ABSTRACT
Chitin nanofibrils (CN) can be obtained from crustaceans and fungal sources and can be used for preparing coatings for bioplastic films, that are fundamental for developing a safe and sustainable biodegradable food packaging. Coatings with different concentrations of CN from shrimps were applied on different bioplastic substrates, like Poly (butylene succinate-co-adipate)/Poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PBSA/PHBV) blend, Polybutylene succinate (PBS), and Polybutylene adipate terephthalate/Poly(lactic acid) (PBAT/PLA) blend, but the adhesion to the substrates was scarce. On the contrary, the fungal-based CN showed a better adhesion. Additionally, it was found that the use of an additive based on oligomeric lactic acid was useful to prepare a coating with an improved adhesion to bioplastics. The gas barrier properties to oxygen and water vapour of coated and un-coated films were measured, revealing an improvement of these properties thanks to applied coatings, especially towards the oxygen. Antimicrobial properties and biodegradation capacity were also evaluated revealing an antibacterial effect of the coatings that did not significantly interfere with their biodegradability. The results are discussed and interpreted considering the correlation between composition and macromolecular structures with the observed functional properties.
ABSTRACT
Biodegradable packaging materials are already in use. However, there are severe restrictions preventing the broad application in food packaging, especially due to insufficient barrier properties. Our idea was to improve these properties with a biodegradable coating. The Fraunhofer-Institut für Silicatforschung ISC has been developing high-barrier coatings for various packaging applications based on a class of materials with glass-like structural units, named ORMOCER®. However, these state-of-the-art ORMOCER® coatings are not biodegradable. The aim of our work was to modify ORMOCER® to become biodegradable and, at the same time, preserve the barrier and functional properties. This was achieved by the incorporation of functionalized tamarind hemicellulose Glyate® into the ORMOCER® matrix. For this purpose a two-step amination reaction of Glyate® was chosen. The aminated product was analyzed by FTIR, solid-state NMR and elemental analysis. New aminated Glyate® containing bioORMOCER® lacquers could be synthesized. Lacquer quality assessment was performed by Raman spectroscopy. The properties of the resulting coatings were evaluated by laser scanning microscopy (LSM), oxygen transmission rates (OTR) measurements, E-Module determination and adhesion tests. Standardized tests for compostability, overall migration and antimicrobial properties were performed for the bioORMOCER® coatings. The evaluation showed that the new bioORMOCER® coatings are suitable for sustainable food packaging.
ABSTRACT
Environmental impacts and consumer concerns have necessitated the study of bio-based materials as alternatives to petrochemicals for packaging applications. The purpose of this review is to summarize synthetic and non-synthetic materials feasible for packaging and textile applications, routes of upscaling, (industrial) applications, evaluation of sustainability, and end-of-life options. The outlined bio-based materials include polylactic acid, polyethylene furanoate, polybutylene succinate, and non-synthetically produced polymers such as polyhydrodyalkanoate, cellulose, starch, proteins, lipids, and waxes. Further emphasis is placed on modification techniques (coating and surface modification), biocomposites, multilayers, and additives used to adjust properties especially for barriers to gas and moisture and to tune their biodegradability. Overall, this review provides a holistic view of bio-based packaging material including processing, and an evaluation of the sustainability of and options for recycling. Thus, this review contributes to increasing the knowledge of available sustainable bio-based packaging material and enhancing the transfer of scientific results into applications.
