IFM researchers are investigating the use of novel materials to develop sustainable, biodegradable coffee cups and pods.

The volume of single-use plastic packaging is increasing exponentially, putting unsustainable pressure on plastic resources and waste disposal systems.

In Australia alone, close to one billion disposable coffee cups are used each year and discarded in landfill or improperly disposed of in recycling containers, causing further contamination in the cardboard and paper recycling stream (2016 figures).

Most disposable coffee cups currently on the market are not recyclable or biodegradable due to the polymer lining which insulates the cardboard outer layer from the hot beverage.

While some recyclable or biodegradable solutions are emerging, IFM is hoping to develop more sustainable and scalable solutions based on bio-sourced and biodegradable coating materials which can be composted directly after use.

In the first stage to develop a fully biodegradable, disposable coffee cup, Dr Ludovic Dumee and colleagues investigated the properties and potential of two novel biopolymer-based insulating liners.

The study aimed to develop a coffee cup material comprised only of biodegradable materials. PVA and chitosan proved to be good candidates as substitutes for fossil-fuel derived polymers such as polyethylene, which are used in commercial disposable coffee cups. Both biopolymers were cross-linked in order to provide better adhesion with the cardboard support and improve their liquid barrier properties. This cross-linking increased the durability of the biocomposite when exposed to water and hot coffee.

The coating method can be easily scaled up to offer new environmentally friendly options for manufacturers of takeaway cups.

Coffee pods

The researchers are now conducting the second stage of the project, looking at developing the materials further, the coating procedure and shaping the biocomposite into a coffee cup form. They are also taking the concept to the next level by tackling the issue of non-recyclable coffee pods used in single pod coffee machines.

Disposable coffee pods represent a great environmental and recycling challenge since they are either composed of aluminum (Nespresso system) or poly(ethylene) (Cafitally, Aldi…) materials. Although aluminum may be ultimately recycled, the process involves extensive washing and crushing of the metal pods, prior to reprocessing, which renders the process environmentally unfriendly and expensive.

The poly(ethylene) pods are non-recyclable and their disposal in landfill causes issues related to bio-contamination and uncontrolled long-term development of germs and pathogens as the brewed coffee grinds take a long time to degrade.

In a properly designed and engineered system however, this waste coffee could generate bio-compost materials which may be directly used to promote plant growth.

Dr Dumee and colleagues are designing advanced coatings and plastic parts made from low cost bio-sourced and bio-degradable polymers. The properties of the polymers will be tuned by controlling the degree of polymerization finely, to ensure similar performance as that offered by otherwise non-degradable plastic materials.

They propose to use waste materials from agriculture and food processing industries to generate the desired biopolymers. The strategy will therefore add value to waste products and lead to the design of fully degradable and reusable materials. They will then test and develop these bio-sourced and bio-degradable materials to mold and form coffee pods in a single step using advanced 3D printing technologies. The pods will then be entirely bio-degradable and could be used as compost material or nutrients for agricultural applications. Several companies have already expressed interest in this work.