As the saying goes, reducing our environmental footprint should be as simple as practicing ‘reduce, reuse and recycle.’ Unfortunately, this mantra alone does not ensure sustainability or a pollution-free environment. Non-biodegradable polymers such as polystyrene and polyethylene, for instance, end up being the worst polluters, devastating fragile ecosystems.
Praveen Thoniyot, Senior Scientist and Team Leader at A*STAR’s Institute of Chemical and Engineering Sciences (ICES), believes that it is not only important to identify greener polymer alternatives, but also map their life cycles from synthesis to disposal. According to Thoniyot, such a sentiment is shared by key players in the plastic manufacturing industry.
“Studying the sustainability of polymer synthesis is gaining momentum due to the increased customer awareness, regulatory pressure on industry and opportunities to reduce costs,” explained Thoniyot. “There is [also] a lack of understanding of the environmental footprint of polymer syntheses.”
To demonstrate the feasibility of a laboratory-scale life cycle assessment (LCA), the team explored the synthesis of a promising biodegradable plastic called poly(ε-caprolactone), or PCL. Upon the recommendation of co-investigator Hsien Hui Khoo, Scientist and LCA expert at ICES, the team conducted the study using ISO 14040 and 14044 standards, an established framework for quantifying the overall sustainability of manufacturing practices.
According to first author Pancy Ang, Senior Research Engineer at ICES, laboratory-scale LCA is conducted using a cradle-to-gate system boundary, which starts with the extraction of raw materials and ends with the production of PCL homopolymer.
The researchers’ analyses allowed them to rank the three processes in terms of overall sustainability. “The hydrochloric acid-catalyzed ring-opening polymerization of ε-CL is the most environmentally sustainable route since it has the lowest environmental impact,” said Thoniyot. In contrast, the other two processes fell short on their sustainability checklist, either requiring large amounts of power or using chemicals toxic to humans.
These findings open up possibilities for future collaborations between academia and the green plastic manufacturing industry. “Laboratory-scale LCA could serve as a preliminary tool to evaluate the environmental sustainability of different technologies across domains before scaling up or commercialization,” added Thoniyot.
Taken altogether, this approach could become very useful in evaluating emerging biodegradable alternatives to phase out the current plastic materials that pollute and persist in the environment. Moving forward, the researchers plan to expand their analyses to paint a more holistic picture of the sustainability of different PCL synthesis technologies.
“In future projects, we wish to consider both the quantitative and qualitative aspects of synthesis,” concluded Thoniyot. “To our knowledge, there is no current research done on the laboratory-scale LCA comparison of existing and emerging [synthesis] technologies.”
The A*STAR researchers contributing to this work are from the Institute of Chemical and Engineering Sciences (ICES).