Biopolymers that are cheaper to produce, heat-resistant, biocompatible and biodegradable are promising alternatives to plastics.
By Sanmitra Barman
It’s hard to imagine life without plastic.
It’s everywhere — from toothbrushes, to our cell phones and laptops.
In 2023, more than 300 million tonnes of plastics were produced worldwide from the by-products of the oil and gas industry. About 97 percent of these are non-biodegradable.
This is higher than the weight of the total global human population.
Every day, the world dumps 2,000 garbage trucks full of plastics into oceans, rivers and lakes, disrupting marine life and threatening human health.
If we don’t respond, stocks of accumulated plastics in the aquatic environment will more than triple from 140 million tonnes in 2019, to 493 million tonnes in 2060.
Over 90 percent of the commodities that use plastic are made from seven different varieties, of which only two can be recycled.
Others will end up in a landfill and take up to 500 years to degrade completely.
Although the complete degradation of plastic results in a green-house gas such as carbon-dioxide, the more pertinent danger comes from microplastics.
Microplastics are defined as plastic particles ranging in size from 5 millimeters, which is about the size of a pencil eraser, to 1 nanometer (nm). A strand of human hair, for instance, is about 80,000 nanometers wide.
These are likely to degrade into even smaller particles due to chemical weathering processes, mechanical breakdown, and digestive processes of animals.
Given their micro-level sizes, microplastics can move easily through the food chain and pose health hazards to humans and animals.
Research on cell cultures, marine wildlife, and animal models indicates microplastics can cause oxidative and DNA damage, as well as changes in gene activity, all of which are known risks for cancer.
World leaders are grappling with tackling the crisis of plastic pollution, and bans on single-use plastics or waste management regulations only mark the first steps towards addressing the issue.
There’s a strong case to be made for finding sustainable alternatives.
Environment-friendly alternatives and biopolymers
Plastics became indispensable because of low production costs, relatively easy and well-researched manufacturing processes, and availability of raw material from by-products of the oil and gas industry.
It is also lightweight, durable, has high strength-to-weight ratio, is thermally and electrically insulated, inexpensive and non-biodegradable.
Non-biodegradability, or when bacteria or other living organisms cannot decompose the material, pollutes the environment, but is a blessing for storing food and medicines.
Substitutes such as upcycled tyres, coconut, bamboo, jute and wheat straw exist, but given the disadvantages, can only be used selectively.
Bamboo is being used in low to medium strength commodities such as cutlery, tissues, stationery, serving trays and workout towels.
Bamboo tree farming is easier, faster and robust; the trees filter air and water, and fight pathogens too.
Such products are biodegradable and robust, but lack the advantages of plastics — lightweight with high strength-to-weight ratio, and moldable.
Jute has high tensile strength and is biodegradable too.
However, it is not moldable and water resistant.
In vehicles, plastic is the second most commonly used material after metals. It reduces the total weight of the vehicle, making it fuel efficient.
Automakers have been working to develop advanced technologies such as additive manufacturing, or 3D printing.
It helps automakers develop new components with complex designs and structures, which increase the efficiency of the components.
This technology also allows for the use of plastic alternatives — petrochemical based resins such as ABS (acrylonitrile butadiene styrene) for high strength and heat stability, nylon for flexibility, polycarbonates for high impact strength and polyether ether ketone for high mechanical strength.
But these polymers are non-biodegradable, and recycling them is a costly affair.
Several automobile companies have started using bio polymers — derived from natural sources such as food waste, cornstarch and castor oil. Such biopolymers are sustainable in terms of low carbon footprint.
Not all biopolymers — except polyhydroxyalkanoate, or PHA — are completely biodegradable under natural environmental conditions.
PHA is fast and cheap to manufacture, and has excellent biocompatibility and biodegradability.
Biodegradable plastic as an alternative to petroleum-based plastic is in huge demand for medical devices, drug-delivery systems and medical packaging.
This is because most of the petroleum-based plastics are non-biodegradable and can be toxic for humans.
However, even PHA has disadvantages such as low resistance to heat, fragility and is challenging to process.
In agriculture, the use of PHA-based mulch films — used to retain soil moisture and prevent weed growth — are quite popular due to the ease of biodegradability. These are replacements for synthetic plastic mulch films used in agriculture to control weeds, protect against diseases and improve crop quality.
The food packaging industry is also more inclined towards biodegradable and bio-based polymers such as PHA. Hence, PHA is the hope for a sustainable future in the plastic industry. It can be produced from organic waste including food, agriculture, dairy industry and fermented molasses.
Naturally occurring bacteria can convert organic waste into PHA in three to five days.
PHA has several useful derivatives too, such as polyhydroxybutyrates, or PHB, which can replace petroleum-based single-use plastic. PHB can be produced out of completely natural organic waste, making it an ideal candidate for a carbon neutral circular economy.
But production cost is an impediment — six times that of petroleum-based single-use plastics. Other drawbacks include low heat and water resistance, and low strength to weight ratio.
Automobile companies such as Toyota and Mazda have started using biobased polymers in their cars.
Global unity to end plastic pollution
Several start-ups, mostly based out of the UK and the US, are working on biodegradable polymers. These include Full Cycle, Genesis, Refork and OMAO. Governments in heavily industrialised western countries are also encouraging start-ups to find solutions to the plastic problem.
However, more research needs to be done on several fronts, particularly on lowering production costs.
International groups such as the intergovernmental negotiating committee on plastic pollution need to come up with policies for business to take place between nations sustainably.
The committee was convened after the UN environment assembly met in March 2022, and decided to develop an international legally binding agreement on plastic pollution, including in the marine environment.
The committee’s recent meeting in South Korea failed to finalise an agreement to end plastic pollution.
Earlier this year, at the meeting in Canada, one of the agenda items was to encourage the use of bio-based, biodegradable plastic.
Bioplastics can be either bio-based — fully or partially made from biomass — or biodegradable, or can be a combination of the two.
The benefits are immense.
They can reduce reliance on finite fossil resources, lower greenhouse gas emissions from plastic production and can decompose harmlessly.
But bioplastics currently account for only about 1 percent of the total global market share of plastics.
Awareness and facilities for proper waste management, tax incentives, and innovation to improve the cost and performance of bioplastics to match the economics and properties of conventional plastics, can help pave the way towards a sustainable, bioplastics future.
Dr. Sanmitra Barman is an associate professor of chemistry at the BML Munjal University in Haryana. He teaches courses such as environmental science and nanoscience. His areas of research are green hydrogen production by water splitting and sensing of environmental pollutants by Raman Spectroscopy.
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Originally published under Creative Commons by 360info™.