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bioplasticsMAGAZINE_1306

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bioplasticsMAGAZINE_1306

Films | Flexibles | Bags

Films | Flexibles | Bags Plastics b.V. since 2005. The most important factor for Oerlemans Plastics in choosing the FKuR PLA mulch film was, among others, the unproblematic production of the film on conventional extruders, such as those used in the production of LDPE films. Before they went ahead with industrial production, the use of the Bio-Flex ® mulch film was successfully tested on a variety of crops by different research institutes and testing stations. Since 2005 Oerlemans Plastics‘ biodegradable PLA mulch films have been tested all over the world on a wide range of crops in various climate zones. The crop yields attained with this biofilm are comparable to conventional PE mulch films. Laying out the PLA mulch films can be done with the usual laying machines and is no more difficult than conventional biofilms. A big advantage over other biofilms, e.g. starch-based films, is its significantly slower decomposition and its resistance to fluctuating climatic conditions. Another advantage of bio mulch films in agriculture, is that the films can simply be ploughed into the soil after harvest, where they continue to degrade. The application of Bio-Flex mulch films reduces the amount of work required and lowers the costs of film disposal. The granules and the film are completely biodegradable in accordance with EN 13432. In addition, they are certified in accordance with DIN Certco, OK Compost, NFU 52001 und Ecocert. As mentioned above, the most important reason for the application of mulch film is weed suppression as a function of light absorption in the UV and visible (VIS) ranges. In addition, there is strong heat absorption (from the near infrared range NIR) because of the added carbon black. This means that the mulch film heats itself up and passes the absorbed heat on to its immediate environment. The second generation of mulch films represents the transition from LDPEbased film to films made of biodegradable plastics. Black carbon is still being used as pigment here. The focus is on sustainability through the guaranteed biodegradability in industrial composting. Heat absorption out in the open air really puts biodegradable mulch film to a hard test in terms of longevity and functionality. The idea of prolonging longevity by adding additives or aggregates would be in contradiction to the original goal of sustainability. Figure 2: Image of a standard mulch film colored with carbon black (1) as compared with an IRT-colored GRAFE mulch film (2 and 3). (Thanks to the friendly support of RKW). It was only a matter of time before studies began on colored, infrared transparent (IRT), biodegradable plastic mulch. The idea is to suppress weed growth through the complete absorption of lightwaves from the UV and the visible (VIS) ranges. However, the highest possible amount of energy from the near infrared (NIR) should be allowed to pass through. Figure 1 provides an overview of the UV-VIS-NIR spectra in transmission mode with dark colored mulch films (50 µm) made of various biodegradable plastics. It shows the continuous absorption from 200 nm to 750 nm and the increased transmission in the NIR range of values from 70% to 80%. It is obvious that this effect cannot be achieved with carbon black and this presents some disadvantages: The percentage of colorants used in thin films must be higher and this automatically increases the costs for raw materials. The color formulations that have been developed are based on the simple color mixture theory, which says that it is possible to create black (dark) colors by mixing a combination of pigments. Figure 2 shows the behavior of films that have been colored with black carbon against those that have been colored with IRT mixtures. The thermal imaging camera shows clearly the temperature differences under an infrared lamp. The advantages of using infrared transparent colors in mulch films can be summarized as follows: 20 bioplastics MAGAZINE [06/13] Vol. 8

From Science & Research High heat transmission This results in a higher soil / earth bank temperature Excellent conditions for plants that keep their roots in winter. No weeds or unwanted flora Reduced attacks from rodents and worms. Fruits, such as strawberries, are not damaged at contact points with overheated mulch film. No chemicals needed to suppress weeds and other vermin, enabling a change to organic farming. Earlier and increased yield. Improvement in crop quality – and amount. Based on these experiences, field tests were performed with tomatoes and cucumbers in 2012 with funds from the Thüringer Aufbaubank (Project Number 2010FE9048) at the Education and Research Institute for Horticulture Erfurt (LVG) The results are shown in the two figures below. Mulch films based on biodegradable plastics with IRT coloring were used in these field tests. LDPE-based standard black mulch films were compared to LDPE-based films with IRT coloring. The goal was to measure the effect of the films‘ biodegradability alone (PLA or cellulose) on the growth behavior of the crops. There are differences between the growth of the cucumbers and tomatoes. The data for the tomatoes show that in the early weeks all films independent of their composition display similar effects. In the later weeks, the PLA film with IRT coloring performs better than all the others. The differences, however, between the different film types are not significant. The field tests with the cucumbers, however, show differences from the beginning. The ranking of the yields from highest to lowest reads as follows: PLA + IRT, cellulose + IRT, LDPE + IRT and at the end the standard black mulch film can be found. Further tests (conducted by the Institute for Materials Research and Testing at the Bauhaus University Weimar MFPA) have confirmed the required minimum 90% biodegradability of the IRT-colored film in accordance with DIN EN ISO 14855-1. Ecotoxicity tests in accordance with DIN EN 13432 have also been successfully completed. On the basis of these tests, Bioflex F 1130 produced by FKuR has been selected as the most suitable material with a wide processing window and a high level of flexibility, independent of the machinery used. The combination with IRT color mixtures has resulted in a high-performance product representing the next generation of mulch film on today’s market. Figure 1: UV-VIS-NIR spectra of various biopolymeres in transmission mode %T Film Projects 2012 with Freeland tomato Marketable Harvest in weeks (kg) kg kg 80 70 60 50 40 30 20 10 0 200 300 400 500 600 700 800 900 1000 1100 1200 300 200 100 0 30 31 32 33 34 35 36 37 38 39 40 41 42 43 Film Project 2012 with cucumbers 700 600 500 400 300 200 Film PE LDPE MB FK (1) FK (2) Type PE LDPE UV 50 MB UV 50 FK (1) UV 50 FK (2) nm 11-07392.sp Film d = 0,05 mm 11-07392 CH-11-25522 11-07393.sp Film d = 0,05 mm 11-07393 CH-11-25523 11-07688.sp Film d = 0,05 mm 11-07688 CH-11-25524 Week Added Harvest (kg) 100 www.grafe.com 0 24 25 26 27 28 29 30 31 32 34 35 Week bioplastics MAGAZINE [06/13] Vol. 8 21

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