Opinion: The future of sustainable plastic

The use of plastic is vital in our everyday lives. Yet most plastic is based on non-renewable fossil-based resources, which is not a sustainable situation. How can plastics become sustainable?

One path that is being pursued every more intensively is that of recycling. By recycling resources, we contribute to the cycle of renewing plastic while maintaining biocapacity and reducing pollution and waste. Waste recycling on a larger scale aids in preventing the depletion of natural resources.

As consumers, we have a responsibility to effectively recycle the plastic waste we produce so that plastic can be returned to the industrial and economic cycle. The state of recycling today is dependent on infrastructure - and the payoff of recycling is going to give long-term benefits to the economy and environment as well as dictate the future sustainability of plastics.

Inexpensive, lightweight and durable, plastic is a highly utilized synthetic material in modern society. Currently, seven different types of plastics are commonly distinguished: PET, HDPE, PVC-U, LDPE, PP and ‘other’, referring to plastic that is mixed or layered.  Each type is composed of different organic compounds and features its own spectrum of physical and chemical properties. The recyclability and preprocessing of a plastic is dependent on its chemical composition.

Amidst a global pandemic, the use of plastic in personal protective equipment has significantly increased, as big oil firms are investing hundreds of billions of dollars to make new plastic. The cost of recycling and of recycled plastics has soared. As a result, the market for plastic shows that the higher prices for recycled plastic makes sustainable plastic a less favoured option amongst industries that rely on cheaper material to make profitable goods. The big question today is therefore: how to make plastic more sustainable without sacrificing the cost or quality?

Since 2012,  demand for sustainable products has been rising steadily due, mainly to growing consumer awareness People are concerned about how their waste is being reused and where it is going after being discarded as waste.
Producers have experimented with replacing glass and other fillers with plant fibres, wood, and starches to enhance the sustainability, renewability and recyclability of their products. Others have developed bio-based solutions that are compostable or biodegradable at the end of life. Although modern day technology does not allude to a singular solution to enabling plastic sustainability without compromising its integrity, those resources can replace petroleum-based feedstocks, bringing humanity one step closer to determining the innovation of modern-day biodegradable products, writes Joe Brock in the “The Plastic Pandemic” (Reuters Investigates, 05 Oct. 2020).

Sustainability in plastics can be therefore promoted at the beginning of life, through feedstock choice and at the end of life, by choosing options that promote circularity while preventing the depletion of non-renewable petroleum resources.

Current end of life options are: recycling, biodegradation, landfilling, and incineration. And the current the reality is that most of our waste directly goes to landfills which are limited in space and contribute to long-term pollution.

One promising technology that is currently emerging is chemical, or feedstock recycling, using a pyrolytic conversion process is used to convert scrap plastic to fuel sources. It is done by distillation where gas is converted to liquid form. Any acids that are corrosive to PTF systems are removed. The final step is refining the product  - by adding it to the cracker - so it can be further processed. This process has the advantage that multi-layered, hard-to-recycled plastics are able to be processed and returned to the plastic loop, thus answering the need for circularity by avoiding waste and the depletion of natural resources. Currently, however, the process is energy intensive and expensive. With upscaling, however, this situation will improve.

Biodegradation is hailed as another route to avoiding the buildup of waste in landfills. Using biodegradable plastics can reduce our carbon footprint, greenhouse gas emissions, and waste pollution. One of the materials we are examining is starch, and the use of starch-based bioplastics as a sustainable packaging material. Starch is an organic material made up of polysaccharides and is extracted from plant-based resources through a milling process and consists of two polymers: amylose, a linear polymer and amylopectin, a branched polymer. When plastics are combined with starch-based minerals, it provides the plastics with water-resistant properties. Starch films that are mixed with biodegradable components has been proven to be more efficient in reducing permeability

There are many challenges that researchers have to face before they can implement starch-based plastic as a norm. The first being the deterioration of high starch content which will break down into carbon dioxide and water within several months. This poses an issue with products that need to be preserved for long periods of time. Another issue that starch-based bioplastics poses is the risk of microbial growth in food. This would require even more capital to ensure that there are antimicrobial packaging measures put in place, in order to avoid any food-borne outbreaks. The future of sustainable bioplastics using starch-based biodegradable plastic is still in the works as there are many issues that will make its use challenging. At the same time, researchers need to develop a way for the products that use sustainable plastic packaging to hold the same quality and shelf-life, while also being cost efficient and environmentally friendly.

Conclusion

Although modern technology is still a long way from constituting a comprehensive solution to sustainable plastics, there are many things that we can do as consumers to maintain the integrity of the current biodegradable plastics. If the average consumer continues engaging in waste recycling and purchasing “greener” products, then we can collectively reduce our carbon footprint. For example, replacing petroleum-based plastics with renewable, reclaimed, or recycled materials will substantially reduce your carbon footprint. Similarly, using more compostable materials like wood and natural fibers offers the incentive for consumers to return these products back to their original state through composting.

About the authors

This article was written by Raj Shah, a director at Koehler Instrument Company,  a Fellow of the Royal Society of chemistry, an adjunct professor at State University of New York, Stony Brook, and an author of over 300 publications and Serline Cai, a chemical engineering student at Stony Brook University. Contact : [email protected]