Spectroscopic Standard Could Help Revolutionise the Analysis of Plastics

Physical Sciences︱Polymateria The team at Polymateria are dedicated to developing truly biodegradable plastics. Spectroscopic standard could help revolutionise the analysis of plastics

Plastic pollution is an environmental catastrophe in progress. 32 percent THE MICROPLASTIC of the plastic we use escapes into the environment and only nine MEGA- PROBLEM percent currently gets recycled. Fugitive plastic products often But what do we know about plastic in environment. So, what can be done to SETTING NEW STANDARDS CI values; with so much inconsistency undergo various forms of environmental degradation, which lead to the the environment, and why is it such an tackle the problem? Plastic degradation is caused by between different techniques, the metric formation of microplastics. British company Polymateria have developed alarming prospect? numerous factors, including extrusion becomes as good as useless. additives for conventional plastics which facilitate biodegradation if they POLYMATERIA’S SOLUTION manufacturing of products and aging due escape the waste stream. This fresh approach is also a rigorous one. Global annual production of plastic British company Polymateria are to use, especially in the case of outdoor COMPARING THE The team at Polymateria noted that conventional methods to determine waste continues at a monumental scale working “to develop technologies for applications. The ability to predict the CARBONYL INDICES carbonyl index, a measure of plastic durability or decay, lacked and increases every year. Meanwhile, plastics that impart biodegradability lifespan of a plastic product, whilst it is In a paper published earlier this year, coherence: there was no agreement in the industry about what type of global waste management streams should they become plastic pollution in use, is of critical importance to both scientists at Polymateria compared the analysis works best. Their proposal – to standardise the use of Specific fail to keep pace with the growing on land in our environment”. plastic manufacturers and consumers. precision and accuracy of several of these Area Under Band (SAUB) analysis to determine carbonyl index – has global population and increased Furthermore, the potential to prove the methods for determining carbonyl index. now been taken up by the American Society for Testing and Materials, consumerism. Each year, megatons Polymateria have designed an durability of a material under natural The most traditional IR spectroscopy as well as the British Standards Institute, as the preferred way to assess of synthetic plastics leak into the ’innovation inside’ methods rely on plastic transformation. environment, around 10 megatons and manufacture transmission of light of which enters the oceans. The rest, technologies for Problematically, many studies have through a material, but a staggering 40 megatons, remains various types of this method is mostly million tonnes of plastic Plastic packaging is the primary on land and is considered ‘terrestrial common plastic stated carbonyl index values with outdated: it is only were created in 2015: driving factor for plastic generation, fugitive plastic’. products that are wildly different values, making really applicable for 381that’s roughly two-thirds accounting for almost 50 percent designed to impart thin films of plastic as the mass of the human population (Our of the plastic made worldwide. In As these plastic products break down time-delayed comparisons meaningless. larger chunks need to World in Data). Synthetic plastics are less this context, it is hard to ignore the they form microscopic fragments known biodegradability. be pressed into shape than a century old but, since the mass reason plastic is so popular: it’s cheap, as microplastics. The key environmental Their technology can be used environmental stresses (sunlight, wind, to enable testing which can be difficult for expansion of plastic production in the versatile, mouldable, light, and – risk is that they are biologically inert. alongside common plastics, like rain, etc.) is essential to aid and advance plastics made brittle by weathering. ‘50s, 5800 million tonnes of the plastic crucially − it doesn’t break down easily. Therefore, over time, they bioaccumulate polyethylene or polypropylene. Their the understanding and development produced has been disposed of, only nine Plastic can sometimes be used too in the natural environment. aim is to ensure that their plastic of new environmentally inert materials Measuring the carbonyl index of a percent of which has been recycled and a conveniently and for the same reason products become biodegradable that do not add to plastic pollution, plastic requires comparing the peak staggering 32 percent estimated to have can often be disposed of without We know that we need to limit the wax rather than fragmenting into bioaccumulation and consequent in the carbonyl group spectrum to escaped into the natural environment. consideration. amount of plastic and microplastic microplastics, should they slip through environmental damage. another reference peak. When analysing pollution, however it is not as simple as the net of waste management systems thicker or more opaque materials using turning off the ‘plastic tap’. In order to and end up in the environment, Infrared methods are commonly used transmission spectroscopy the reference enable the removal of standard plastic thereby avoiding further contribution to test plastics, like polypropylene peak becomes saturated, giving an products from production, sustainable, to the problem of plastic pollution. and polyethylene, and provide a value inaccurate value for the carbonyl index. suitable replacements must be secured referred to as the carbonyl index (CI), one This can happen with materials even as as plastics have a plethora of vital uses. To create this new technology, the of the many metrics used to interpret thin as 0.1 mm. These include: single-use sterile medical team of scientists at Polymateria have the breakdown of a material. To date, equipment, to reduce the risk of cross- had to revolutionise scientific thinking however, there has been no consensus ATR-FTIR (Attenuated Total Reflection – contamination in hospitals; hygienic on the breakdown process of different regarding which of the multiple possible Fourier Transform Infra-Red) spectroscopy food transport and storage solutions, to plastics under different environmental techniques should be used to calculate CI has largely superseded transmission IR

