Source

[Priyankaa Pitcheshwar]

Hey ppl,

I've jus put the main points about Starch based Bioplastics...!

• Starch based plastics account for 80% of the bioplastics market.
• A number of companies are now producing starch-based plastics throughout theworld including Biotec GmbH (Germany), VTT Chemical Technology (Finland),EverCorn, Inc. (US), Novamont (Italy), EarthShell (US), AVEBE (US), RodenburgBioPolymers (Netherlands), StarchTech, Inc. (US), and Vegeplast (France). The mainplayer in Europe is Novamont, which owns 80 patents and related extensions.Rodenburg BioPolymers (Netherlands) has built a plant to transform potato wastesgenerated by the french fry industry for use in injection moulding.
• One of the largest thermoplastic starch producers is Novamont. Novamont’s biopolymer is sold under the name Mater-Bi. Mater-Bi has been on the market in one form or another for almost 20 years.
• Starch-based plastics are used in specific industrial applications, such as the composting bags and sacks, fast food serviceware cups, cutlery, plates, straws etc.), packaging (soluble foams for industrial packaging, film wrapping, laminated paper, food containers), agriculture (much film, nursery pots, plant labels), hygiene (diaper back sheet, cotton swabs).
• Although the principle source of starch-based biopolymers varies across countries depending on the main source of carbohydrate available, generally, the main sources are corn/maize, wheat and legumes (United States, Australia), and potatoes (Europe). Other sources being explored include cassava (Thailand, India), and tapioca (Japan).
• It is estimated that starch-based plastics can save between 0.8 and 3.2 tonnes of CO2 per tonne compared to 1 tonne of fossil fuel-derived plastic.
• Starch based BP are thermoplastics that are blended with plasticizers and additives like sorbitol and glycerin.
• Disadvantages of using pure starch for packaging purposes are both the brittleness and the fast retrogradation.
• This can be avoided by using a high viscosity internal lubricant that increase the mobility and therefore facilitate the movement of the chain molecules. This lubricant should be hydrophilic nd also possess a low vapour pressure to increase the shelf life of the starch plastic. If starches and polyoles are mixed and cooked a thermoplastic mass results that has properties alike synthetic plastics and, moreover, classic polymer processes like extrusion, film blowing and injection moulding can be used for shaping.
• The strength of this thermoplastic starch can be similar to the strength of polystyrene.
• A problem that still exists is the sensitivity of the material to ambient moisture, both at short terms during production as at long times during usage.These problems increase with increasing surface to volume ratio of the final product like, for instance, films.

Process of making Thermoplastic starch/Plasticised starch

This gives details of Starch extraction....

http://www.zuckerforschung.at/inhalt_en.php?titel=STARCH TECHNOLOGIE&nav=nstaerkeinfo_en&con=cigsmais_en

This link gives all the details of making thermoplastics starch....

http://www.biodeg.net/biomaterial.html

Starch presents many characteristics, found in synthetic polymers, in the one polymer: linear chains with a single repeat unit, branching, hydrogen bonding, crystallinity, gelatinisation,melting and glass transition phenomena, liquid crystalline characteristics, retrogradation,upper critical solution temperature behaviour, solubility, gelation all combined to form the technology of thermoplastic starch production.

PDF is basically abt starch sources cultivated in India. Cassava starch seems to be the most widely used in India fr making BP....!