Plastics may be either (a) photodegradable or (b) semi-biodegradable or (c) 100% biodegradable. Photodegradable plastics have light sensitive groups incorpora ted directly into backbone of the polymer as additives. This produces non-degradable smaller fragments which cause loss of material integrity. Example of semibiodegradable plastic can be blends of starch and polyethylene. PHB is an example of 100% biodegradable plastic. Approximately a dozen of inherently biodegradable plastics are now in the market, with range of properties suitable for various consumer products. Some examples of biodegradable films or other raw material (for biodegradable plastic articles) made by different companies are -

(1) BASF - Ecoflex - for biodegradable garbage bags - made up of polyester
building blocks that offer properties similar to LDPE (10000 tonnes production
plant at Ludwigshafen, Germany.
(2) Bayer - BAKbiodegradable polyester amide. - contains ester and amide groups
similar to that in nature.- therefore biodegradable.
(3) Dupont's - BioMax
(4) Eastman's - EasterBio
(5) Cargill-Dow's - EcoPla
All of them are targetting market of 70000 tonnes by 2001.
(6) Arrow Coated Products Ltd. (ACPL) has started bioplastic watr soluble film
production in India in Gujrat State at Ankleshwar. But capacity is only 600
tonnes per annum. They do not export any of it.
(7) Om Engineers (India) - have also tested and about to introduce LDPE
modified biodegradable film (for which they have applied for patent even.
(8) Fasalex, The Institute for AgroBiotechnology, Kopfig, Austria have developed biodegradable material using sawdust and corn grit held together with cellulose based natural resin. This material can be processed by same machines which are otherwise used for normal plastic.
(9) Environmental polymers of Warrington make biodegradable polymer which can be melt - processed by film blowing or injection moulding etc. Product is water soluble and is useful for interior purpose. It is based on PVOH.
Estimate of current global market for biodegradable plastic is 1.3 billion kg per year. Estimated global market for biodegradable polymers will reach 1.4 billion tons by the year 2000. In response to increasing public concern over environmental hazard caused by plastic, many countries are conducting various solid waste management programmes incl uding plastic waste reduction by development of biodegradable plastic material. There is an intense research for making the biodegradable plastic. Some biodegradable plastic materials under development are -

1. PHAs
2. Polylactides
3. Aliphatic polyesters
4. Polysaccharides
5. Co-polymers and/or blends of above.

Different approaches are -

• (I) modification of existing material,
• (II) chemical co-polymerisation of known biodegradable material,
• (III) use of biopolymers for making plastics.

(I) Partially biodegradable shopping bags are already manufactured from thin matrix of conventional polythene filled in with starch. After the bag has been thrown away, microorganisms eat away starch, leaving polythene film structure which soon disintegrates. Fertec (Ferruzzi, Ricercae Technologia) of Italy and Warner Lambert of the US are developing fully biodegradable starch-based plastics. Starch forms upto 50% by weight of the Fertec material and remaining is the synthetic polymer. Material shows partial biodegr adability in Warburg test. Warner Lambert's starch-based plastic is called Novon and contains 80% starch. Additives like plasticizers are used to make the material tougher and to improve processing. Novon is biodegradable in accelerated landfill, controlled compost, aerobic and anaerobic aquatic environments. Warner's starch-based plastic can be used for capsules for drugs, disposable single-use items like cups and food trays. The company has 25000 tonnes per annum production capacity from 1992. At present, biodegradable plastic represents just a tiny market compared with the conventional petrochemical material whose production amounts to >100 million tonnes per year. Bioplastics will comparatively prove cheaper when oil prices will continue to hike up.

(II) 'Bioceta' is the new biodegradable plastic which is cellulose diacetate-based product. It has been developed by Rhone Poulenc's Belgium subsidiary, Tubiz plastics. Bioceta uses additives which both plasticize and accelerate degradation by micro-organisms. The Sekisui chemical company has developed a new biodegradable plastic by co-polymerisation of two different biodegradable chemicals based on aliphatic polyester derivatives. The plastic has both good properties and complete biodegradability. The biodegradability and properties of new plastic can be adjusted to a larger extent by controlling the conditions of polymerization. It is thermoplastic and can be recycled. The plastic can be used effectively for agriculture, for goods packaging, but high-value add ed plastic can also be produced using the co-polymer. The plastic was developed in co-operation with the Government Industrial Research Institute, Osaka. Plastic is based on polyester which is decomposed by means of enzymes such as lipase to H₂O + CO₂ causing no secondary contamination as in other degradable plastics. According to firm s claim, this plastic is stronger than polyethylene, has a higher melting point (over 90⁰C) than the ordinary polyester resin and have fastest biodegradability. A film of 100 micron thickness of this plastic is totally decomposed in soil in just two months. Biodegradable plastic film comparable in strength to the general purpose polyethylene has been developed in Japan by the Agency of Industrial Science and Technology's (AIST) Fermentation Research Institute. The film has tensile strength of 200 kg/cm and is produced from a mixture of polycaprolactone (PCL) which is completely biodegradable and special compatible polyolefin. The mixture has a PCL content of 50-80% by weight a nd is formed with higher proportion of biodegradable PCL towards the surface, thus promoting high biodegradability while retaining the strength of special polyolefin. If buried in soil for a year, the film is degraded by micro-organisms into a powder with particles ranging from 1-10 microns. It releases no harmful gases when incinerated and has calorific value of 8000 k.cal per kg which is 80% of ordinary films. Co-polymers of succinic acid, glycerol and polyethylene glycol are found to be 100% biodegradable in 90 days in soil. They have glass transition temperature (Tg), 21}

(III) Bioplastics - Biopolymers obtained from growth of micro-organisms or from plants which are genetically-engineered to produce such polymers are likely to replace currently used plastics at least in some of the fields. Poly - hydroxy butyrate and polylactic acid are the kind of polymers which are used as materials of bioplastics.

This WebSite will concentrate on biopolymers the real Bioplastics - Biodegradable and of complete natural origin.

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