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People Films | Flexibles

People Films | Flexibles | Bags Compostable packaging nets Acknowledgements: The work received funding of CIP Eco-innovation program of European Community By Chelo Escrig-Rondán Head of Extrusion, AIMPLAS Paterna, Spain Steven Verstichel Head of BCE, OWS Gent, Belgium orldwide polyethylene nets are abundantly used for packaging organic products, such as potatoes, onions, green beans, garlic, shellfish, etc. However, the disposal of these nets causes problems to household waste treatment due their low apparent density and high strength (i.e. material is difficult to be cut and the nets may get entangled and collapse treatment machines). The ECOBIONET project tackles this end of life treatment problem by the development of compostable nets. The project aims to promote the industrialization of the process and technology of obtaining different types of biodegradable and compostable nets, obtained through the Extrusion Melt Spinning (EMS) process for the packaging of agricultural and shellfish products. The different types of nets collect most of the variations that are present in the market: Oriented nets which retain their original shape with the product inside: for garlic and shellfish products, for example) Non-oriented nets for citrus fruits, potatoes and a large variety of fruit and vegetables Combined nets designed to see the product and to let it breathe, but prevent waste and dust from falling out of the packaging. These nets have progressed from a biodegradable composite developed in a previous EU project (PICUS) to obtain non oriented nets. The innovations to be achieved throughout the development of the project were the following: Optimize an adequate biodegradable material for the manufacture of net packaging. Expansion of the use of biodegradable materials to oriented nets. Maintain the packaging weight, taking into account that the density of the biodegradable materials is 30% higher than polyolefins, while maintaining the mechanical resistance properties that the current nets have. The partners involved were research centre Aimplas, compostability testing lab OWS and producers Meseguer, Ecoplas and Tecnaro. New bio-compound developed for oriented nets In the ECOBIONET project two new grades of biodegradable materials (BM) were developed from commercial compostable 12 bioplastics MAGAZINE [06/13] Vol. 8

From Science & Research Figure1. Nets obtained for both applications. materials. The applied modifications have provided changes in rheological and mechanical properties that permit to achieve the desired characteristics. The key in this type of modifications is to define the best melt compounding system to achieve a homogeneous compound, taking into account rheological behavior of each biodegradable material and components, the compatibility between them, the melting temperature and processing. The equipment selected was a co-rotating extruder machine due to its modularity. During the project, the best screw configuration, defining the length and position of the transport and mixing (dispersive and distributive) elements and the feeding port for each component was defined. The compounds developed show the following properties in comparison with the target materials and the commercial biodegradable materials available in the market (Table 1). Industrial validation of the nets The BM developed has been processed in conventional equipment to obtain oriented nets for two applications: oriented nets for shellfish products and nets for garlic (Fig. 1). Finally, the nets obtained were validated taking into account the useful life of products, mussels and garlic during 16 and 20 days, respectively. After that the nets were characterized before and after the validation for comparative purposes. After the tested days, both nets showed good appearance and the changes are still acceptable (Table 2). Table1. Properties of the materials tested for nets manufacturing. MFR g/10 min (190°C , 2.16 kg) Maximum Tensile stress (MPa) Maximu, tensile Strain (%) Target material 0.2 - 1 10 - 25 400 - 600 Commercial BMs ECOBIONET BM > 1.5 35 - 60 5 - 10 ≈ 0.7 (*) 30 - 40 300 - 400 MFR determined according to EN-ISO 1133-1. Mechanical properties according to EN-ISO 527-3 (test specimen type 5, 50 mm/min) (*): MFR measured at process temperature, 150 ºC. Table2. Mechanical properties of the nets obtained. Type of nets Tested nets Net weight (g/m) Shellfish nets (5 ± 2) °C Oriented nets stored to: (23 ± 2) °C (50 ± 10) % RH Maximum Tensile stress(N) Elongation at break (%) Reference material 7,29 33,0 (1,5) 180 (12) BM before validation 34,6 (0,7) 52 (3) 7,06 BM after validation 31,8 (2,4) 46 (10) Reference material 11.6 15,1 (0.4) 150 (10) BM before validation 17,0 (0.8) 340 (21) 12.2 BM after validation 20,1 (1,4) 250 (17) Mechanical properties according to EN-ISO 527-3 (test specimen type 5, 50 mm/min) In bracket the standard deviation (s). bioplastics MAGAZINE [06/13] Vol. 8 13

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