Biodegradable plastics

BIODEGRADABLE PLASTICS, METHOD OF PREPARATION, PLASTIC WASET,

1. BIODEGRADABLE PLASTICS PRESENTED BY-: VIBHA SINHA MSC. IIIrd sem PLANT BIOTECHNOLOGY

2. PLASTICS- A synthetic material made from a wide range of organic polymers such as polyethylene, PVC, nylon, etc., that can be moulded into shape while soft, and then set into a rigid or slightly elastic form. Now a days plastics are major pollutants .

3. BIOPLASTIC Biodegradable plastics is plastic that decompose naturally in the environment. This is achieved when microorganism in the environment metabolize and breakdown the structure of biodegradable plastics . The end result is one which is less harmful to the environment then traditional plastics   A polymer derived from natural sources, e.g corn or sugars.

4. HISTORY Plastic was first invented in 1862 1862: The first ever man made plastic was a bio-plastic. It was made from cellulose nitrate and wascalles Parkesine. 1924: Henry Ford uses food stock to create a bio-plastic for car construction 1941: Henry Ford unveils the first bio-plastic car 1970’s: people demanded that research should be done on creating a non oil based plastic because of the oil crisis 1990: A British Company called Imperial Chemical Industries developed a bioplastic, Biopol, that was biodegradable.

5. EXAMPLES OF BIODEGRADABLE PLASTICS Polyhydroxybutyrate PHB is a poly(hydroxyalkanoate) (PHA), a biodegradable plastic produced by microorganisms first discovered by Lemoigne in 1925. Later, it was found that several other bacterial strains could also produce PHB. Chemical synthesis has also been found by Shelton  et al . Among all, polyhydroxybutyrate (PHB) is the most common polymer . a linear polyester of d(−)-3-hydroxybutyric acid . In general, PHB is a semicrystalline surface-eroding polymer which undergoes hydrolytic cleavage of the ester bonds . L- and D-lactic acid Many microorganisms produce lactic acid,  Lactobacillus  strains are particularly useful due to their high acid tolerance and relative ease of genetic manipulation. However, lactic acid bacteria also have undesirable traits. They are fastidious in terms of nutrient requirements, which often complicates product recovery, and additionally, incomplete or negligible pentose utilization excludes the use of xylose, the second most abundant sugar in nature, in fermentation processes . Polystyrene to PHA The conversion of PS to PHA was the first reported technology for the recycling of waste plastics to a biodegradable plastic (PHA) (Ward et al., 2006). This process involved the pyrolysis of PS to styrene oil, followed by the bacterial conversion of the styrene oil to PHA by  Pseudomonas putida  CA-3 (Ward et al., 2006). The pyrolysis (520 °C) of PS in a fluidized bed-reactor (Quartz sand (0.3–0.5 mm)) resulted in the generation of an oil composed of styrene (82.8%, w/w) and low levels of other aromatic compounds.

6. MECHANISM Take some corn kernels. Process and mill them to extract the dextrose (a type of sugar) from their starch. Use fermenting vats to turn the dextrose into lactic acid. In a chemical plant, convert the lactic acid into lactide. Polymerize the lactide to make long-chain molecules of polylactide acid (PLA). Biodegradable plastics

7. TYPES OF BIODEGRADABLE PLASTICS Bio Based Plastics   These are bio or starch based plastics that are made from soy, corn, or potatoes , breaking down 60 percent or more, within 180 days or less. In order to do this, bio-based plastics need water, heat, and aeration. Bio-based plastics can take longer to decompose in landfills because of non-availability of aeration. The bio based plastics are non-recyclable. An example of bio-based plastic is the cellulose fiber plastic, which is made from reconstituted cellulose, and zein plastic, which is made from corn protein. Thermal Plastic Thermal biodegradable plastic has an additive that causes it to break down when exposed to high temperatures. This plastic is safe to use for foods because it is non-toxic, and it can often be recycled. These plastics come with an expiry date and may start to degrade if stored in hot temperature. They also start to degrade in hot places like the trash bags and landfill.

8. Oxo-Biodegradable Plastic This type of plastics needs oxygen in order to breakdown. Oxo-biodegradable plastic is less expensive to produce because it is easy to make with machinery that currently manufactures conventional plastics. When aerated it gradually breaks down into biodegradable fragments over a course of several months to a few years . e.g bottles , carryout bags Hydro-Biodegradable  These plastics break down when exposed to humidity at a faster rate than oxo-biodegradable plastic. When combined with moisture, they expand the plastic's molecular structure and allow the bioactive compounds to metabolize and neutralize the plastic.  Microbial Biodegradation Biodegradation of plastics can be achieved by enabling microorganisms in the environment to metabolize the molecular structure of plastic films to produce an inert humus-like material that is less harmful to the environment. The use of bioactive compounds, compounded with swelling agents, ensures that the plastic degrades first into humus, and then into carbon dioxide or methane and water, when buried. This requires no aeration and needs nine to 19 months to break down.

9. ADVANTAGE AND DISADVANTAGE OF BIOPLASTICS ADVANTAGE Carbon emission reduction Consumes less energy Less landfill area needed Recyclable DISADVANTAGE Need for composter Engineering issues Risk of contamination

10. APPLICATION DISPOSABLE ITEMS Packaging Crockery ,cutlery Pots ,bowls , straw Used for bags, trays fruit and vegetable containers Egg cartons , meat packaging Bottes for soft drink and dairy product NON DISPOSABLE ITEMS Mobile phone casing Carpet fibres Insulation car interiors Plastic piping Etc……

11. THANK-YOU 