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Research into biodegradable polymers helps fight plastic pollution

02 September 2024 | Story André Damons | Photo Supplied

Dr Puseletso Mofokeng — Dr Julia Puseletso Mofokeng, from the UFS’s Department of Chemistry, is doing research into biodegradable polymers for application in disposable product packaging.

A researcher from the University of the Free State (UFS) is contributing to the fight against plastic pollution through her research into biodegradable polymers – large, chain-like molecules – as a more environmentally friendly alternative to petroleum-based plastics.

Plastic pollution is a global environmental problem, with 19 to 23 million tonnes of plastic waste leaked into aquatic ecosystems every year.

Dr Julia Puseletso Mofokeng, Senior Lecturer and Researcher in the UFS Department of Chemistry, hopes her research into how biodegradable polymers can be used in disposable product packaging can influence the industry and policymakers to enforce the use of biopolymers or biodegradable polymers in disposable products. This would help reduce plastic waste and boost environment-conservation efforts.

The United Nations Environment Programme (UNEP) describes plastic waste as a serious environmental problem – humans produce about 400 million tonnes of plastic waste every year. Approximately 36% of all plastics produced are used in packaging, including single-use plastic products for food and beverage containers, approximately 85% of which ends up in landfills or as unregulated waste.

Researching biodegradable polymers

Dr Mofokeng’s desire to solve the waste problem in her community of Bophelong village in Qwaqwa, Free State – where community members dumped and burned all sorts of waste, including plastics – inspired her towards her field of research.

Today, her research is aimed at managing plastic waste to combat environmental and atmospheric pollution (from incineration), conserve energy, and improve water quality, including ensuring safe drinking water.

High levels of plastic waste have led to increased research into and development of biodegradable polymers as an alternative to non-biodegradable materials for short-shelf-life goods (such as packaging for fresh fruit and vegetables).

Biopolymers or biodegradable polymers, explains Dr Mofokeng, are derived from renewable resources including, but not limited to, vegetable oils, starches and animal fats. They can therefore be easily disposed of after use without harming the environment.

“My research is based on the preparation and characterisation of completely biodegradable polymers, their blends, and composites or nanocomposites filled with unmodified or modified inorganic fillers, natural fibres, as well as synthesised carbonaceous materials,” she says.

Such materials are developed for various applications, including packaging, electromagnetic interference shielding (blocking unwanted signals), and the removal of heavy metals and other contaminants from water bodies.

“To achieve these aims, I and my small research group are preparing completely biodegradable polymer blends.”

This involves adjusting their morphology (structure) and some of their properties (thermal, thermomechanical, mechanical, and flame retardancy) to match those of petroleum-based polymers in their replacement for disposable products; by reinforcing with natural fibres, and minerals.

Biodegradable polymers can degrade within a few days to a few years depending on their source, type, and biodegradation method used, while petroleum-based polymers can exist for hundreds to thousands of years without degrading. Moreover, because biodegradable polymers are produced from natural resources, their biodegradation mainly produces carbon dioxide, water, and other non-toxic byproducts, Dr Mofokeng adds.

“Biodegradable polymers can degrade by themselves under natural environmental conditions – in one to three years – or may require human intervention to degrade where composts are prepared or conditions are controlled in order to degrade the polymers. The latter two being the fastest, where it could take days to months. In my previous research project [we] kept polylactic acid filled with short sisal fibre in plain water at 80℃, and all the tested samples degraded within 10 days.”

She and a PhD student are conducting an ongoing experiment involving three different biodegradable polymer systems exposed to different conditions outside and under soil, measuring the rate of biodegradation by mimicking the environmental conditions found in dumping sites and landfills.

Signs of biodegradation on the samples showed clearly after 14 months, with cracks, surface erosion, and a decrease in the initial weighed mass, suggesting that the polymers could be completely degraded within two to three years.

Closer to goal

Dr Mofokeng, who has been a National Research Foundation (NRF) Y2-rated researcher since 2021, says since most food outlets and restaurants in South Africa have already started using paper- and bio-based polymer materials in cutlery, straws, and takeaway packaging, the country seems to be closer to its goal of using biodegradable polymers for disposable packaging.

The UFS, too, is aiming to phase out the use of plastic bottles in the next three to five years. This will be done by installing filtered water machines in all its buildings.

“We are now left with policymakers to enforce strict laws governing production; and retail industries to use biopolymers or biodegradable polymers in disposable packaging materials,” she says.

New research

Dr Mofokeng and her group’s research is in line with the United Nations’ Sustainable Development Goals (SDGs), including ensuring good health and wellbeing (SDG3), providing clean water and sanitation (SDG6), forging sustainable cities and communities (SDG11), establishing sustainable consumption and production patterns (SDG12), and protecting life below water (SDG14).

