iPP) and glycerol-plasticized thermoplastic starch (TPS) are investigated by solid-state proton nuclear magnetic resonance and dielectric relaxation spectroscopies. Blends prepared by twin-screw extrusion range in composition from 10 to 70 wt % TPS, and their morphologies and thermal properties are examined by scanning electron microscopy and differential scanning calorimetry, respectively. This comparative analysis establishes the influence of TPS on the molecular dynamics of biphasic iPP/TPS blends relative to the constituent homopolymers.

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