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Basics Biodegradation: One concept, many nuances Over the course of the 20 th century, we have become adapted to plastics and production and consumption have skyrocketed these past decades. Plastics have many different properties, are lightweight, can easily be formed into any shape and most importantly are extremely durable. Nowadays, it is almost impossible to imagine a world without plastics. As a small thought experiment, it is interesting to imagine your room without plastics. However, it has become clear that the durability of plastics is also the biggest disadvantage. Unmanaged disposal of plastic waste in the environment results in visual pollution nowadays appearing in the news daily. As a consequence of this pollution, the (micro)plastic accumulation in nature over time increases. Over the last few decades, this growing concern about plastics has encouraged governments and international governing bodies to implement legislation and directives with specific requirements on the reduction, re-usage, and (organic) recycling of plastic products. These legislative matters together with increasing awareness amongst consumers and producers emanated the appearance of (bio)degradable plastics in the market. Nonetheless, there is currently still a lot of confusion on the definition of (bio)degradable plastics and their actual behaviour in the environment. As misinformation might give rise to greenwashing and incorrect expectations for these products, causing more harm than good for the environment, clear terminology and communication between all parties are of utmost importance. Topics like bioplastics, biodegradability & compostability will be rolled out in the paragraphs below. Bioplastics… What’s in a name? The question “What are bioplastics?” might be more difficult than it seems. What comes to mind when you think of bioplastics? Plastics derived from natural materials? Plastics that can be biodegraded? Or are bioplastics both of the above? (Fig. 1). First of all, it is important to note that the nature of the raw material is not directly connected to its potential to biodegrade. Plastics of petrochemical origin can be biodegradable while plastics from natural feedstocks – known as biobased plastics – are not necessarily biodegradable. Examples of biobased but non-biodegradable plastics include bio-PE and bio-PET. Since these have an identical chemical structure as their petro-based alternatives, these are not biodegradable and should be managed in the same way as conventional PET. Vice versa, not all petro-based polymers are non-biodegradable. Examples like PBAT and PCL can be biodegraded in compost. The fact is that the term ‘bioplastics’ is not clearly defined and can be misleading or confusing to customers. Therefore, experts are tending towards using biobased plastics or biodegradable plastics over the term bioplastics. Complete biodegradability Biodegradation can be defined as the biochemical conversion of materials into natural substances like CO 2 and water (and CH 4 if biodegradation is anaerobic) through the activity of micro-organisms (Fig. 2). It is important to note that not all organic carbon is converted, as a small part is assimilated as microbial biomass. To take this biomass assimilation into account, biodegradation is considered complete if 90 % conversion of organic carbon to CO 2 is achieved. It is important to understand this may absolutely not be seen as 10 % microplastics remaining. Conversion to CO 2 is the only correct way to quantify biodegradation. Parameters like visual disappearance of material, molecular weight reduction, loss of technical material characteristics are often wrongfully used to make claims on biodegradation. However, these parameters only prove biological activity but do not guarantee actual biodegradation. Biodegradation and the importance of the environment Biodegradation is caused by enzymatic, microbial, and/ or fungal activity. As microbial ecology varies from one environment to another, it is important to understand that biodegradability is highly dependent on the environment. The claim of biodegradability should always be linked to a specific environment. For instance, lignin-rich materials (e.g., hardwood) may biodegrade relatively fast in environments with fungi present like in soil or compost, while these materials can persist for decades in water or landfills. There are cases of perfectly conserved newspapers (high lignin content) from the 1960s found in landfills today. As another example, standard PLA requires a thermal trigger (> 50 °C) before the biodegradation process can be started. These high temperatures are achieved in industrial composting facilities or anaerobic digesters operating at high temperatures. However, when thrown in the composting heap at home this material will not biodegrade in the required time frame. As this can be very frustrating for customers it is important for producers to clearly indicate in which environment the product is biodegradable and generic claims on biodegradability should not be made. Composting plants are very diverse and may operate at a higher or lower technology level, with different loading rates, process durations, temperatures, etc. Also, our planet offers a great variety in soils, fresh & marine waters. Some soils may be extremely hot and dry, while other soils can be wet and almost anaerobic. It would be impossible and impractical to have different testing standards for each possible environment. It is therefore important to have reliable test methods that can be used to prove biodegradability of materials in various environments. The purpose of lab testing is to prove the inherent nature of the material to biodegrade under a given set of environmental conditions. It is also important that results are accurate and 50 bioplastics MAGAZINE [<strong>01</strong>/22] Vol. 17
