Bio polymers Biopolymers also called renewable polymers. Some biopolymers- such as (PLA), naturally occurring zein, and poly-3-hydroxybutyrate can be used as plastics, replacing the need for polystyrene or polyethylene based plastics.
Some plastics are now referred to as being ‘degradable’, ‘oxy-degradable’ or ‘UV-degradable’. This means that they break down when exposed to light or air, but these plastics are still primarily (as much as 98 per cent) oil-based and are not currently certified as ‘biodegradable’ under the European Union directive on Packaging and Packaging Waste. Biopolymers will break down, and some are suitable for domestic composting.
Biopolymers are produced from biomass for use in the packaging industry. Biomass comes from crops such as sugar beet, potatoes or wheat, when used to produce biopolymers, these are classified as non food crops. These can be converted in the following pathways:
Sugar beet > Glyconic acid > Polyglyconic acid
Starch > (fermentation) > Lactic acid > Polylactic acid (PLA)
Biomass > (fermentation) > Bioethanol > Ethene > Polyethylene
Many types of packaging can be made from biopolymers – food trays, blown starch pellets for shipping fragile goods, thin films for wrapping.
Impacts on Environment:
Biopolymers can be sustainable, carbon neutral and are always renewable, because they are made from plant materials which can be grown indefinitely. These plant materials come from agricultural non food crops. Therefore, the use of biopolymers would create a sustainable industry. In contrast, the feedstocks for polymers derived from petrochemicals will eventually deplete. In addition, biopolymers have the potential to cut carbon emissions and reduce CO2 quantities in the atmosphere: this is because the CO2released when they degrade can be reabsorbed by crops grown to replace them: this makes them close to carbon neutral.
Biodegradable and Compostable Biopolymers
Biopolymers are biodegradable, and some are also compostable. Some biopolymers are biodegradable. They are broken down into CO2 and water by microorganisms. Some of these biodegradable biopolymers are compostable. They can be put into an industrial composting process and will break down by 90% within six months. Biopolymers that do this can be marked with a ‘compostable’ symbol, under European Standard EN 13432 (2000). Packaging marked with this symbol can be put into industrial composting processes and will break down within six months or less. An example of a compostable polymer is PLA film under 20μm thickness, films which are thicker than that do not qualify as compostable, even though they are biodegradable. In Europe there is a home composting standard and associated logo that enables consumers to identify and dispose of packaging in their compost heap.