Barrier A multilayer
Barrier A multilayer cellulosic packaging with a bio‐based barrier Multilayer cellulosic packaging systems for food or beverages generally consist of paper or board and a polyethylene layer that is included to provide the necessary water barrier properties. Packaging systems for wet and dry products requiring higher barrier properties contain an additional aluminum foil layer, which extends the shelf life of the packed food. Cellulose is recycled at papermaking plants, which first grind and then repulp the recovered packaging material. A residual fraction, which can range from 30 % by weight for material in board‐based laminates and more for paper‐based laminates (making re‐ cycling of the latter impractical) is made up of aluminum and polyethylene, which can be used to injection mold low value applications. The cellulose fibers recovered from the glued laminate systems made up of layers of cellulose and polyethylene tend to be of low quality. Recycling is therefore not convenient – and composting not possible. By partially or totally replacing the polyethylene in such multilayer systems with a proteinmanagement based film, the end‐of‐life options would be considerably improved in T he BioBoard life cycle (source IRIS) terms of the environmental impact of post‐consumer packaging, as the different materials can be better separated or composted. The BIOBOARD European project [1] has been set up to examine the possible options for multilayer cellulosic based packaging. Previously, a protein‐based coating was found to improve the oxygen barrier properties of multilayer plastic films when produced by wet coating [2]. However, extrusion coating is normally used in the paper and board industries to assemble the cellulosic and plastic layers at high speed. As a preliminary step towards preparing the new multilayer packaging, the protein‐based layer was produced by flat die extrusion, a conventional method for producing plastic films, which can then be laminated to paper. However, the extrusion of proteins is a topic which is not yet fully understood from the scientific point of view. The controlled and reliable extrusion of proteins is quite challenging, as proteins tend to degrade when heated. Extensive studies on simple whey protein mixtures processed at lab scale [3] have shown that, in order to be able to extrude them, the proteins need to be modified to display a thermoplastic behaviour. Process parameters, such as temperature, plasticizer concentration, and processing time influence the properties. Within the scope of the Bioboard project, plastic formulations composed of waste proteins derived from the cheese or potato industry and biodegradable polyesters were developed and produced by twin screw extrusion. The process is of especial interest, as the plasticization of the protein, reactive modification, blending with biodegradable polyesters and the addition of potato pulp filler were optimised in a single extrusion step, thus making the process more sustainable from both an economic and environmental point of view. Interestingly, it was found that potato pulp, a by‐product of the starch industry that also contains fibers, can be used as a filler to increase the mechanical resistance of extruded whey protein‐based films [4]. The first application of the new biodegradable film was sought in multilayer cellulosic packaging, such as brick‐shaped packaging for beverages or pouches for dehydrated products, but it could also be applied in the production of flexible plastic packaging. The studies performed in the course of the project also showed that it was possible to modify the properties of the proteinbased blends, which means these also have potential for use in rigid packaging, such as thermoformable trays or containers. 46 bioplastics MAGAZINE [05/15] Vol. 10
Barrier While Bioboard offers a new, biobased, extrudable solution and contributes to the available knowledge about protein extrusion, it also exhibits good benefits in terms of the environment, as it is based on waste and promotes recycling and composting practices for post-consumer packaging. However, more research is needed to overcome the remaining hurdles, such as improving processability of the material so that it could be used industrially in packaging and no-packaging applications in the future. The author wishes to acknowledge the European Community‘s Seventh Framework Programme for Research, technological development and demonstration for co-funding the Bioboard European project [grant agreement nº 315313] [1] www.bioboard.eu [2] E. Bugnicourt, M. Schmid, O. Mc. Nerney, J. Wildner, L. Smykala, A. Lazzeri, P. Cinelli, “Processing and Validation of Whey-Protein-Coated Films and Laminates at Semi-Industrial Scale as Novel Recyclable Food Packaging Materials with Excellent Barrier Properties”, Advances in Materials Science and Engineering, vol. 2013, Article ID 496207, 10 pages, 2013 [3] V. M. Hernandez-Izquierdo and J. M. Krochta, “Thermoplastic processing of proteins for film formation - A review,” J. Food Sci., vol. 73, no. 2, pp. R30–R39, 2008. [4] M. Schmid, C. Herbst, K. Müller, A. Stäbler, D. Schlemmer, M.-B. Coltelli, and A. Lazzeri. “How potato pulp as filler in thermoplastic WPI/PBS Blends affects mechanical properties and water vapor transmission rate”, Polymer-Plastics Technology and Engineering, submitted, 2015 By: Maria-Beatrice Coltelli Researcher University of Pisa, Italy Elodie Bugnicourt Group Leader EcoMaterials Innovació i Recerca Industrial i Sostenible (IRIS) Castelldefels, Spain © Resysta Furniture and Decking (2), Faurecia, Tecnaro www.wpc-conference.com Sixth WPC & NFC Conference, Cologne Wood and Natural Fibre Composites 16 – 17 December 2015, Maritim Hotel, Germany World’s Largest WPC & NFC Conference in 2015! Market opportunities through intersectoral innovation in Wood-Plastic Composites and Natural Fibre Composites New applications – huge replacement potential in plastics and composites! ■ The international two-day programme, taking place in English ■ The world’s most comprehensive WPC exhibition ■ Vote for „The Wood and Natural Fibre Composite Award 2015“ ■ Gala dinner and other excellent networking opportunities Programme, Sponsors: Dr. Asta Eder asta.eder@nova-institut.de Organisation, Communication, Exhibition: Dominik Vogt dominik.vogt@nova-institut.de Organiser: nova-Institut GmbH Chemiepark Knapsack Industriestraße 300 50354 Hürth Germany bioplastics MAGAZINE [05/15] Vol. 10 47
