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Issue 01/2017

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10 Years ago From

10 Years ago From Science & Research Controlled (soil) biodegradation Published in bioplastics MAGAZINE In Jan 2017, Kate Parker (Zealafoam) says: “The ten years since first introducing our PLA foaming technology have been an exciting and busy period for the Biopolymer Network Limited (BPN) team from New Zealand. Over that time BPN has continued working on their patented process for making Zealafoam ® , a PLA based alternative to expanded polystyrene (EPS), which uses CO 2 as a green blowing agent to produce low density particle PLA foam. Advances have been made in base material with work focussed on optimisation of PLA grades, blends and additives (bM 01/13). Cost-effective biomass fillers have shown excellent results in producing novel foams. A focus on commercialisation has led to a multitude of industry trials worldwide (bM 01/11) allowing us to prove our technology on a range of existing foaming and moulding machines. This has enabled us to address issues around commercial production. It has also led to foams of lower density with moulded products under 20 g/l being achieved. Applications today include products ranging from loose bead (used in furniture and loose fill packaging), to fish boxes and cycle helmets. The next stages for the research team include leveraging this technology for other product lines including foamed cups and thin, lightweight labelling film (bM 01/16).” Advancing Bioplastics from Down-Under: CO 2 production in bioplastic-additive degradation trials mmol CO 2 8.00 7.00 6.00 5.00 4.00 3.00 2.00 1.00 0.00 Fig 1 Impact Resistance (kJ/m 2 ) 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 PLA Fig 2 Bioplastic with various additives Bioplastic only PLA 1 PLA 2 New Developments in Environmentally Intelligent Bioplastic Additives & Compounds Advancing Bioplastics from Down-Under: Time (days) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Impact strength PLA compounds Article contributed by Dr. Alan Fernyhough, Unit Manager of the Bioplastics Engineering Group, Scion, Rotorua, New Zealand PLA 3 Scion, based in Rotorua, New Zealand, is a research organisation with approx. 390 employees firmly focused on a biomaterials future and has been working with bioplastics for about 10 years. Scion recognised at an early stage that bioplastics represented a huge opportunity for New Zealand, with its traditional strengths in all aspects of the agriculture, horticulture, and forestry industries’ value chains. Each year large volumes of a wide range of biomasses are processed for an increasing range of end uses in New Zealand. Such resources, and the residues from the harvesting and downstream processing, represent valuable sources of fibres, fillers, polymers and functional chemical additives for use in industrial biopolymer products, such as bioplastics. The core focus of Scion has been on additives and compounding formulations for enhanced performance in commercial bioplastics. One of the early areas of research was the compatibilised combination of wood and other natural fibres with a range of commercial bioplastics such as MaterBi, Solanyl, Biopol (PHA), PLA and others. Scion then developed a novel technology for wood-fibre (as opposed to wood flour) pellet manufacture for bioplastics compounding and moulding- showing markedly superior performance to wood flour and to agri-fibre reinforced bioplastics. A database of properties and formulations for a wide range of biobased additives, fillers/fibres, compatibilisers etc was established with data on mechanical properties, processability, water and biodegradation responses, durability/weathering (UV/humidity) and other properties such as flame retardancy. Now the database comprises in excess of 300 formulations with such data, using major commercial bioplastics, variously compounded with novel (biobased) additives, or combinations of additives, sourced primarily from readily available biomasses. With moulders and compounders Scion is developing several applications in New Zealand, ranging from controllably degradable plant pots, erosion control products, underground temporary fixtures, office furniture and stationery products. The knowhow in enhancing bioplastics performance, together with an ability to control the degradation (accelerate or decelerate) profiles of commercial bioplastics, in soil and aqueous media, is now being applied to such product developments. Most interest has been for injection moulding, but there is increasing interest in extrusions and thermoforming. Examples of some of Scion’s developments are: Controlled Degradation Compounds The biodegradation of PLA and other bioplastics in soil media can be controlled by (biobased) additive technologies, while maintaining processability and mechanical integrity. For example Figure 1 shows examples of different biodegradation profiles, in soil, of PLA compounds with the addition of biomass additive systems, selected from the database. High Impact PLA Another outcome from Scions screening work has been clues to improving the impact resistance of brittle bioplastics, such as PLA. While it is relatively straightforward to improve stiffness and strength in PLA, for example by compatibilised addition of natural fibres or fillers, it is less easy to improve impact strength at the same time. However, researchers at Scion have identified some approaches which can do this. Figure 2 shows example data on impact strength for some injection moulded PLA formulations. Visualising Biopolymers in Natural Fibres A unique approach to ‘track’ biopolymers in moulded compounds has been developed by Dr Grigsby and Armin Thumm. Natural fibres differ from glass and carbon fibres in that they are permeable, and have cell walls and hollow centres of various dimensions (lumen). Confocal microscopy has been applied (Figure 3) to visualise differences in interfacial behaviours, at a fibre cell wall level. Use of selected flow modifiers, and/or certain processing conditions can lead to lower instances of voids between the biopolymer and fibre, and, can promote (or reduce) lumen filling. The implications of such differences on properties are being evaluated. New Functional Additives for Bioplastics Scion continues to screen biomass streams for functional Biofoam Developments Work on biofoams has focused on a new PLA foaming technology which uses carbon dioxide as blowing agent. Dr Witt has led this work and developed novel routes to the manufacture of very low density moulded blocks (~20g/l; Figure 4). Scion also works with a major foam moulder in New Zealand to further develop their bioplastic foaming technology for packaging products. Much of this is undertaken within Biopolymer Network Ltd, a JV between Scion and two other NZ research institutes, AgResearch and Crop & Food Research. About Scion Scion was established in 1947 as the New Zealand Forest Research Institute. From its forestry science roots, the government-owned Institute branched out into other areas of research: exploring the potential of trees, and other plants, crops and biomass residues to produce new bio-based materials. To mark this shift in emphasis, the organisation changed its trading name to “Scion”, which refers to a piece of plant material that is grafted onto an established rootstock. This new name symbolises the growth of research towards a future world where bio-based materials are required to replace non-renewable synthetics. This article could only give a condensed and incomplete overview of Scions activities. In future issues bioplastics MAG- AZINE will address one or the other activity in more detail. Fig 3 all pictures: Scion Fig 4 additives of potential use in bioplastics. Scion has developed 34 bioplastics MAGAZINE [01/07] Vol. 2 extractions, fractionations and derivatisations of such extracts and has developed novel ways of using them. For example, they can be used as components in high performance adhesive formulations and as functional additives for bioplastic compounds. bioplastics MAGAZINE [01/07] Vol. 2 35 40 bioplastics MAGAZINE [01/17] Vol. 12

