How can we tell if flexible packaging products are truly sustainable? Ed Roberts, global sustainability leader at Sealed Air, tells us more.


In discussing sustainable packaging, we first need to understand what sustainable packaging is. Most people accept one or two “sustainable” features – does it have an ecolabel – such as EU Flower, PEFC or FSC? Or, does it possess a defined attribute – such as recyclability, biodegradability, or recycled content? 

However, most scientists agree that a full Life Cycle Analysis (LCA) of 15-plus metrics is the only true determinant of sustainability. The most common of these metrics is global warming potential, better known as carbon footprint or greenhouse gas emissions.

Whatever measures are used may deliver a misleading result. For example, consider packaging systems “A” and “B”. Packaging “A” may have a lower carbon footprint than “B”, but “B” may be better at reducing food waste or product damage which probably has a much higher carbon footprint than the packaging. Therefore, in many situations, it is better to consider what the packaging does, rather than what it is or has.

More importantly, the packaging industry is facing multiple, interrelated sustainability challenges:

  • The circular economy
  • Resource depletion and availability
  • Food waste
  • Climate change.

We should be aware of the impacts of the decisions we make against any of these challenges, and not create or cause unintended consequences, for example by increasing resource use with resultant increased greenhouse gas emissions.

For several reasons, mechanical recyclers find some plastics more difficult to recycle than others. Understandably then, recyclers of plastic want to minimise the number of resin types in the waste/recycling stream. However, the functionality requirements of plastic present a barrier to this aspiration.

Different plastics have different properties. One of the important properties for minimising food waste is the gas barrier – the ability for oxygen or other gases to permeate the plastics. The movement of oxygen contributes to reducing the shelf life of food. Therefore, a very porous plastic such as polyethylene would increase oxygen permeability and result in more food waste. Alternatively, using much thicker plastics for food would cause increased resource depletion.

Plastic packaging comes in many guises, from a utilitarian shopping bag to highly engineered and highly regulated food or medicine packaging. To fulfill the vast range of applications, manufacturers have a huge array of polymers from which to choose.

For example, one resin supplier in the UK produces 119 different grades of polyethylene – each with its own set of chemical and physical properties – molecular weight, secant modulus, tensile elongation, dart drop impact, etc. Packaging manufacturers incorporate specific grades of polyethylene to deliver desired performance such as speed of filling in automated systems, shelf life, protection and food safety.

Consider now the incorporation of mechanically recycled polyethylene into highly engineered solutions. The recycled content is likely to be an amorphous mix of all the different grades and likely to vary from batch to batch, week to week.

For instance, a retailer, e-commerce provider, or pharmaceutical manufacturer cannot accept variation in, quality, filling speeds, shelf life or protection/safety of their goods. As an example, imagine building a premium sportscar with used engine components from a variety of different makes and models. Performance will be compromised.

The solution for the incorporation of recycled content into highly engineered plastic packaging is advanced recycling, also known as chemical recycling or non-mechanical recycling. Unlike mechanical recycling, advanced recycling reduces the plastic to its component parts, typically a liquid and/or a gas.

These components are then rebuilt into the required types and grades of polymers. Using the sportscar analogy, the old steel components are melted down and made into new engine parts specifically designed for that car – performance is maintained. Another advantage of advanced recycling is that it can recycle a greater range of polymer types and is not as sensitive to issues such as contamination, colour, shape, size, form or crosslinking which can be problematic for mechanical recycling.

However, there are two perceived issues with advanced recycling – its carbon footprint versus mechanical recycling, and the very low availability of advanced recycled resins.

While most LCA studies suggest that mechanical recycling has a lower carbon footprint, some suggest the reverse is true. However, there is a strong argument that such a comparison is somewhat meaningless and, perhaps, the LCA for advanced recycling should be compared to incineration or virgin materials.

Furthermore, advanced recycling is a burgeoning technology and industry, and investment is increasing rapidly; Plastics Europe recently reported a significant increase in planned chemical recycling investment: from 2.6 billion Euros in 2025 to 7.2 billion euros in 2030.

The global presence of plastic is not an accident. Its lightness, toughness and cost are among many attributes that can reduce environmental and other sustainability issues. Its circularity is improving but a lot more has to be done. Advanced recycling is a critical element of that journey.