From Science & Research
From Science & Research New Developments in Environmentally Intelligent Bioplastic Additives & Compounds Advancing Bioplastics Controlled (soil) biodegradation CO 2 production in bioplastic-additive degradation trials 8.00 7.00 6.00 5.00 4.00 3.00 2.00 1.00 mmol CO 2 0.00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 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 Fig 2 PLA PLA 1 www.scionresearch.com Bioplastic with various additives Bioplastic only Impact strength PLA compounds Time (days) Article contributed by Dr. Alan Fernyhough, Unit Manager of the Bioplastics Engineering Group, Scion, Rotorua, New Zealand PLA 2 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 34 bioplastics MAGAZINE [01/07] Vol. 2
from Down-Under: Fig 3 all pictures: Scion 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 additives of potential use in bioplastics. Scion has developed 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. 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 4 bioplastics MAGAZINE [01/07] Vol. 2 35
