By Guest Author 12/07/2018


Lou Sherman

People say there is too much plastic packaging in today’s global marketplace. But packaging protects the product through the supply chain and prevents product waste.

Plastic is an attractive material to use for packaging as it is lightweight and has the right properties to enable products to survive long supply chains such as overseas exports. Many consumers do not understand this benefit and are frustrated that they are left to manage it once it becomes waste. There is also an increased awareness around plastic packaging waste causing havoc in our environment.

There is a need to improve waste management options to ensure plastic packaging is collected and processed appropriately before it leaks into the environment. This problem has been recognised on a global level by the Ellen McArthur Foundation and they have established an initiative to create a global plastics circular economy. Many multinational organisations agree with this approach and have signed up to a pact to make all their plastic packaging reusable, recyclable or compostable by 2025. In New Zealand, there is a similar agreement that has been established together with the Ministry for the Environment.

To establish a true circular economy, reusable and recyclable packaging should be prioritised. However, plastics are inherently more difficult to recycle than other packaging materials such as glass and metal. This is because not all plastic packing is made from the same polymer and often different additives such as colour are included. Plastic recycling also can be affected by product contamination – that the food and other products the packaging has contained can cause a contamination problem.

Compostable plastics are an attractive alternative. Especially if it also presents an opportunity to divert food waste from landfill. Already there are several compostable plastics available that can be used for packaging. Industrial composting facilities are normally designed to process organic waste a lot faster than your home compost and can generate higher temperatures for longer periods of time, which accelerates the degradation.

Generally 60°C is a critical temperature that needs to be reached in an industrial compost pile. Polylatic acid (PLA), in particular, needs this temperature in order to degrade within the time frame expected of a composting process. Some compostable plastics can break down in home composting environments; however, if they are too thick then they will not break down in a home compost in a reasonable timeframe.

In the market, there are a range of materials which claim they are biodegradable. This does not necessarily mean that they are compostable. For a material to be able to be compostable it must be proven that the material breaks down because microorganisms are consuming the material and releasing carbon dioxide. Some materials using the term biodegradable are disintegrating due to chemical reactions, which break the polymer chains into smaller components and result in microplastics being left in the environment. These are also known as oxo-degradables.

Internationally, labelling standards have been developed to help communicate which materials can be composted. These are issued based on scientific tests that give evidence of both consumption of the plastic by microbes and also demonstrate that the material is not toxic by testing seedling and/or worm growth.

Due to the recent commitments to make all plastic packaging reusable, recyclable or compostable by 2025, the use of compostable plastics in New Zealand will most likely increase. This creates an opportunity for new, innovative compostable packaging solutions, but more critically a need for better communication about what can be composted and where. Clear and reliable labelling claims are needed and hopefully, this will lead to more industrial composting facilities accepting the compostable packaging into their facilities.

Lou Sherman is the Packaging Research Leader at Scion and has a background in packaging development.