Photo KR/Shutterstock.comPhoto reduce food waste; lightweight transport conditions. This has meant going as the definitive technique. By comparing spectroscopy. In ATR-FTIR, a crystal in and efficient insulation, to reduce beyond standardised testing practices and contrasting each technique using the contact with the surface of the material fossil-fuel based energy consumption. and has led to the development of same material, the team at Polymateria passes light through the surface of the Given the current scale of plastic use it is enhanced new methodologies for found that the different methods of sample and is reflected back out to a inevitable that some will escape into the plastic analysis. calculation each provided wildly different detector. Almost no sample preparation

www.researchoutreach.org www.researchoutreach.org far more accurate in observing the the biodegradability performance of a In the environment, plastics tend to degrade to chemical change of a plastic sample plastic, to verify claims made by plastic Behind microplastics, causing over time. They have shown that the companies that their products are further problems. SAUB method outperforms other biodegradable. In this BSI standard, the the Research stated methods of determining CI key goal for achieving biodegradation and can even be used to compare is the chemical transformation of the Polymateria one test sample of plastic to another. plastic material into a bioavailable wax. They have also demonstrated that the The SAUB CI measures the extent of this E: [email protected] W: https://www.polymateria.com/ method works for both polyethylene transformation and allows for a number and polypropylene, allowing for to be assigned to the wax determining Further information • ASTM webpage on Working Group for Carbonyl Index Standard: https://www. comparisons to be made between its CI. This, in combination with other astm.org/DATABASE.CART/WORKITEMS/WK65360.htm these two different types of plastics. analyses, determines if a bioavailable • LinkedIn for C Wallis: https://www.linkedin.com/in/christopher-wallis-phd-mrsc- wax has successfully been produced. mrsb-84729833/ • https://www.linkedin.com/in/gavin-hill-a4233729/ The team also stress-tested their The key shift here is to move away from LinkedIn for G Hill: • BSI Group: https://www.bsigroup.com/en-GB/ preferred method by analysing a plastic unsubstantiated claims and to produce • Polymateria: https://www.polymateria.com/

