UV Protective, Antioxidant, Antibacterial and Compostable Polylactic Acid Composites Containing Pristine and Chemically Modified Lignin Nanoparticles

Abstract

Polylactic acid (PLA) films containing 1 wt % and 3 wt % of lignin nanoparticles (pristine (LNP), chemically modified with citric acid (caLNP) and acetylated (aLNP)) were prepared by extrusion and characterized in terms of their overall performance as food packaging materials. Morphological, mechanical, thermal, UV–Vis barrier, antioxidant and antibacterial properties were assayed; appropriate migration values in food simulants and disintegration in simulated composting conditions were also verified. The results obtained indicated that all lignin nanoparticles succeeded in conferring UV-blocking, antioxidant and antibacterial properties to the PLA films, especially at the higher filler loadings assayed. Chemical modification of the fillers partially reduced the UV protection and the antioxidant properties of the resulting composites, but it induced better nanoparticles dispersion, reduced aggregates size, enhanced ductility and improved aesthetic quality of the films through reduction of the characteristic dark color of lignin. Migration tests and disintegration assays of the nanocomposites in simulated composting conditions indicated that, irrespectively of their formulation, the multifunctional nanocomposite films prepared behaved similarly to neat PLA.

Active PLA Packaging Films: Effect of Processing and the Addition of Natural Antimicrobials and Antioxidants on Physical Properties, Release Kinetics, and Compostability

“…Color and opacity are two of the main optical properties to be evaluated during the development of active films, since noticeable changes in these parameters could negatively affect the consumer’s acceptability towards their application as food package materials [ 26 ]. PLA can be produced with high transparency, and mono- or several multilayer PLA films maintained this character regardless of the processing technique [ 7 , 27 , 28 ].…”

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

“…Blending PLA with lignin would provide a possibility to improve the antioxidant ,, and UV-barrier properties of the polymer. − PLA lignin blends, however, phase separate. ,− In addition to blending lignin, another approach to enhance the properties of PLA involves the incorporation of lignin nanoparticles. PLA–lignin nanoparticle blend films are attractive due to the small size and high surface-area-to-volume-ratio of the nanoparticles, which is interesting with respect to optical and antioxidant properties. − Lignin nanoparticles incorporated in PLA, however, also aggregate, which reduces the potential beneficial effects of their high surface-area-to-volume ratio on enhancing the properties of PLA and which may also impact the diffusion barrier properties of the composite.…”

Recent Advancements in Plastic Packaging Recycling: A Mini-Review

“…A gradual switch to biobased plastics has been witnessed by the increasing use at an industrial level of alternative raw materials [10,11] such as polylactic acid (PLA) [12], polybutyl succinate (PBS) [13,14], polyhydroxyalkanoate (PHA) [15][16][17], and polyethylene furanoate (PEF) [18][19][20], together with different composite materials produced from starch [21][22][23][24], CMC [25][26][27][28][29][30], wood [31,32], lignin [33,34], and many different agro-industrial wastes [35][36][37].…”