Dataset Information

Uniformly Dispersed Poly(lactic acid)-Grafted Lignin Nanoparticles Enhance Antioxidant Activity and UV-Barrier Properties of Poly(lactic acid) Packaging Films.

ABSTRACT: Poly(lactic acid) (PLA) represents one of the most widely used biodegradable polymers for food packaging applications. While this material provides many advantages, it is characterized by limited antioxidant and UV-barrier properties. Blending PLA with lignin is an attractive strategy to address these limitations. Lignin possesses antioxidant properties and absorbs UV-light and is a widely available low value byproduct of the paper and pulp industry. This study has explored the use of lignin nanoparticles to augment the properties of PLA-based films. A central challenge in the preparation of PLA-lignin nanoparticle blend films is to avoid nanoparticle aggregation, which could compromise optical properties as well as antioxidant activity, among others. To avoid nanoparticle aggregation in the PLA matrix, PLA-grafted lignin nanoparticles were prepared via organocatalyzed lactide ring-opening polymerization. In contrast to lignin and unmodified lignin nanoparticles, these PLA-grafted lignin nanoparticles could be uniformly dispersed in PLA for lignin contents up to 10 wt %. The addition of as little as the equivalent of 1 wt % of lignin of these nanoparticles effectively blocked transmission of 280 nm UV-light. At the same time, these blend films retained reasonable visible light transmittance. The optical properties of the PLA lignin blend films also benefited from the well-dispersed nature of the PLA-grafted nanoparticles, as evidenced by significantly higher visible light transmittance of blends of PLA and PLA-grafted nanoparticles, as compared to blends prepared from PLA with lignin or unmodified lignin nanoparticles. Finally, blending PLA with PLA-grafted lignin nanoparticles greatly augments the antioxidant activity of these films.

SUBMITTER: Boarino A

PROVIDER: S-EPMC9274615 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature

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Uniformly Dispersed Poly(lactic acid)-Grafted Lignin Nanoparticles Enhance Antioxidant Activity and UV-Barrier Properties of Poly(lactic acid) Packaging Films.

Boarino Alice A Schreier Aigoul A Leterrier Yves Y Klok Harm-Anton HA

ACS applied polymer materials 20220524 7

Poly(lactic acid) (PLA) represents one of the most widely used biodegradable polymers for food packaging applications. While this material provides many advantages, it is characterized by limited antioxidant and UV-barrier properties. Blending PLA with lignin is an attractive strategy to address these limitations. Lignin possesses antioxidant properties and absorbs UV-light and is a widely available low value byproduct of the paper and pulp industry. This study has explored the use of lignin nan ...[more]

PMID: 35846781

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Project description:Lignin, being one of the main structural components of lignocellulosic biomass, is considered the most abundant natural source of phenolics and aromatics. Efforts for its valorisation were recently explored as it is mostly treated as waste from heat/energy production via combustion. Among them, polymer-based lignin composites are a promising approach to both valorise lignin and to fine tune the properties of polymers. In this work, organosolv lignin, from beech wood, was used as fillers in a poly (lactic acid) (PLA) matrix. The PLA/lignin composites were prepared using melt mixing of masterbatches with neat PLA in three different lignin contents: 0.5, 1.0 and 2.5 wt%. Lignin was used as-isolated, via the organosolv biomass pretreatment/fractionation process and after 8 h of ball milling. The composites were characterised with Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy, X-ray Diffraction (XRD), and Differential Scanning Calorimetry (DSC). Additionally, their antioxidant activity was assessed with the 2,2-Diphenyil-1-picrylhydrazyl (DPPH) method, the colour was measured with a colorimeter and the mechanical properties were evaluated with tensile testing. Ball milling, at least under the conditions applied in this study, did not induce a further substantial decrease in the already relatively small organosolv lignin primary particles of ~1 μm. All the produced PLA/lignin composites had a uniform dispersion of lignin. Compression-moulded films were successfully prepared, and they were coloured brown, with ball-milled lignin, giving a slightly lighter colour in comparison with the as-received lignin. Hydrogen bonding was detected between the components of the composites, and crystallization of the PLA was suppressed by both lignin, with the suppression being less pronounced by the ball-milled lignin. All composites showed a significantly improved antioxidant activity, and their mechanical properties were maintained for filler content 1 wt%.

Project description:Microbial contamination and the need for sustainable food production are driving the shift toward biodegradable food packaging materials. There is an urgent need to develop smart food packaging materials that can prevent contamination and prolong the shelf life of meat. To achieve this, the physical-chemical characteristics of polyvinyl alcohol (PVA)-based packaging films were enhanced through incorporation of lactic acid and anthocyanins to act as a pH indicator. The mechanical, hydrophilic, barrier, and antibacterial properties of the composite films were then evaluated to test the ability of the film to act as a packaging material. In addition, the surface morphology was studied by scanning electron microscopy (SEM), the functional groups by Fourier transform infrared (FTIR) spectroscopy, optical transparency using ultraviolet-visible (UV-vis) spectrophotometer, crystallinity by powder diffraction, and their thermal properties by thermal gravimetric analysis (TGA). The films had a swelling degree (SD) of 222.60 ± 21.19%, dry content (DC) of 70.56 ± 2.54%, moisture content (MC) of 29.44 ± 2%, ALRO moisture (AM) content of 41.85 ± 5.06, and total soluble matter (TSM) of 8.05 ± 1.05%. Moreover, incorporation of lactic acid enhanced the mechanical and the thermal properties of the films but it reduced their optical transparency. The water vapor permeability (WVP) was found to be 14.32 × 10-3 g-1 s-1 Pa-1 and it inhibited the growth of Escherichia coli (EC) (10.67 ± 0.58 cm), Staphylococcus aureus (SA) (10.50 ± 0.40 cm), Pseudomonas aeruginosa (PA) (10.33 ± 0.58 cm), and Staphylococcus epidermidis (11 ± 1 cm) but not Bacillus subtilis (BS). The film's hue changed from red to green over time when used as a packaging material for meat under ambient condition indicating a deterioration in freshness. In conclusion, the developed packaging film exhibited enhanced mechanical, antimicrobial, and hydrophilic properties and it can be used to store and relay information when stored meat begins to decompose through a visible color change of the films.

Dataset Information

Uniformly Dispersed Poly(lactic acid)-Grafted Lignin Nanoparticles Enhance Antioxidant Activity and UV-Barrier Properties of Poly(lactic acid) Packaging Films.

Publications

Uniformly Dispersed Poly(lactic acid)-Grafted Lignin Nanoparticles Enhance Antioxidant Activity and UV-Barrier Properties of Poly(lactic acid) Packaging Films.

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