She has been researching polymers for almost two decades, and remains passionate about her research field and educating communities. Her new research project, in collaboration with colleagues from her department, targets the removal of heavy metals and other contaminants from groundwater. Testing and water treatment is set to take place in different regions in Qwaqwa, specifically among households that collect drinking and cooking water from boreholes.

Dr Mofokeng’s research group was established in 2016 with one honours and two master’s students. She has since supervised nine honours, seven master’s and one PhD student.

She also recently established international research collaborations with the Libyan Advanced Center for Chemical Analysis and the Faculty of Technology at the University of Banja Luka in Serbia.

News Archive

Inaugural lecture: Prof. Phillipe Burger

2007-11-26

Attending the lecture were, from the left: Prof. Tienie Crous (Dean of the Faculty of Economic and Management Sciences at the UFS), Prof. Phillipe Burger (Departmental Chairperson of the Department of Economics at the UFS), and Prof. Frederick Fourie (Rector and Vice-Chancellor of the UFS).
Photo: Stephen Collet

A summary of an inaugural lecture presented by Prof. Phillipe Burger on the topic: “The ups and downs of the South African Economy: Rough seas or smooth sailing?”

South African business cycle shows reduction in volatility

Better monetary policy and improvements in the financial sector that place less liquidity constraints on individuals is one of the main reasons for the reduction in the volatility of the South African economy. The improvement in access to the financial sector also enables individuals to manage their debt better.

These are some of the findings in an analysis on the volatility of the South African business cycle done by Prof. Philippe Burger, Departmental Chairperson of the University of the Free State’s (UFS) Department of Economics.

Prof. Burger delivered his inaugural lecture last night (22 November 2007) on the Main Campus in Bloemfontein on the topic “The ups and downs of the South African Economy: Rough seas or smooth sailing?”

In his lecture, Prof. Burger emphasised a few key aspects of the South African business cycle and indicated how it changed during the periods 1960-1976, 1976-1994 en 1994-2006.

With the Gross Domestic Product (GDP) as an indicator of the business cycle, the analysis identified the variables that showed the highest correlation with the GDP. During the periods 1976-1994 and 1994-2006, these included durable consumption, manufacturing investment, private sector investment, as well as investment in machinery and non-residential buildings. Other variables that also show a high correlation with the GDP are imports, non-durable consumption, investment in the financial services sector, investment by general government, as well as investment in residential buildings.

Prof. Burger’s analysis also shows that changes in durable consumption, investment in the manufacturing sector, investment in the private sector, as well as investment in non-residential buildings preceded changes in the GDP. If changes in a variable such as durable consumption precede changes in the GDP, it is an indication that durable consumption is one of the drivers of the business cycle. The up or down swing of durable consumption may, in other words, just as well contribute to an up or down swing in the business cycle.

A surprising finding of the analysis is the particularly strong role durable consumption has played in the business cycle since 1994. This finding is especially surprising due to the fact that durable consumption only constitutes about 12% of the total household consumption.

A further surprising finding is the particularly small role exports have been playing since 1960 as a driver of the business cycle. In South Africa it is still generally accepted that exports are one of the most important drivers of the business cycle. It is generally accepted that, should the business cycles of South Africa’s most important trade partners show an upward phase; these partners will purchase more from South Africa. This increase in exports will contribute to the South African economy moving upward. Prof. Burger’s analyses shows, however, that exports have generally never fulfil this role.

Over and above the identification of the drivers of the South African business cycle, Prof. Burger’s analysis also investigated the volatility of the business cycle.

When the periods 1976-1994 and 1994-2006 are compared, the analysis shows that the volatility of the business cycle has reduced since 1994 with more than half. The reduction in volatility can be traced to the reduction in the volatility of household consumption (especially durables and services), as well as a reduction in the volatility of investment in machinery, non-residential buildings and transport equipment. The last three coincide with the general reduction in the volatility of investment in the manufacturing sector. Investment in sectors such as electricity and transport (not to be confused with investment in transport equipment by various sectors) which are strongly dominated by the government, did not contribute to the decrease in volatility.

In his analysis, Prof. Burger supplies reasons for the reduction in volatility. One of the explanations is the reduction in the shocks affecting the economy – especially in the South African context. Another explanation is the application of an improved monetary policy by the South African Reserve Bank since the mid 1990’s. A third explanation is the better access to liquidity and credit since the mid 1990’s, which enables the better management of household finance and the absorption of financial shocks.

A further reason which contributed to the reduction in volatility in countries such as the United States of America’s business cycle is better inventory management. While the volatility of inventory in South Africa has also reduced there is, according to Prof. Burger, little proof that better inventory management contributed to the reduction in volatility of the GDP.

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