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Issue 04/2015

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  • Biodegradable

Blow moulding New

Blow moulding New biodegradable packages for dairy products The aim of the European BIOBOTTLE project is to develop new biodegradable materials suitable to produce monolayer and multilayer plastic bottles and pouches for packaging different types of dairy products (e. g. fresh milk, pasteurized milk and UHT dairy products), that offer the same shelf life as traditional packages. At the same time they should be compostable after their use without having to empty and clean them. With an average of 261 kg per year (FAO, 2011), the European countries are the biggest consumers of dairy products in the world. The packaging materials used are completely recyclable and the post-consumer waste management should not be a problem. However, in fact only about 10 % to 15 % are actually being recycled (according to 2012 data). In addition recycling of such packaging requires exhaustive washing to eliminate any product and/or residual subsequent odors. Therefore, it is especially interesting for the dairy industry to develop packaging products that can be composted together with their own residues using organic wastes. The different packaging types to be developed within the project, must fulfill different characteristics in terms of thermal, mechanical, microbiological or organoleptic properties, depending on the type of dairy products and their required shelf-life. Table 1 summarizes some of these specific requirements. One of the main difficulties with which the researchers of this project must deal, is that the traditional packages used today require thermal treatments such as sterilization or pasteurization. Some of the commercially available biodegradable materials show thermal resistances of up to approx. 65 °C whereas the current thermal treatments reach temperatures up to 90 – 95 °C. The packaging products to be developed shall fulfill the following requirements: • Guarantee the properties of dairy products throughout their shelf-life. • Ensure mechanical and thermal properties similar to the current materials used. • Be processed on conventional processing equipment. • Be fully biodegradable under composting conditions, according to ISO 14885, EN 13432 • Be suitable for use as a fertilizer, according to the compostability standard EN 13432. • Be competitive, in comparison to the current packaging materials. • Be suitable for food contact. • Maintain the organoleptic properties, such as aroma (smell), colour, taste and texture. The development scheme in figure 1 shows the work being carried out in the BIOBOTTLE project: Partners Seven companies and technological centers from five different countries comprise the consortium which is being coordinated by AIMPLAS; Germany (VLB), Belgium (OWS), Italy (CNR), Portugal (VIZELPAS and ESPAÇOPLAS) and Spain (ALMUPLAS and ALJUAN). The Plastics Technology Center AIMPLAS (Valencia, Spain) is a non-profit research association acting as a technological partner with companies in all sectors related to plastics, customizing integral and personalized solutions through the coordination of R&D projects and technological services (analysis, testing, technical assistance, competitive and strategic intelligence and training). Project development The project has now run halfway down its expected shelflife and during the first period some chemical modifications have been carried out on different biodegradable materials (based on PLA) available in the market. The materials obtained at pilot plant level were studied in order to assess their processability in both conventional extrusion lines; extrusion blow molding and blown film extrusion to obtain pouches and bottles respectively. Table 1: Requirements of the selected dairy products to be studied. Fresh milk (flexible pouches) Probiotic yougurt products (bottles) Organic UHT milk (bottles) Required shelf-life 4 – 7 days at

The materials and final products obtained at pilot plant level with the biodegradable materials developed were modified by a crosslinking reaction in the reactive extrusion step in order to get a branched polymer with enhanced thermal properties. During this reactive extrusion process a reticulate agent was added to promote the radical reaction of the polymer chain. These radicals are necessary for the branching process between polymer chains to occur. The products were characterized and the results are shown in tables 2 (for bags/ pouches) and 3 (bottles). Additionally, for caps/closures for bottles, new biodegradable blends were obtained taking into account their processability by injection moulding. Table 4 shows the hardness range of these blends in comparison with the reference material, polypropylene (PP). Biodegradability The biodegradability tests were carried out with the new developments and first measurements showed good results. Other tests to evaluate the compostability are exhibiting ongoing promising results. Future steps In the second part of the project, the packaging characterization (pouches and bottles) will continue and their validation will start taking into account their functionality regarding microbiological analysis, migration and organoleptic aspects. On the other hand, the scale-up of new bio-compounds and the obtaining of pouches, bottles (monolayer and multilayer) and caps will be carried out. Acknowledgement This project has received funding from the European Union´s Seventh Programme for Research, Technological Development and Demonstration (FP7 / 2007 – 2013) under grant agreement nº [606350]. By: Chelo Escrig Rondán Head of Extrusion Department AIMPLAS (Technological Institute of Plastics) Figure 1: BIOBOTTLE planned scheme of work Biodegradable grades Reticulate agents Chemical modification by reactive extrusion Extrusion process, monolayer and multilayer blown film and extrusion blow moulding, injection moulding for caps Table 4: Hardness of the new developments Properties Standard Paterna, Spain Final products Pouches by blown film extrusion Bottles by extrusion blow moulding: - Small bottles, probiotic products - Big bottles for milk Reference material New developments Hardness (Shore D) EN ISO 868 69 – 72 65 – 77 Table 2: Thermal and mechanical properties in bags. Properties Table 3: Thermal and mechanical properties in bottles. Standard Reference material Commercial bio-material New developments Thermal UNE-EN Vicat temperature (°C) 100 – 115 62 – 70 90 – 100 resistance ISO 306 UNE-EN Stress at break (MPa) 17 – 20 18 – 34 18 – 32 ISO 527-2 Mechanical UNE-EN Elongation at break (%) 850 – 940 550 – 750 650 – 800 properties * ISO 527-2 UNE-EN Puncture resistance (mJ) 2 – 3 3 – 4 4,5 – 5,5 14477 (*) Mechanical properties were measured in 125 microns film. Properties Thermal resistance Mechanical Properties (*) Maximum stress 10 N. Vicat Temperature (ºC) Stress at break (MPa) Elongation at break (%) Compression Standard UNE-EN ISO 306 UNE-EN ISO 527-2 UNE-EN ISO 527-2 Internal procedure (*) Reference material Commercial bio-material New developments 110 – 125 62 – 70 90 – 100 25 – 30 28 – 40 29 – 34 650 – 800 530 – 750 500 – 700 No break No break No break bioplastics MAGAZINE [04/15] Vol. 10 23

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