e taken to drastically
e taken to drastically reduce the amount of plastic waste entering the environment in general – not just in Germany or the EU, but worldwide. The EU is pointing us in the right direction with its five-step waste hierarchy: reuse – reduce, recycle, incinerate (waste to energy) – (avoid) landfill. By: Roland Essel Head of Sustainability Department nova-Institute Hürth, Germany The nova-Institute is organising a conference entitled “Microplastics in the Environment – Sources, Consequences, Solutions” to take place on July 1st between 9am and 6pm at the Maternushaus conference centre in Cologne, Germany. Further information about the conference can be found at: www.bio-based.eu/mikroplastik References Arthur, C.; Baker, J. & H. Bamford (2009): Proceedings of the international Research Workshop on the Occurrence, Effects and Fate of Microplastic Marine Debris. Sept 9-11, 2008. NOAA Technical Memorandum NOS- QR&R-30. Barnes, D.K.A.; Galgani, F.; Thompson, R. C. & M. Barlaz (2009): Accumulation and fragmentation of plastic debris in global environment. In: Philosophical Transaction of the Royal Society B (biological sciences) 364: 1985-1998 Browne, M.A.; Crump, P.; Niven, S.J.; Teuten, E.; Tonkin, A.; Galloway, T. & R. Thompson (2011): Accumulation of Microplastic on Shorelines Worldwide: Sources and Sinks. In: Environmental Science & Technology 45: 9175-9179 CalRecycle – California Department of Resources Recycling and Recovery (2012): PLA and PHA Biodegradation in the Marine Environment. State of California, Department of Resources Recycling and Recovery, Sacramento, California Gouin, T.; Roche, N.; Lohmann, R. & G. Hodges (2011): A thermodynamic approach for assessing the environmental exposure of chemicals absorbed to microplastic. In: Environmental Science & Technology 45: 1466-1472 JRC – Joint Research Centre (2013): Guidance on Monitoring of Marine Litter in European Seas – A guidance document within the Common Implementation Strategy fort he Marine Strategy Framework Directive. MSFD Technical Subgroup on Marine Litter. European Union, 2013 Leslie, H.; van der Meulen, M. D.; Kleissen, F. M. & A. D. Vethaak (2011): Microplastic Litter in the Dutch Marine Environment – Providing facts and analysis for Dutch policymakers concerned with marine microplastic litter. Deltares, the Netherlands Narayan, R. (2009): Biodegradability... In: bioplastics MAGAZINE [01/09] Vol. 4: 28-31 PlasticsEurope – Association of Plastics Manufacturers (2013): Plastics – the Facts 2013. An analysis of European latest plastics production, demand and waste data. PlasticsEurope, Brussels Ryan, P.G.; Moore, C.J.; van Franeker, J.A. & C.L. Moloney (2010): Monitoring the abundance of plastic depbris in the marine environment. In: Philpsophical Transactions of the Royal Society B 364, pp: 1999 - 2012 STAP – Scientific and Technical Advisory Panel (2011): Marine Debris as a Global Environmental Problem: Introducing a solutions based framework focused on plastics. Global Environment Facility, Washington, DC. Teuten, E.L., Rowland, S.J., Galloway, T.S. & Richard C. Thompson (2007): Potential for plastics to transport hydrophobic contaminants. In Environmental Science and Technology 41, 7759-7764 Thompson, Richard C. (2014): The challenge: Plastics in the marine Environment. Environmental Toxicology and Chemistry 33: 6-8 UBA - Umweltbundesamt (2010): Abfälle im Meer – ein gravierendes ökologisches, ökonomisches und ästhetisches Problem. Umweltbundesamt, Dessau-Roßlau UNEP – United Nations Environment Programme (2006): Ecosystems and Biodiversity in Deep Waters and High Seas. UNEP Regional Seas Reports and Studies No. 178. UNEP /IUCN, Switzerland Wright, S. L.; Thompson, R. & T. S. Galloway (2013): The physical impacts of microplastics on marine organisms: A review. In: Environmental Pollution 177: 483-492 48 bioplastics MAGAZINE [02/14] Vol. 9
Basics Injection Moulding Injection moulding is a plastics processing technique for the fully automated production of plastic parts with complex geometries. Almost all sizes and shapes of plastic parts can be made by injection moulding. About 60% of all plastics processing machines are injection moulding machines [1]. Injection moulded parts range from a few milligrams (e.g. cogwheels in Swatch ® whatches) up to many kilograms (e.g. dashboards or bumpers for automobiles). The possible applications for injection moulding are almost endless. Some examples are ball-point pens, rulers and other office accessories, disposable cutlery, garden furniture, beverage crates, knobs and handles, small mechanical parts, and lots more. The process In the injection moulding process molten plastic material is injected into a mould. The granular plastic raw material for the part is fed by gravity from a hopper into a heated barrel. In this barrel the plastic material is transported forward by a turning screw. During this process the plastic is melted, mixed and homogenized. At the same time the crew slowly moves backward during the melting process to enable a shot of melted plastic to build up in front of the screw tip (Fig. 1). Once the quantity needed for one shot is reached the screw moves forward and presses the melt through a pre-heated nozzle and under pressure through the feed channel to the cavity of the cold mould, the so-called tool. The plastic now cools down in the tool and is ejected as a finished moulded part [1]. Injection moulding of bioplastics [4] In contrast to blown film production, which uses existing machinery that has already proved to be effective, some reservations still exist in terms of the injection moulding of bioplastics. Fig 1: The injection moulding process (picture: according to www.fenster-wiki.de) cooling heating screw granules plasticizing The most important requirement for successfully injection moulding bioplastics is the compatibility of existing production equipment. Frankly, existing machinery and production tools that are designed for common plastics such as PP, PS or ABS are perfectly suitable for the processing bioplastics (such as FKuR’s BIO-FLEX ® or BIOGRADE ® ) However, a small investment may be necessary concerning the hot runner system and the clearances within existing tools. One key to success is to reduce the residence time of the material. When compared with PS, for example, there are some bioplastics that can be processed with a reduction of 30% of the whole cycle time while others, such as PLA need longer cooling times due to the crystallisation process. While the mass temperature should not fall outside the defined temperature profile the processor should be informed, through recommended processing conditions, that the injection pressure and speed can be modified to fill the mould properly. The small processing window of bioplastics in terms of the temperature profile may result in the need for a new hot runner system. Commonly hot runner systems do not have a constant temperature along the whole length. This, along with the tendency of the materials to either freeze immediately or to burn if the temperature goes outside the processing window, can cause problems if improper hot runner systems are used. After resolving the issues of the hot runner by applying a suitable system then the only thing that the machine operator needs is a bioplastic grade designed for injection moulding (pre-dried if necessary) as well as a little practice with the new materials. Some examples of successful products made from FKuR’s bioplastics in both multi and single cavity tools with hot and cold runners are consumer electronics, office equipment and catering articles. MT References: [1]: Stitz, S.; Keller, W.: Spritzgießtechnik, Carl Hanser Publishers, 2001 [2]: Thielen,M.: Bioplastics - Basics. Applications. Markets, Polymedia Publisher, 2012 [3]: Wikipedia [4]: Lohr, C.: Bioplastics Designed for rigid parts, bioplastics MAGAZINE (Vol. 5) Issue 03/2010 mould melt drive injection, cooling with after-pressure demoulding Injection moulding machine (picture: Ferromatik Milacron) bioplastics MAGAZINE [03/14] Vol. 9 49
