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Basics Fig.3: Mater-Bi

Basics Fig.3: Mater-Bi technology: droplike structure The products based on starch/EVOH show mechanical properties good enough to meet the needs of specific industrial applications. Their moldability in film blowing, injection molding, blow-molding, thermoforming, foaming, etc is comparable with that of traditional plastics such as PS, ABS, and LDPE [11]. The main limits of these materials are in their high sensitivity to low humidities, with consequent enbrittlement. The biodegradation of these composites has been demonstrated in different environments [12]. A substantially different biodegradation mechanism for the two components has been observed: Fig. 5: Foamed loose fill Bibliography [1] G. J. L. Griffin, U.S. Pat. 4016117 (1977). [2] G. Scott, U.K. Pat. 1,356,107 (1971). [3] J. W. Donovan, Biopolymers 18, 263 (1979). [4] P. Colonna and C. Mercier, Phytochemistry 24(8), 1667–1674 (1985). [5] J. Silbiger, J. P. Sacchetto, and D. J. Lentz, Eur. Pat. Appl. 0 404 728 (1990). [6] C. Bastioli, V. Bellotti, and G. F. Del Tredici, Eur. Pat. Appl. WO 91/02025 (1991). [7] P. Le Bail, C. Rondeau, and A. Buléon,, Int. Journal of Biological Macromolecules 35 (2005), 1-7 [8] J.L:Willett, B.K: Jasberg, C.L: Swanson,, Polymer Engineering and Science 35 (2), 202- 210 (2004) [9] F. H. Otey, U.S. Pat. 4133784 (1979). [10] C. Bastioli, V. Bellotti, M. Camia, L. Del Giudice, and A. Rallis “Biodegradable Plastics and Polymers” in Y. Doi, K. Fukuda, Ed., Elsevier, 1994, pp. 200–213. [11] C. Bastioli, V. Bellotti, and A. Rallis, “Microstructure and Melt Flow Behaviour of a Starch-based Polymer,” Rheologica Acta 33, 307–316 (1994). [12] C. Bastioli, V. Bellotti, L. Del Giudice, and G. Gilli, J. Environ. Polym. Degradation 1(3), 181–191 (1993). [13] C. Bastioli, V. Bellotti, G. F. Del Tredici, R. Lombi, A. Montino, and R. Ponti, Internatl. Pat. Appl. WO 92/19680, (1992). • The natural component, even if significantly shielded by an ‘interpenetrated‘ structure of vinyl alcohol, seems, first, hydrolysed by extracellular enzymes. • The synthetic component seems biodegraded through a superficial adsorption of micro-organisms, made easier by the increase of available surface that occurred during the hydrolysis of the natural component. The degradation rate of 2–3 years in watery environments remains too slow to consider these materials as compostable. Aliphatic polyesters/thermoplastic starch Starch can also be destructurised in the presence of more hydrophobic polymers, totally incompatible with starch, such as aliphatic polyesters [13]. It is known that aliphatic polyesters having a low melting point are difficult to process by conventional techniques for thermoplastic materials, such as film blowing and blow molding. It has been found that the blending of starch with aliphatic polyesters allows an improvement of their processability and their biodegradability. Particularly suitable polyesters considered in the past have been poly-e-caprolactone and its copolymers, or polymers at higher melting point formed by the reaction of glycols as 1,4-butandiol with succinic acid or with sebacic acid, adipic acid, azelaic acid, dodecanoic acid, or brassilic acid. The presence of compatibilizers between starch and aliphatic polyesters such as amylose/EVOH V- type complexes [10], starch grafted polyesters, and chain extenders such as diisocyanates, and epoxydes is preferred. Such materials are characterised by excellent compostability, excellent mechanical properties, and reduced sensitivity to water. Thermoplastic starch can also be blended with polyolefines, possibly in the presence of a compatibilizer. Starch/cellulose derivative systems are also reported in the literature [12]. The combination of starch with a soluble polymer such as polyvinyl 44 bioplastics MAGAZINE [05/09] Vol. 4

Fig.4: Mater-Bi technology: layered structure alcohol (PVOH) and/or polyalkylene glycols has been widely considered since 1970. In recent years the thermoplastic starch/PVOH system has been studied, mainly for producing starch-based loose fillers as a replacement for expanded polystyrene. Micro- and Nanostructured Composites The most important achievement of recent years in the sector of starch technology is seen in the creation of micro and nanostructured composites of starch with polyesters of different types and particularly with aliphatic-aromatic polyesters and with rubber. This technology has been developed and patented by Novamont. In these families of products starch gives a technical contribution to the mechanical performance of the finished products in terms of increased toughness and excellent stability at different humidities and temperatures. With this generation of products it is possible to cover a wide range of demanding applications in the film sector and to meet the different needs of end-of-life conditions up to home compostability and soil biodegradation. Moreover, it is possible to obtain low hysteresis rubber for low rolling-resistance treads in tyres. The last developments in this sector have been achieved within the EU Biotyres project which has led Goodyear to produce the tyres used in the new BMW 1-series models. The development of aliphatic and aliphatic-aromatic copolyesters containing monomers from vegetable oils, covered by a new range of Novamont’s patents, has further improved and widened the performances of these products from an environmental and technical point of view. Such development has justified the significant industrial investment made by Novamont to build the first local biorefinery of this type in Europe, which comprises plants for the production of nanostructured starch and polyesters from vegetable oils. Moreover new investments in monomers from vegetable oils from local crops will permit a further up-stream integration of the biorefinery. This family of tailor-made products has permitted Novamont to work on many case studies aimed at demonstrating the opportunity offered by biodegradable and bio-based plastics to rethink entire application sectors, thereby affecting not only the manner in which raw materials are produced, but also permitting verticalisation of entire agro-industrial non-food chains, or which are synergistic with food, and the way in which products are used and disposed of, expanding the scope of experimentation to local areas. This is the way Novamont believes bio-plastics may become a powerful, largescale case study for sustainable development and cultural growth - a real example of transition from a product-based to a system-based economy. Fig. 6: Biotyre bioplastics MAGAZINE [05/09] Vol. 4 45

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