vor 7 Jahren

01 | 2010

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Foam BioFoam EPS

Foam BioFoam EPS Compressive strength (kPa) 40 g/l 200 30 g/l 200 Bending strength (kPa) 35 g/l 300 30 g/l 300 Young’s modulus (MPa) 40 g/l 4.0 30 g/l 3.0 C-value (-) 35 g/l 2.6 30 g/l 2.7 Thermal conductivity 35 g/l 34 30 g/l 33 (MW/m·K) Table 1 some physical ad thermal properties of BioFoam compared to EPS Article contributed by Jan Noordegraaf, Managing Director Synbra, Etten Leur, The Netherlands ‘Cradle to Cradle‘ Certified PLA Foam Synbra Technology bv in Etten-Leur, The Netherlands, is the Synbra Group‘s in-house polymerisation and ‘Technology & Innovation’ R&D facility, as well as the group‘s centre of excellence for materials and product development. Synbra is a leading European producer of Expandable Polystyrene (EPS) and the first plant (5000 t/a) to use a new polymerisation technology for PLA, that was recently developed by Sulzer Chemtech and Purac Biochem, will be built by Synbra Technology in the Netherlands for the production of BioFoam ® ; a foamed product made from this PLA (see bM 05/2008 and 01/2009). Processing The foam expansion process and moulding process for BioFoam is being developed at a rapid pace to facilitate approval of moulded prototypes. Parts are moulded every week for interested international customers. BioFoam processing has now left the laboratory phase and is running in series production for selected parts. The process of moulding is carefully adapted to suit expansion of the raw beads (called BioBeads) in existing EPS moulding equipment, resulting in uniform expanded beads and uniform cell structures (fig 1). A spherical and uniform series of raw beads in three classes (sized 0.6-0.7mm, 0.8- 1.0mm and 1.0-1.4mm) can be produced to suit the specific moulding application. With a slightly modified pre-expansion process and an industrial moulding machine existing moulds for EPS products were used to produce parts, see figures 2 and 4. Figure 1: SEM image of an expanded E-PLA bead, with a closed cell structure and a uniform cell size. Figure 2. Moulded parts, box and lid made in BioFoam for the logistics cool chain Properties The physical properties of BioFoam have been determined (see table 1) and are close to those of EPS. The thermal properties are strikingly similar, which has led to an interest in refrigerated transport for medical supplies. BioFoam is resistant to liquid nitrogen LN 2 and CO 2 granules or dry ice, the latter is often used in the transport cool chain, see figure 2. Of particular interest are the results for drop testing in comparison with EPS, which show that BioFoam has all the potential to become a good buffer material - a point that has not gone unnoticed by several blue chip companies, see figure 3 (a and b). BioFoam has a better resistance to high stress deformation as can been seen from its the characteristics in comparison with EPS. Carbon footprint Detailed information on the CO 2 balance of the PLA used by Synbra will be subject of a future article. In addition, a recent study was carried 24 bioplastics MAGAZINE [01/10] Vol. 5

Foam out comparing seed trays for growing plants made from BioFoam and from cardboard as two different material solutions. It was calculated how many grams of CO 2 would have been emitted to arrive at the same functional unit for BioFoam and cardboard. It was demonstrated that foams score better than the heavier part in cardboard, see figure 4. The part is a frequently used container for 15 bedding plants and weighs only 50 grams versus 200 grams in cardboard. Certification Being produced from the renewable resource PLA, BioFoam is an environmentally friendly alternative to the polystyrene foam products offered today. After use, the BioFoam product can be remoulded to a new product or can be completely biodegraded. Being ‘designed for the environment’ implies that there is no chemical waste, which means that the product is designed according to the so called ‘Cradle to Cradle’ principles. The Cradle to Cradle SM Design was founded by William Mc Donough and Michael Braungart. The latter is also the founder of EPEA (Environmental Protection Encouragement Agency), an international scientific research and consultancy institute based in Hamburg, Germany, that improves product quality, utility and environmental performance via eco-effectiveness. Together with their USA based sister company MBDC (McDonough Braungart Design Chemistry LLC), EPEA is able to grant companies a Cradle to Cradle certificate for specific products. Synbra actively encourages its suppliers to embrace the C2C scheme. Tebodin Consultants & Engineers of The Netherlands (who have a cooperation agreement with EPEA ) was asked to prepare the application package for the Cradle to Cradle certification of BioFoam. Data was collected and compiled on material safety, water and energy utilisation, as well as information on the social responsibility of the applying company. Based on this information EPEA was able to carry out an assessment study, which has resulted in BioFoam now being officially declared a Cradle to Cradle Certified material. This is the first PLA based product in the world and the first biodegradable foam in the world with this certification. The PLA Bio-Beads made by Synbra have in the meanwhile also been certified, effectively making it the first PLA polymer to be C2C certified in the world.. average drop 2-5, drop height 76 cm G (-) 80,000 70,000 60,000 50,000 40,000 30,000 20,000 10,000 0,000 0 5,00 10,00 15,00 20,00 25,00 30,00 Static stress (kPa) EPS 20 E-PLA 60 E-PLA 35 Figure 3a. Drop testing: G-force versus static stress energy for EPS and two densities of 60 and 35 gr/l E-PLA for single drop testing. 1st drop 76 cm height G (-) 80,000 70,000 60,000 50,000 40,000 30,000 20,000 10,000 0,000 0 5,00 10,00 15,00 20,00 25,00 30,00 Static stress (kPa) EPS 20 E-PLA 60 E-PLA 35 Figure 3b. Drop testing: G-force versus static stress energy for EPS and two densities of 60 and 35 gr/l E-PLA for multiple drop testing Conclusion BioFoam mouldings are based on renewable feedstock that allow a major saving in CO 2 emission compared to equivalent functional units. Clearly this explains why it is attractive to a whole range of industries. The particle foam nature of the material allows a very wide freedom of design with the convenience hitherto only offered by EPS. kg CO 2 emmision / part (100 year CO 2 equiv) BioFoam (lactide based) Cardboard 0,04 0,06 0,08 0,10 0,12 0,14 0,16 Figure 4: Parts analysed for the comparative study and the CO 2 emission originating from its production for the same functional unit. bioplastics MAGAZINE [01/10] Vol. 5 25

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