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Swinburne University of Technology Sarawak Campus

Research into new bioplastic bags shows promise

May 27, 2015

By Akshay Kakar

Plastics bags may seem rather handy for carrying our groceries or when used as a bag for throwing away garbage. However, once these bags are disposed they begin to create a lot of trouble for our environment, so much so that they have become an alarming concern for our planet.

According to National Geographic, eight million tons were dumped into the ocean in 2010 alone, and it predicts that this will increase 10-fold by 2020. Since most of this trash comes from the Asian region we also hold the key to solving this problem before it turns into a disaster.

Some countries have recognized the severity of this issue and have either imposed tax on the use of plastic bags or banned its usage altogether. Other governments have started to limit their use to specific days of the week so that those who utilise them on other days will be charged a fee. These steps have proven to be effective, and have drastically reduced the consumption of plastic bags.

However, this has not stopped our oceans from continually being dumped with plastic. So, is this really the solution? In my opinion, it is not morally right to pollute the ocean and suffocate marine life merely because plastic bags are convenient for our way of life. However, it does not mean that we have to completely stop using plastic bags.

Undoubtedly, in some situations plastic bags are more pragmatic, for example when carrying frozen food or liquid. It would be impractical and a nuisance to use paper bags for such purposes. And, paper bags are in fact not as green as they might seem. The production of plastic bags actually uses about 70% less energy and 96% less water than that required to manufacture recycled paper bags. So, recycling paper actually contributes a lot more towards global warming than recycling plastics does. Furthermore, plastic bags are thinner and more compact. For example, to transport a given quantity of plastic bags it takes only one truck but to move the same quantity of paper bags, seven trucks are required.  

Does this mean then that we now have to go back to taking along our woven bags with us each time we go shopping? Well, not really. Fortunately, material science has given us biodegradable plastics. Polylactic acid (PLA) is a bioplastic that is made from corn or potato starch. Producing PLA consumes less energy than the conventional non-degradable petroleum-based plastics. PLA tends to decompose in about six to 24 months depending on the environment in which it is disposed. The decomposition process can be sped up by spraying an alkaline solution onto the bags. Alternatively, PLA can be converted very efficiently into lactic acid, also known as “milk acid”, which is a naturally occurring chemical and is therefore biodegradable.

To make the new generation bioplastic bags more compatible with the environment, natural fibre composite materials can be used. Composite is a material made by mixing two different materials with distinctive properties. In this case, PLA could be combined with natural fibres such as those from luffa which is commonly available in Malaysia. Luffa is used as a shower scrub, and since it is cheap, light, strong, and grows naturally, it would make a good filler material for a luffa-PLA bio-composite.

Recent research at Swinburne Sarawak (http://goo.gl/Sp3Cea) has shown that a biocomposite with 15% luffa and 85% PLA retains about 86% of the strength of pure PLA. This means that we can now use luffa and further reduce the PLA component by 15%. This implies that the new age bioplastic will decompose faster, because less is used, while the fibres will act as manure for the soil.    

Replacing regular plastic and paper bags with the new biodegradable plastic bags has several advantages for us as well as for the environment: we no longer need to worry about leaving our woven shopping bags at home; we can still carry frozen products or liquid without making a mess; reuse the bioplastic bags for throwing out trash; and disposing the bioplastic bags along with other biodegradable materials. At the same time, it will contribute towards a better environment since the bags will decompose before the landfills are overfilled, or choke all life in the oceans. And, it will help to save precious water that would otherwise be used to recycle paper.   

In addition to bioplastic bags, the luffa–PLA biocomposite can be used to make many other products that we take for granted and throw away after a single use such as party cups, plastic cutleries, take-away containers, smart-phone casing, toothpaste tube, toothbrush and pens.

If you are wondering about the price we have to pay for the advantages the biodegradable plastic bags offer, well, it would cost only between RM0.10 to RM0.90 per bag. Since we are already being charged for using plastic bags on certain days we might as well fork out for biodegradable ones because it will directly and significantly contribute towards protecting our environment.    

Akshay Kakar is pursuing a Master of Engineering at Swinburne University of Technology Sarawak Campus. His research looks into environmentally friendly and sustainable materials. Akshay is contactable at akakar@swinburne.edu.my