Starch water plasticized

Gaspar M., Benko Zs. Dogossy G. Reczey K., Czigany T. Reducing water absorption in compostable starch-based plastics. Polymer Degradation and Stability 90 563-569... 

A different approach was used by the Ferruzy Company, the main difference being the use of high boiling-point plasticizer instead of water for the destructuration of starch. In this technology, starch was plasticized together with polymers such as polyethylene-vinyl alcohol (EVOH), EAA, poly-e-caprolactone, with small amounts of moisture, in a twin-screw extruder [49], to produce an intimate mixture between starch and the synthetic polymer. The commercial trade name of this product family is Mater-Bi . 

C. Bastioli, R.Lombi, G.Deltredid and I.Guanella, De-structuring starch for use in biodegradable plastics articles - by heating non-dried, non-water-added starch with plasticizer and enzyme in an extruder, Eur. Pat. EP400531-A1, assigned to Novamont spa, 1991. 

If starch is modified by partially fermenting it, or esterifying or etherification, the resulting material can be extruded by adding plasticizers. Starch-based plastics are readily biodegraded. In most cases, the polymers are also water-soluble. Several suppliers now offer thermoplastic starch. Major markets include soluble films for industrial packaging, films for bags and sacks, and loose fill. 

Several companies have developed starch-based plastics. By using carefully selected starch feedstocks, and water as a plasticizer, they produce thermoplastics from nearly 100% starch, or from blends of starch with other biodegradable components. Many of these materials are water-soluble in addition to being biodegradable. The major target application has been as a replacement for polystyrene foam, including both molded cushions and loosefill. 

Starch-Based Plastics. As can be seen in Table 8.7, a variety of starch-based plastics have been produced by several companies. Starch-based plastics are often water-soluble as well as biodegradable. Some contain almost entirely starch others contain blends of starch with other biodegradable components. 

Due to the brittleness of starch materials, plasticizers are commonly used. A frequently utilized low weight hydroxyl compoxmd is glycerol. Another effective plasticizer is water, although not the best because it evaporates easily. Still, starch-based materials readily absorb water and this may result in significant changes in the mechanical properties. Different routes have been explored in order to improve the mechanical properties and water resistance of starch materials. These are chemical modifications to the starch molecule, blends with polymers such as polycaprolactone [61], or reinforcement with different types of cellulose-based fillers, such as ramie crystaUites [62], and timicin whiskers [63], or montmorillonite clay particles [64]. 

H.A. Pushpadass, A. Kumar, D.S. Jackson, R.L. Wehling, J.J. Dumais, and M.A. Hanna, Macromolecular changes in extruded starch-films plasticized with glycerol, water and stearic acid. Starch-Stdrke 61, 256-266 (2009). 

This led some environmental groups, such as the Environmental Defense Fund (EDF) and the Environmental Action Foundation (EAF), to call for a consumer boycott of degradable plastics. In contrast to these materials, starch-based plastics have been developed which are truly biodegradable. Some contain nearly 100% starch, and others are blends of starch with other biodegradable components. Most use carefully controlled amounts of water as a plasticizer to convert the starch into a thermoplastic, along with careftilly controlled temperature and pressure. 

Research on starch-based plastics has taken place in many coim-tries around the world. The Australian government funded a 1995 research project on development of starch-based plastics from corn and wheat, using water and glycerine as a plasticizer. In Japan, the Biodegradable Plastics Society was formed in 1989, with 48 member companies located mainly in Japan. By 1990, the membership had expanded to 69 companies, and included a significant number of non-Japanese members. In 1992, the U.S. Bio/Environmentally Degradable Polymer Society was formed, and had over 200 members by 1998.2 2... 

The mechanical properties of starch-based plastics of native com, potato, waxy com arrd wheat starch, produced by compression moitlding of native starch and glycerol in the weight ratio 0 to 3 were strongly dependent on the water content and starch sotrrce [38]. 

Bread is made from water plasticized wheat flour, which in turn consists of ground-up wheat seeds. Dry flour consists of approximately 12% of protein, 87% of starch, and approximately 1% of everything else, such as minerals and salts. Since both the protein and the starch are polymeric, bread dough and... 

Zuraida A, Yusliza Y, Anuar H, Mohd Khairul Muhaimin R (2012) The effect of water and citric acid on sago starch bio-plastics. Int Food Res J 19(2) 715-719... 

---