Starch foam technology

There is a long history to extract polymeric materials from renewable resources. Now focus has been given to the study of structure-function-biodegradability relationships, preparation of composites of natural with synthetic materials for improved properties and various applications, and development of processing technologies, such as foaming technology. Study and application of other abundant non-starch part of plants, natural fibers (jute, kenaf), oil, fats and proteins are active too. 

Pea is a renewable reservoir for functional macromolecules. Pea proteins or starches can be used for packaging applications, such as films, foams and controlled release systems. The functionality of the biopolymers is influenced by technological treatments and altered by physical, enzymatic or chemical modifications. This work is aimed at obtaining detailed knowledge about the structure-property relationships of pea-based biodegradable plastics. 

The combination of starch with a soluble polymer such as polyvinyl alcohol (PVOH) and/or polyalkylene glycols has been widely considered since 1970 [137]. In recent years the system, thermoplastic starch/PVOH has been mainly studied for producing starch-based loose fillers as a substitute for expanded polystyrene [138-144]. As an example, Altieri and Lacourse developed a technology based on hydroxypropylated high amylose starch containing small amounts of PVOH for improving foam resiliency and density [138-142]. In this case loose fillers were produced directly by a twin screw extruder. 

Leading producers with well established products in the market are Novamont, National Starch (main Novamont partner and licensee in the sector of loose-fills and of foamed sheets), and Biotec. Following the recent start-up of its third line dedicated to the production of Mater-Bi film grades in Terni, Novamont s internal production capacity is of 20000 tons/year. The total capacity, including the network of licensees in the sector of loose fills, is of about 35000 tons/year. The technology for the production of starch-based loose fills is licensed together with National Starch and Chemical Co. 

FIGURE 4.2 Scanning electron micrographs of extruded foams formulated as follows (a) 100% starch/PVA and (b) 70% starch/PVA, 2% chitosan, and 28% fibers. (From Debiagi F. et al., 2011, Brazilian Archives of Biology and Technology 54, 1043-1052.)... 

Debiagi, F., Mali, S., Grossmann, M. V. E., and Yamashita, F. 2011. Biodegradable foams based on starch, polyvinyl alcohol, chitosan and sugarcane fibers obtained by extrusion. Brazilian Archives of Biology and Technology 54 1043-1052. 

Guan, J. and Hanna, M. A. 2006. Selected morphological and functional properties of extruded acetylated starch-cellulose foams. Bioresource Technology 97 1716-1726. 

Schmidt, V. C. R. and Laurindo, J. B. 2010. Characterization of foams obtained from cassava starch, cellulose fibres and dolomitic limestone by a thermopressing process. Brazilian Archives of Biology and Technology 53 185-192. 

Novamont has been developing thermoplastic starch based polymers since 1990. Mater-Bi polymers are based on thermoplastic starch-blend technologies and product apphcations include biodegradable mulch films and bags, thermoformed packaging products, injection moulded items, personal hygiene items and packaging foam, [http //www.novamont.com/]... 

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