Basics Can additives make plastics biodegradable? By: Constance Ißbrücker European Bioplastics Berlin Germany Biodegradability is an inherent property of a material or product resulting from the action of naturally occurring microorganisms, such as bacteria, fungi, and algae. The process produces water, carbon dioxide, and biomass. No additives are needed and no fragments remain in the environment. In the case of industrial composting, the requirements are clearly defined in internationally agreed standards such as EN13432, or ISO 18606. For biodegradation in other environments other standards can and should regulate the framework conditions and pass/fail criteria. So-called oxo-degradable plastics are commonly fossil-based, non-biodegradable polyolefins or polyesters (e.g. PE or PET) supplemented with salts of transition metals. These additives are supposed to enable the biodegradation of apparently nonbiodegradable plastics. However, to date no reproducible study could provide satisfactory evidence for this, for example by measuring a significant amount of carbon dioxide evolvement, which is the standard indicator of and verification method for biodegradation. Publications in support of oxo-degradable plastics have claimed about 60% biodegradation in two years, leaving the fate of the remaining 40% up to speculation. Apart from the comparatively long time span (EN 13432 requires 90% disintegration in 12 weeks and biodegradation of 90% within six months), there are serious implications: It is assumed that oxo-degradable materials only disintegrate and finally visibly disappear under the influence of light (UV radiation) and oxygen. If no real biodegradation takes place simultaneously and subsequently, the process of disintegration results in the formation of invisible plastic fragments, contributing to the ubiquitous environmental and health hazard of microplastics in the environment. Another group of plastic materials supplemented with additives that are supposed to support biodegradation are so-called enzyme-mediated plastics. Naturally occurring biodegradation relies on enzymatic reactions initiated by naturally present organisms. The producers of enzyme-mediated plastics intend to emulate the process of biodegradation by adding enzymes to conventional polyolefins. So far no independent study or publication shows any positive results for such materials with regard to biodegradation, even though most of the producing companies are claiming that their plastics are 100% biodegradable or even compliant with accepted composting standards. These claims are often made not on the basis of conversion to carbon dioxide, but instead on the basis of mass loss, which is no scientific proof of biodegradation taking place. It is important to clearly differentiate between different concepts in this context: Enzyme-mediated plastics should not be confused with recent promising research efforts focussing on a kind of enzymatic recycling. In the latter case waste of conventional plastics (e.g. PET or PU) waste are depolymerised through tailor-made enzymes. The obtained monomers then can function as raw material for the production of bioplastics such as PHA, which is biodegradable in numerous environments without the use of any supporting additives. Home Compostable* Mailing Film * According to OK Compost Home and NF T51-800 (11-2015) NEW Bio4Pack GmbH • PO Box 5007 • D-48419 Rheine • Germany T +49 (0) 5975 955 94 57 • bioplastics MAGAZINE [01/17] Vol. 12 41

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