By: Bruno De Wilde, Managing Director, Astrid Van Houtte and Tristan Houtteman Marketing & Sales Engineers OWS Gent, Belgium Basics reproducible. Lab tests are per definition always optimized but not accelerated, meaning that all parameters like temperature, pH, nutrients, etc. are optimized except for the parameter which is studied. For biodegradation, testing this limiting parameter will be the carbon source. Furthermore, a positive reference material (easily biodegradable e.g., cellulose) is also included and used to validate the test. The recurring question often asked is whether materials that pass testing at optimized test conditions will also biodegrade in the actual environment. The answer is that in reality, the same level of biodegradation will be obtained, yet, the rate will depend on local conditions (temperature, humidity, etc.). Composting, so much more than biodegradation A well-known managed end-of-life environment is compost. Very often compostability is used interchangeably with biodegradability. The fact is that compostability is a much broader concept. One European standard with requirements on biodegradability is EN 13432 (2000) on industrial compostability of packaging, covering also requirements for chemical characteristics, disintegration, and ecotoxicity. All four requirements must be met before a product can be considered compostable. Compostable products will therefore be biodegradable under composting conditions but not necessarily vice versa (Fig. 3). During chemical characterization, concentrations of heavy metal & fluorine are compared to pre-defined limits. The goal of ecotoxicity testing is to check whether degraded material, present in the produced compost, does not exert any adverse effects on test species (plants and/or earthworms). Biodegradation can be seen as degradation on a biochemical level, while disintegration is the physical breakdown or fragmentation of material into smaller particles. In real-life composting, disintegration & biodegradation are closely intertwined. To further illustrate the difference between biodegradation & disintegration one can take wood as an example. Wood is biodegradable, that is a fact. However, not all wood is compostable. A small twig will disintegrate almost directly, while a big tree trunk might take several decades to disintegrate. Another example is conventionally non-biodegradable plastics enriched with additives which are said to improve degradation. These additives can indeed enhance disintegration of polymers and are used as a solution for the visual contamination of litter. However, complete biodegradation is not really proven and the residual microplastics may persist in the environment for a very long time. Therefore, these additives are regarded more as an out of sight, out of mind solution, rather than as a sustainable solution to combat plastic pollution. Uncontrolled environments Not all plastics end up in managed end-of-life sites. Some materials may unintentionally disperse in uncontrolled environments like soil, waterways, or marine due to littering AEROBIC BIODEGRADATION Fig. 1: biobased plastics, biodegradable plastics Microorganisms + O 2 Biochemistry CO 2 H 2 O Humus Biomass Fig. 2: “The circle of life” Environmental safety Chemical characteristics (Heavy metals) Ecotoxicity (Effect on plants) Fig. 3: All four requirements must be met Organic matter Degradation Biodegradation (Degradation on a chemical level) Disintegration (Degradationon a physicallevel) Basic Photosynthesis 7 bioplastics MAGAZINE [<strong>01</strong>/22] Vol. 17 51
Page 1 and 2: Bioplastics - CO 2 -based Plastics
Page 3 and 4: dear Editorial readers Alex Thielen
Page 5 and 6: Bio-based acrylonitrile for carbon
Page 7 and 8: WWF released new position: Chemical
Page 9 and 10: Engineering tomorrow’s materials
Page 11 and 12: and market development update Marke
Page 13 and 14: COMPEO Leading compounding technolo
Page 15 and 16: io PAC bioplastics MAGAZINE present
Page 17 and 18: 7 th PLA World Congress 24 + 25 MAY
Page 19 and 20: 1800 — 1600 — 1400 — 1200 —
Page 21 and 22: Symbio has also been selected for o
Page 23 and 24: BIOMOTIVE The amount of plastics us
Page 25 and 26: fossil available at www.renewable-c
Page 27 and 28: Automotive bioplastics MAGAZINE [01
Page 29 and 30: Automotive UBQ is also used in the
Page 31 and 32: cradle-to-gate emissions. While car
Page 33 and 34: BOOK STORE Conference Review New Ed
Page 35 and 36: Download the free bioplastics MAGAZ
Page 37 and 38: Foam order to obtain pure foam part
Page 39 and 40: New 3D printing powder for food ind
Page 41 and 42: PLA crystallization and drying Now
Page 43 and 44: However, the resulting JRC “Plast
Page 45 and 46: Celebrating 85 years of twist wrapp
Page 47 and 48: Suntory introduces 100 % plant-base
Page 49: Recycled ocean plastic for Ford Bro
Page 53 and 54: Automotive 10 Years ago Published i
Page 55 and 56: Sukano AG Chaltenbodenstraße 23 CH
Page 57 and 58: Vol. 17 ISSN 1862-5258 Subscribe no
Page 59 and 60: SMART SOLUTIONS FOR EVERYDAY PRODUC

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