Starch based polymer

Starch-based biodegradable polymers have been introduced in order to enhance the properties and applications of starch. Starch has been physically or chemically modified with synthetic degradable polymeric materials by using various methods such as blending, derivation, and copolymerization. Numerous polymers (mainly biodegradable), including polyesters and biopolymers, have been blended with starch to produce starch-based biodegradable polymers. 

The life cycle included raw material acquisition, the production and processing and/or disposal of bags as well as routes of transport. Packaging, distribution, utilization and collection as well as transport to wholesalers could not be considered due to dependency of these processes on the prospective bulk buyers and retailers [25], Paper bags haushalt compost , which can be composted, and PE multipurpose bags, which cannot be composted, were used as points of reference. It is not relevant to the overall results whether maize produced in Switzerland or in France is used. Mater-Bi bags made of French maize were selected for the overall assessment as maize on the European market is mainly produced in France. 

Energy consumption of energy resources (oil, natural gas, etc.), assessed from the energy content of the resources necessary (MJ) 

Greenhouse effect temperature increase of the planet due to gas emissions (CO2 equivalents) 

Environmental impact category Bag made of Mater-Bri compared with  

Acidification potential damage to plants due to the emission of substances such as nitrogen and sulphur oxides (SO2 equivalents) 

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Torres et al. (2006) reported a novel microwave processing technique to produce biodegradable scaffolds for tissue engineering from different types of starch-based polymers. Potato, sweet potato, com starch, and non-isolated amaranth and quinoa starch were used along with water and glycerol as plasticizers to produce porous stmctures. Figure 16.1 shows the manufacturing procedure of microwaved starch scaffolds. 

The focus of this work was to determine if a glyco-peptide or a simple dextrinized, oxidized starch could be produced which would enhance the behavior of a starch-based polymer for spray dried flavoring production. Enhancement of a starch s lipophilic/hydrophilic balance was anticipated to maintain the polymer s film forming" and cohesive wall development during the spray drying process while improving its emulsifying/interfacial activity capabilities. 

Of the myriad of modified starch systems tested, ranging from simple enzymically dextrinized starches to covalently attached amino acids and peptides onto dextrinized and/or oxidized (hypochlorite or periodate) corn starch bases, two polymers were selected as holding promise. The first system was a low dextrose equivalent (DE 5.7) enzyme-modified corn starch. The second starch-based polymer developed was a periodate-oxidized, amylase-dextrinized, covalently-attached phenylalanine glycoamine. 

There is also US research interest in using pectin in polymer applications. Pectin is a complex plant cell wall heteropolysaccharide (based on galactose, rhamnose, arabinose and xylose) that can be blended with synthetic polyvinyl alcohol (PVA) to produce biodegradable polymers with a wider range of properties than those of starch-based polymers alone. The new pectin/PVA biodegradable polymer should be capable of replacing conventional PVA applications in blow-moulded, extruded, film and injection-moulded applications. 

Starch has been considered an attractive raw material for polymer applications for almost 200 years. Kirchoff s discovery in 1811 that treatment of starch with an acid yields a sweet substance was an unexpected result of the search for a low-cost substitute for natural rubber.1 Considerable research in the development of starch-based polymer materials has been stimulated by the facts that starch is produced from wide variety of sources, is an annually renewable resource and is inherently biodegradable. 

In nature, the availability of starch is just second to cellulose. The most important industrial sources of starch are corn, wheat, potato, tapioca and rice. In the last decade, there has been a significant reduction in the price of corn and potato starch, both in Europe and the USA. The lower price and greater availability of starch associated with its very favourable environmental profile aroused a renewed interest in development of starch-based polymers as an alternative to polymers based on petrochemicals. 

Most biodegradable polymers can be used for making injection moulded articles. Starch-based polymers are used to manufacture a wide range of items such as pencil sharpeners, rulers, cartridges, combs and toys, plant pots and bones. 

Polylactide (PLA) is the leading polymer type among biodegradables with global production capacity for this material amounting to about 250,000 tonnes per annum in 2005. Starch-based polymer capacity is approaching 60,000 tonnes per annum. 

Italian company Novamont has since emerged as the leading supplier of starch-based polymers. Novamont started its research activities in 1989 as part of the Montedison group and its Mater-Bi polymers were commercialised in 1990 with the opening of a 4,000 tonnes per annum plant at Terni in Italy. Novamont further consolidated its leading position in starch-based polymers in 1997 with the acquisition of worldwide patents belonging to Warner-Lambert and has continued to grow the business very successfully since then. 

Starch-based polymers can be based on crops such as com (maize), wheat, or potatoes. Starch content may range from 10% to >90%, but significant material breakdown occurs above 60%. As the starch content increases, the polymer compos-... 

The decrease in expansion seems to occur at moisture levels above 30°/o moisture for both cereal (starch-based) polymer systems, and protein (soy grits). This corresponds to a point on their adsorption curves where water activity rises rapidly with added moisture that is, at a level where the water added to a mix has little effect on primary hydration of polymers, but behaves as a diluent. In mechanical terms, this may be explained by proposing that at above levels of 25°/o-30% water plasticisation of the polymers is complete, and further added water acts as a lubricant, reducing the shear-induced temperature rise and particle damage necessary for the formation of homogeneous melts. 

It is clear that research into modifications to thermoplastic starch based polymers is burgeoning and that property and processing improvements derived from this research will help thermoplastic starch polymers widen their application products and markets. 

Clearly thermoplastic starch based polymers offer a very attractive base for new biodegradable polymers due to their low material cost and ability to be processed on conventional plastic processing equipment. The engineering of more advanced properties into these low cost base materials will continue to be... 

Bastioli C, Belloti V, Rallis A (1994) Microstructure and melt flow behavior of a starch-based polymer. Rheol Acta 33 307-316... 

Thermal processing of starch-based polymers involves multiple chemical and physical reactions, e.g. water diffusion, granule expansion, gelatinization, decomposition, melting and crystallization [8]. Among the various phase... 

The future market success depends decisively on the polymers performance where e.g. Cerenol is superior to PLA and starch-based polymers concerning the strength versus stiffness index (Figure 12.8). 

Starch-based polymers Novamont (MaterBi) Films, molding. 

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