A Deeper Green: How Research around Sustainability is Evolving
It might seem longer, but it was only a few years ago that sustainability in consumer goods packaging was an optional extra. In general, there was very little urgency about innovation in this area, plastics was not a battleground, and only a minority of consumers, retailers and brand-owners showed any real commitment to a focus on the environment.
You may question definitions of ‘real commitment’, but today, for all of these groups, sustainability in packaging is a hard subject to ignore. Brand-owners and retailers are falling over themselves in the rush to find ‘plastic-free’ alternatives, and even when consumers do not have a clear idea of what the packaging around their favourite products actually does, they increasingly have robust views on what it should be made of.
There will naturally be plenty of papers dedicated to different aspects of sustainability at the IAPRI Symposium at the University of Twente, the Netherlands (11-14 June 2019).
Biodegradable and compostable packaging materials remain a lively area of research, notably where they help to ensure that food waste ends up in some sort of ‘organic recycling’ rather than landfill.
PLA, PHA and other biopolymers
Carlos Diaz is part of a Rochester Institute of Technology (RIT) team which has worked on thermoformed trays combining different biodegradable biopolymers. He explains: “As biopolymers find more applications, the question becomes how to fine-tune properties, functionality and even biodegradation rates.”
In this case, polylactide (PLA) was blended with a compound based on polyhydroxyalcanoate (PHA) and the rubbery biopolymer polycaprolactone (PCL), with and without calcium carbonate. The aim was to produce fully biodegradable sheet for thermoforming at a pilot scale and compare biodegradation in the different variants, in particular varying the amounts of PCL and calcium carbonate.
“We’ve explored co-polymerisation technology as a means to fine-tune biodegradation rates,” says Diaz. “Another question which has arisen is the use of trigger mechanisms which kick-start accelerated degradation at the product’s end-of-service.”
Degradation was checked for at intervals up to the 60-day end point. The results, which will be presented at Twente, demonstrate that fully biodegradable thermoformed trays can be reliably manufactured even with a high mineral content, he says.
Mineral content of up to 30% affected the optimum forming temperature, but did not compromise biodegradation. On the contrary, says Diaz: “It seems that calcium carbonate helps expose more [surface] area for hydrolysis and microbial degradation, showing as slightly higher degradation at the time the test was stopped.”
Despite the increased interest in PHA at a commercial level, PLA remains “the most abundant available commercial biobased and compostable polymer”, says Rafael Auras at Michigan State University (MSU), and of course, its applications go well beyond packaging. “However, it also has shortcomings such as fragility and low barrier to oxygen and water, so we have been working on improving those properties,” he explains.
In one study to be presented at the June Symposium, the MSU team measured the thermo-mechanical properties of PLA using dynamic mechanical analysis, and then sought to adapt those properties by immersing the material in different alcohols and their aqueous solutions. The study concluded that it provided an initial understanding of how properties can be changed and how this knowledge could be applied to packaging.
But these are not the only properties and performance characteristics of PLA requiring attention. Auras says: “Besides these shortcomings, the organic vapour and liquid mass transfer properties of PLA have barely been investigated. This knowledge is crucial if we want to develop novel PLA packages and applications in contact with food and pharmaceuticals.”
This compares with PLA’s barrier properties towards oxygen and moisture, which are relatively well-known.
Further work, this time carried out in co-operation with Fraunhofer IVV, Germany, aims to address this lack of data with regard to PLA and organic molecules, and this will also be aired at Twente. Frank Welle at Fraunhofer explains that diffusion coefficients were obtained from permeation tests using alkane and alcohol organic molecules with different PLA film thicknesses. Results were compared with known data on polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).
Monomaterials and recyclability
Making plastics structures more readily recyclable while safeguarding supply-chain performance represents another prime area of research into sustainable packaging.
At Nofima, Norway, Marit Kvalvåg Pettersen is involved with no fewer than three papers for the IAPRI Symposium. The common thread running through them is the drive to find monomaterial film structures which can replace complex laminates. If supply chain partners cannot drop plastics packaging altogether, many are eager to move to polymers which can at least be recycled.
One study, which is part of the wider FuturePack project, examines options for replacing a polyamide/polyethylene (PE) structure with a monomaterial polyolefin alternative. In a tray, the team used a combination of a drip pad and a CO2 emitter. In modified atmosphere packaging (MAP), this can be used to compensate for gas which is absorbed by the product. But here, it has an additional function. “In our study, the CO2 emitter was also tested since the monomaterials we applied have quite low barrier properties, so the diffusion of gas from the package to its surroundings is higher compared to high-barrier materials,” says Pettersen.
In another study, her team evaluated the shelf-life of fresh salmon in monomaterial polyolefin film used to replace a PET/PE structure.
Often in these projects, says Pettersen, the challenge is partly about increasing the shelf-life capabilities of monomaterial films, and partly about establishing exactly how much shelf-life is actually required by each product and supply chain.
She adds: “We have also started a new national project specifically to do with reducing plastics. This is partly to do with design for recycling. Even with a barrier layer, it is possible to recycle polyolefins if that barrier layer is thin enough.”
Some of the research to be presented at the Twente Symposium is still so ‘raw’ that details are not yet available. At the Danish Technological Institute (DTI), Søren Østergaard and his team have been investigating the possibilities for developing recyclable plastics films for packaging. This is an area where not only fellow researchers but also brand-owners and retailers will be eager to hear the DTI’s findings.
Change is taking place, too, with regard to research into consumer perceptions of sustainability. At the Packaging Technology & Research consultancy in the US, Ziynet Boz has been working with her colleague Claire Sand and with Virpi Korhonen of Package Testing & Research in Finland to identify the gaps in that research.
Boz will present a paper outlining the positives and negatives in consumer-facing aspects of sustainability, both currently and in the past. She will point out some of the key considerations when testing designs and concepts with consumers, as well as wider strategies both for industry and for researchers.
Also taking the consumer as the subject of her latest research, Iris Borgman works in the Design, Production and Management department within the University of Twente’s Engineering Technology faculty. She will tell the Symposium about her latest findings on consumer perceptions of sustainability in packaging, particularly in terms of inter-generational differences.
“For instance, I’ve asked consumers to put different types of packaging for the same product in order of sustainability, together with an explanation, to find out how they judge them and what their current knowledge is,” she says. One example includes different packs used by the Chocomel brand.
When it comes to products such as water and milk, Borgman has also tested preferences comparing standard, more aesthetic and sustainable packs. The ‘designerly’ approach she has chosen includes the use of actual pack designs rather than hypothetical mock-ups, she says.
When preferences between the generations are compared, some of the apparent contradictions can be interesting. For instance, while younger-generation Millennials tend to score highest in terms of environmental awareness, but “there exists a clear pattern of contradiction between what they know and say, and what they practise”, says Borgman.
Conversely, older consumers are more likely to exhibit environmentally-responsible behaviour, she claims, even though they tend to pay more attention to other criteria such as convenience and clear information when it comes to packaging preferences.
One of Borgman’s aims is to use her research to refine design tools to help in the development of packaging that communicates sustainability to younger consumers.
These and many more papers relating both to sustainability and other areas of packaging research will be presented in full at the June Symposium.