Bioplastics

 Bioplastics are polymers in which either the monomers are biobased and the plastic item is biodegradable at the end of its life, or possess both features.

 Biobased means the feed stock to produce monomers is derived from renewable biomass such as corn, sugarcane juice, bagasse, proteins from wheat, soya, agricultural wastes like straw, wood chips etc., instead of fossil fuels as in petrobased plastic.

 Biodegradation is a process in which the original material completely disappears within about 180 days due to the action of microorganisms present in the environment like soil, which convert materials into natural substances like carbon dioxide, water and produce humus, which can be used as fertiliser. 

There are two major types of bioplastics: 

1) those that are naturally produced by microorganisms and plants 

2) those that are synthesised by using biomass as feed stock

Biopolymers are  present in all living organisms in the form of nucleic acids, proteins, cellulose, etc.

 Cellulose consisting of a particular type of glucose called monosaccharides as the monomer is an important part of cell wall in all plants, many forms of algae and oomycetes. 

Because the monomers are bound tightly to each other to form cellulose, like plastics it also resists degradation. 

This is because, through millions of years of evolution microorganisms such as bacteria and fungi have evolved to biodegrade cellulose. They secrete enzymes called cellulases that break down cellulose to its monomers and use them as carbon and energy sources for their growth. 

Similarly grass eating animals like cows harbour certain types of bacteria such as Cellulomonas in their intestines to digest grass.

PHAs: (Polyhydroxyalkanoates):

PHAs (Polyhydroxyalkanoates or PHAs are polyesters produced in nature by microorganisms, including through bacterial fermentation of sugars or lipids) with a wide range of physical properties based on the composition of the monomers, how they are linked to form the polymer, and the length of the polymer chain (short, medium, and long). 

There are about 150 PHAs are there .

This makes them a versatile replacement for petro-plastics in a variety of applications, particularly single-use items such as bags, water and soda bottles, diapers, agricultural applications such as encapsulation of seed and fertilisers for controlled release. 

What are the objectives of developing bioplastics ?

Ans:The main objectives for the development of bioplastics are:

 • Conserve the fast-depleting fossil fuels 

• Reduce the carbon footprint-emission of greenhouse gases due to the production of plastics 

• Reduce environmental pollution due to the nonbiodegradability of the petro-based plastics