Jay-Dee/Shutterstock.com undergoing accelerated weathering. numerical data on the performance • ASTM working group: https://www.astm.org/COMMIT/SUBCOMMIT/D20.htm Results for the SAUB showed better of a plastic material in line with other • Link to Paper on Identification of Marine Microplastics: https://www. sciencedirect.com/science/article/abs/pii/S0025326X17310949 is needed, and samples can be analysed notably it specifies the signals that are flexibility than other methods, increased International Standards. quickly at low cost. being analysed and defines the area to reliability, and better precision for measure in each case, thus removing identifying change over the course TRUSTING PLASTIC Research Objectives There are multiple ATR-FTIR methods the need for an operator to make an of the weathering, including when TO ‘STAY’ OR ‘GO’ Dr Christopher Wallis, Dr Gavin Hill and colleagues at Polymateria have been able to with different light angles and crystal arbitrary decision as to which is the the plastic was highly embrittled and Plastic pollution is one of the key standardise the method used to calculate the carbonyl index with important ramifications for types, which can affect the depth correct reference peak to analyse. difficult to physically handle. environmental issues of our time. Given measuring the accurate level of chemical transformation undergone by a plastic material. that the light penetrates the material. that plastic is so valued and valuable to Problematically, many studies have It also makes more intuitive sense PLASTIC ANALYSIS WE CAN TRUST the global economy and our way of life, Detail stated CI values without specifying the than using peak heights. In infrared The team at Polymateria were keen to its production will inevitably continue. testing of the company’s bespoke type of spectroscopy used, and some spectroscopy the height (or intensity) of ensure that their discovery did not remain In the meantime, we need to improve Dr Christopher Wallis I-HUB Translation & Innovation Building bio-transforming technology for even describe using transmission IR a peak is related to the concentration the intellectual preserve of academics. waste management systems so more 84 Wood Lane plastic material, by both an internal spectroscopy despite testing materials up of a chemical species. But in infrared Despite successfully fulfilling the rigorous plastic is successfully recycled and more Imperial College London White City interdisciplinary team and extensive to half a millimetre thick – five times the spectroscopy very similar but chemically criteria of academic peer-review in gets collected responsibly, so that as Campus network of third-party laboratories and London academic institutions. desirable thickness, leading to CI values different species sit alongside, and publishing their work, they are now going little plastic as possible ends up on land UK being obtained of questionable validity. even overlap, each other, in the same a stage further in converting the SAUB and in the ocean. W12 0BZ Funding area of the spectra. This means that the methodology into a Standardised Test Polymateria Limited height of the peak is not as informative Method. Through a working group at the What scientists, like those at Polymateria, Bio LOOKING UNDER THE CURVE Dr Christopher Wallis (MRSC, Collaborators Having reviewed the common as the combination of both height and American Society of Testing and Materials are doing to help reduce this problem is MRSB), Vice President, Innovations • Impact Solutions spectroscopic methods, and performed breadth, i.e. the area under the peak. The (ASTM), the SAUB methodology is innovating to create new technologies (Polymateria), leads the Research and • American Society for Testing and their own tests, the Polymateria team height may indicate that one chemical undergoing further technical scrutiny and for plastics, as well as new plastic Development team at the company’s Materials (ASTM) International London head-office. Dr Wallis’ focus • British Standards Institute (BSI) proposed that the methodology for species is at higher concentrations than review on its way to becoming an ASTM materials. These materials need to be is the design, development and • Dr Gavin Hill (Polymateria) generating CI International Test either more durable (i.e., resistant to values should be Method. environmental decay if littered) or more standardised. In Polymateria’s approach, the area of the environmentally responsive than those References The goal is to before (i.e., use the environment to help peaks gives more accurate information on • Almond, J., …, Wallis, C. (2020). Determination of the carbonyl index of Their tests found give plastic change themselves into biodegradable polyethylene and polypropylene using specified area under band methodology that the most the total concentration of CI species. companies, as well materials, if they become littered). with ATR-FTIR spectroscopy. e-Polymers., 20, 369-381. reliable method as environmentalists, • Wallis, C. (2019). Terrestrial fugitive plastic packaging: the blind spot in resolving for determining consistent carbonyl the others, but the area of the peak a trusted tool that can be used to assess In both cases, new analytical tools will be plastic pollution. Green materials., 1900044. indices is the Specified Area Under gives the total concentration of all the the level of chemical change a plastic has necessary to prove the performance of Band (SAUB) method, a new way of chemically similar species in the test undergone either in its designed use or in these novel innovations. Methodologies interpreting the same spectroscopic data sample, a far more useful indicator. its misuse, as a fugitive plastic on land or that are accepted by the rigorously Personal Response from ATR-FTIR spectroscopy. Rather than Peak areas are therefore more reliably in a marine environment. precise world of academia, and yet Why do you think your team were the first to highlight the inconsistencies taking the height of the carbonyl peak representative of what is ideally being are also used actively by industry, can in calculating carbonyl index? and comparing it to the height of the measured in the spectroscopic process – Additionally, though only published provide a clear pathway for bringing The team at Polymateria were the first to highlight this and make a huge effort reference peak, the SAUB method takes the concentration of all carbonyl species this year, the SAUB IR spectroscopy greater confidence to the general public to create a more definitive method, because we were interested not just in the CI the area under the carbonyl peak and as an indicator of the extent of chemical forms a key part of a new British that a plastic material will either be value, but the change in the CI value over time. When a value changes over time it is compares it to the area under a universal change the plastic has undergone. Standards Institute (BSI) standard durable or decay. The SAUB CI method especially important to be able to measure it as accurately as possible. We noticed that by combining the changes that may occur either to the height or the breadth of reference peak for both polyethylene and specification, designed to determine and the way it has been created, is a the peaks, we were obtaining far more accurate information, as the plastic sample polypropylene plastics. Through their work, it became the biodegradability of plastics in the good example of this collaborative chemically changed over time. This is critical to evaluating plastics in the natural clear to Polymateria’s team that the open-air terrestrial environment. In this approach of bringing credible innovation environment as the length of exposure they have is linked to the amount in which This has some distinct advantages change in the area of the signals case, the SAUB CI method provides to evaluate the types of plastic products they can be chemically altered. over conventional techniques: most in the infrared measurements was one of the key indications in assessing we all use in our everyday lives.