Degradable
Plastics - Global & Domestic Scenario
Biodegradable
plastics that get microbially decomposed have attracted much attention
globally as they become a part of the natural ecosystem and thus cause
no eco problem.
Introduction
Plastics
due to their versatility have become essential ingredients to provide
a quality to life. Nearly 50% of plastics are consumed by the packaging
and construction industry. Other major consumption is by consumer
goods (16%), electrical (8%), automobile (7%) and agriculture (5%).
Per capita consumption of plastics has been steadily on the increase,
obviously leading to waste. They are both recoverable and non-recoverable.
The latter are more difficult to deal with and create environment
related problems. The desirable approach is to degrade them in the
natural environmental conditions and within a reasonable time frame.
Factors that affect biodegradation include physico chemical properties,
microbiological parameters, primary properties and material processing.
The degradation of plastics in the environment can undergo abiotic
or biotic degradation or remain as it is. Photo oxidation, hydrolysis,
oxidation and photolysis influence abiotic degradation, which is partial
and forms fragments. Biotic degradation is influenced by environmental
conditions and presence of microbes – type and quantum wise.
The degradation could be into smaller fragments or complete mineralisation
as molecules of methane, CO2, water, salt and biomass. Effective and
efficient biodegradation is effective through consortium of appropriate
micro-organisms, conducive environmental conditions that help microbial
growth and vulnerability of substrate for microbial attack. A review
of common test methods used for assessing biodegradability of plastics
materials are illustrated in table below. Most plastics do not decompose
in the environment and hence can be ignored. Therefore biodegradable
plastics that get microbially decomposed have attracted much attention
globally as they become a part of the natural ecosystem and thus cause
no eco problem. Biodegradable plastics are preferred more in single
use/one shot packaging systems. Biodegradable plastics should thus
be end use performance oriented and biodegrade conforming to appropriate
waste management infrastructure into environmentally compatible constituents
such as CO2, H2O and compost. Significantly, they leave no persistent
or toxic residue. The degradability is generally affected by the chemical
bonding, functional group, structural unit, microstructure, side chain,
molecular weight, melting point and crystallinity. Environmentally
degradable plastics find innumerable opportunities. They include fast
food, one way packaging and personal hygiene products, which are compostable
without separation. The other typical examples include mulchable agricultural
films and fishing gears. The prospective markets for biodegradable
polymer includes wraps for various consumer goods, viz., medicines,
agricultural, forestry and fishery products, blending stocks, plasticisers,
lubricants, pesticides, detergents and chemical agents for fibres
and papers. The optimal use of degradable polymers necessitates the
formulation of appropriate characteristics with degradation time as
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