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Plastics in the Environment†
By: M. M. Sharma, F.R.S.* & R.
A. Mashelkar, F.R.S**
Plastics have moulded the
modern world and transformed the quality of life. There is no human activity
where plastics do not play a key role, from clothing to shelter, from
transportation to communication and from entertainment to health care.
Plastics, because of its many attractive properties, such as lightweight,
high strength and ease of processing, meet a large share of the material
needs of man. From practically zero in the fifties, humankind today consumes
greater than one hundred and fifty million tons of plastics. We truly live
in a ‘Plastic Age’. Our daily lives would be very much poorer without these
benign and environmentally friendly materials. Plastics possess a unique
combination of properties. Plastics can be super tough, rigid as well as
flexible, transparent as well as opaque and can allow selective permeation
or act as a barrier material.
Nature has produced ‘plastic’ –
like materials for centuries. Silk and cellulose are example of natural
polymers. Reference to Shellac, a thermoplastic can be found even in
Mahabharatha!
Growing population and
consumption in India has put severe pressure on our natural resources and
fragile ecosystems. The material needs of our population are growing and
plastics offer a cost-effective alternative.
Plastics are employed in myriad
applications where they actually conserve natural resources. For example,
asceptic packaging of food in barrier packaging films will render
refrigeration unnecessary, saving capital and energy. Edible oils and milk
are packaged in flexible packages eliminating the use of tin and glass
containers. Rigid HDPE barrels are used for bulk chemical storage instead of
steel drums. Apart from conserving natural resources, use of plastics in
these applications saves transportation fuel as plastics are substantially
lighter than tin, glass or steel.
Safe drinking water packaged in
PET bottles are a very common sight now-a-days. They provide confidence to
consumer on the quality of water and help reduce waterborne diseases.
Advanced polymeric membranes help purify water from viruses and bacteria.
They also provide potable drinking water from sea and brackish water through
a process of desalination.
The fact that plastics are made
from hydrocarbons derived from petroleum, which is non-renewable, has raised
questions concerning its sustainability. Nevertheless, the consumption of
petroleum hydrocarbon for the production of plastics is less than 5%, the
balance being consumed as fuels
and energy source. Consequently, the concerns about sustainability of
plastic materials is somewhat exaggerated. On the contrary, processing of
many natural materials (glass, paper, wood, metals) consume far more energy
and thus lead to greater consumption of fossil fuels. Additionally, research
and development work currently in progress globally will provide future
opportunities to make some of the plastics from biomass and other renewable
resources. Thus, plastic manufacture will become even more sustainable in
the years to come. It is fair to say that plastics replace several natural
materials, which are either scarce, consume more energy for processing or
cause damage to the eco-systems during their production. Thus use of
plast5ics makes a positive contribution to the sustainability of earth’s
resources.
Another issue that is often
discussed is whether because of their non-biodegradability, plastics will
cause damage to our ecosystems. The signature of all natural materials made
by biological processes is that they are biodegradable and bio-assimilable.
The long life and desirability of plastics, which have made them a material
of choice for many applications is seemingly a disadvantage when it comes to
their disposal. However, when handled properly, plastics do little damage to
our environment.
Plastics have the advantage
that they can be easily reprocessed and recycled. In some cases, one can
recover even the raw materials that were originally used in their
manufacture. Plastics offer the unique advantage that one can recover the
fuel value contained in the hydrocarbon polymer after its use. Plastics can
also be made environmentally degradable, especially for packaging
applications. There are expectations that in the neat future plastics will
be made even biodegradable and compostable so that waste plastics can be3
handled the same way as wet food waste and agricultural waste. The overall
eco-friendliness of plastics becomes apparent when one evaluated the total
‘life cycle, namely, an analysis of raw materials, energy, effluents,
methods of disposal, etc., of a material from its origin to its final
disposal.
*Kothari
Research Professor, Jawaharlal Nehru Centre for Advanced Research; Former
Professor of Chemical Engineering Director UDCT, Mumbai
** Former Director General,
CSIR & Secretary, Department of Scientific Industrial Research (Govt. of
India)
†We
are grateful to Indian Centre for Plastics in the Environment, Mumbai for
permitting us to publish an edited version of the article, which was
recently published in the form of a message by Eco-Echoes. |
