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Issue 05/2015

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  • Bioplastics
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  • Barrier
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Barrier Improvement of

Barrier Improvement of barrier properties on PLA-based packaging products By: Daniela Collin, Sabine Amberg-Schwab Fraunhofer-Institut für Silicatforschung Würzburg, Germany Victor Peinado, Berta Gonzalvo AITIIP Technological Centre Zaragoza, Spain Within the scope of the European Dibbiopack Project (7 th European Framework Programme; Grant agreement no: 280676), one of the main aims was the development of biodegradable films with improved barrier coatings as well as the investigations concerning the barrier properties of the bulk package using nanoparticles combined with the PLA material. This article is specially related to the development of barrier coatings on biodegradable PLA-based films. The Project The focus of the Dibbiopack Project was the development of new biobased materials specially adapted to the development of a wide range of containers or packages (films made by biaxially oriented blow moulding, trays and jars developed by injection moulding and bottles performed by extrusion blow moulding technologies) and the improvement of the thermal, mechanical and barrier properties of these packages by nanotechnology such as innovative coatings. Another main objective was the operational integration of different intelligent technologies or smart devices to provide the packaging value chain with more information about the products and the processes, increase safety and quality of products within the supply chain and improve the shelf-life of the packaged products. The project includes the design, development, optimization and manufacturing of multifunctional smart packages, assuring compliance of environmental requirements by means of LCA and LCC analysis, managing nanotechnology risk within the whole packaging value chain, and finally, end user evaluation in different sectors as cosmetic, pharmaceutic and food industry. The Partners 19 Partners form the consortium of Dibbiopack, which is headed by the Spanish AITIIP Technological Centre. Partners, which are dedicated to basic and applied research, are represented by institutes and universities such as Fraunhofer ISC, INSTM, TECOS or CNR to name a few. But also SMEs with research capabilities as Avanzare, Condensia Quimica, Archa or Plasma contribute with their knowledge to achieve the best biodegradable packaging possible to fit the needs of the end-user companies: Cosmetic, Help and Nutreco and, by extension, the possible needs of those markets regarding biobased packaging. The Achievements By the month 40 of the project (the project duration is 48 months), several goals have been achieved: • Optimized material formulations for nanoadditivated PLA, processing of these compositions by injection moulding and extrusion blow moulding, improved mechanical and barrier properties and processability than commercial grades. • Improved barrier properties on films which are built up by means of plasma surface application and functional coatings based on hybrid polymers. These barrier hybrid polymers are now also biodegradable. • Production processes were optimized at industrial level, with real demonstrators manufactured. Biodegradable ORMOCER – bioORMOCERs To increase the barrier properties of the packaging films, such as lids and polymer covers, additional coatings can be applied. Of course, in a biodegradable packaging system, these coatings should be biodegradable themselves. The development of biodegradable barrier coatings was one of the main objectives of the Fraunhofer-Institute for Silicate Research (ISC) in Würzburg, Germany, which has been working with a material class called ORMOCER ® s (registered trademark of the Fraunhofer-Gesellschaft für angewandte Forschung e. V., Munich) for more than 20 years. ORMOCERs are hybrid inorganic-organic polymers, which are synthesized via carefully controlled sol-gel reactions. The properties of these coating materials can be adjusted to the requirements of very specific applications, e. g. the coatings can have excellent 44 bioplastics MAGAZINE [05/15] Vol. 10

Barrier barrier properties. Especially when combined with inorganic thin-films the resulting barrier properties on flexible polymer substrates are outstanding due to synergistic effects. Within the framework of the Dibbiopack Project, Fraunhofer ISC has started its development of new biodegradable ORMOCER, so-called bioORMOCER ® s, which then can be added as a surface refinement of biodegradable polymer films to increase the water vapour and oxygen barrier properties. The basic concept of this development is the combination of typical ORMOCER precursors with modified biopolymers, the covalent cross-linking of these materials by strong covalent chemical bonds and the formation of a new hybrid polymer coating material. In combination with inorganic sputtered layers, developed by the consortium partner PLASMA, excellent barrier properties were achieved for these new surface refined polymer films. In detail, the water vapour transmission rate of pure PLA polymer films (provided by the consortium partner Innovia), which originally was > 500 g·m -2·d -1 was decreased below 0.15 g·m -2·d -1 in a sandwich setup of PLA substrate and PLASMA and bioORMOCER coating layers (testing conditions 23 °C, 100 % relative humidity). Comparative tests of this bioORMOCER layer setup on PET/ SiO x films (Ceramis from Amcor, cf. bM 03/2008 and bM 06/2012), PET film coated with SiO x layer by e-beam application) furthermore demonstrated oxygen barrier properties of 0.05 cm 3·m -2·d -1·bar -1 (23 °C, 50 % relative humiditiy). These surface refined polymer films furthermore passed the biodegradation test according to DIN ISO 148851:2005. In summary, a new material class, the bioORMOCERs, was developed within the DIBBIOPACK project. These novel functional coating materials can improve the properties of biodegradable polymer films. In this material concept, the rate of biodegradability can be further adjusted to meet the actual requirements in packaging solutions by the choice of biopolymer, the degree of functionalization and amount integrated within the polymer. Next to the barrier properties, additional features can be implemented within the bioORMOCERs such as antimicrobial characteristics or abrasion resistance. R 2 R 2 R 1 Inorganic component Hybrid polymer based on ORMOCER Organic component Modified biopolymer bioORMOCER bioplastics MAGAZINE [05/15] Vol. 10 45

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