The global plastics industry is currently facing a turbulent period. Geopolitical issues, fluctuating prices and material availability, negative public perception of plastics, and evolving regulations are all key factors affecting the sector. One major trend often overlooked is sustainability. While sustainability in plastics is often viewed positively due to its association with reducing environmental impact, it must also be economically viable. Sustainable products must be affordable to all. By promoting sustainability in compounding, the industry can mitigate the challenges mentioned above and improve the public perception of plastics.
What is sustainable compounding?
Sustainable compounding originated with recyclers who evolved into compounders by using recycled materials as the base for their compounds. It can be defined as a form of compounding that incorporates materials with a lower environmental impact, such as recycled plastics, non-fossil-based fillers, and eco-friendly additives. Although sustainable compounding still has environmental consequences, it is more eco-friendly than traditional compounding and aligns with circular economy principles for plastics.
Market development for sustainable compounds
The market for sustainable compounds is growing rapidly, driven by regulatory pressures, societal expectations, and economic factors like geopolitical tensions and volatile oil prices. The industry's swift pivot toward sustainability demonstrates that these compounds are not just a future trend but a present-day reality. Both the industry and regulators have struggled to keep pace with these changes, particularly regarding recycled materials. However, bioplastics face a distinct challenge: the production capacity is insufficient to meet the rising demand.
Increasing societal demand for sustainable materials has led major industry players to invest heavily in this area, signalling a shift in market priorities.
Key factors driving demand for sustainable compounds
When exploring the factors driving demand, it’s essential to distinguish between recycled materials and bioplastics:
- Recycled materials: Demand is largely driven by regulations and efforts to increase the collection of post-consumer recycled (PCR) materials, focusing on improving their quality. Technological advancements, especially in mechanical recycling, depend on these factors, addressing both quality and quantity issues in recycled materials. It is expected that more technical materials will become available, but specific collection systems need to be defined. For example, PVC is already collected specifically from windows, pipes, cables, and flooring.
- Bioplastics: The main challenge here is availability, which currently lags behind demand. Many companies are working on developing new bioplastics, particularly compostable and renewable varieties, to close this gap. The next step is to enhance their properties to match those of conventional polymers, particularly in injection moulding and technical applications. It is anticipated that global bioplastic production will see significant growth in the next two years.
Trends and influences in sustainable compounding
As the industry undergoes this transformation, several key trends are shaping the future of sustainable compounding:
- Availability and cost: Material availability, price competitiveness, and performance are the top concerns for both PCR and bioplastic compounds.
- Recycled materials: The focus is on developing PCR polyolefins for food-contact applications, improving the recovery of complex materials (such as multilayer or cross-linked materials), and addressing odour removal, particularly for automotive applications.
- Bioplastics: Polyhydroxyalkanoates (PHA) are generating significant interest, especially for packaging and injection moulding. Bioplastics compounded with natural fibres are also gaining traction. While extrusion-based bioplastics have matured, injection moulding still poses challenges.
- Masterbatches: The demand for masterbatches tailored to PCR and bioplastics is expected to rise, and regulations or taxes may further drive this area.
Challenges that require new solutions
A combination of R&D and administrative measures (e.g., improved collection regulations) is crucial for boosting the reintroduction of PCR plastics into the market.
Several technical challenges remain in advancing sustainable compounding:
- Polymer matrix production: Producing the polymer matrix is a major challenge that affects the availability and quality of sustainable compounds.
- Recycled materials: Consistency and quality are ongoing issues. Specific concerns like odour, rheology, colour, and stabilisation need to be addressed to reintegrate recycled materials into the value chain. Pre-consumer waste may provide part of the solution.
- Bioplastics: Key challenges include improving mechanical performance and melt strength for emerging bioplastics.
- Recyclate regulation: Especially for food-contact applications, managing legacy additives in long-life products (such as those from the electronics or PVC sectors) is critical. Chemical recycling is likely to play an essential role here.
Technical areas of interest
Several technical areas are the focus of current research and development:
- Recycled materials: Developing recycling methods for complex materials using compounding equipment that can decontaminate, degrade, and decrosslink them. Efforts are also being made to remove legacy additives from recycled materials.
- Bioplastics: Research is focused on discovering new natural polymers that can be transformed into bioplastics, thus increasing renewability and making better use of biowaste. Reformulating PHA compounds, especially beyond polyhydroxybutyrate (PHB), is another area of interest.
- Recycled fibres: Thermoset-reinforced products from industries like energy, construction, and aerospace are becoming valuable recycling resources, now being used as reinforcing agents in compounding.
- Natural fillers: Significant amounts of biomass are being wasted or burned, contributing to CO2 emissions. These regionally available fillers are increasingly used as reinforcements in plastic and bioplastic compounds.
Although this article doesn’t delve into the compounding process, each material mentioned deserves its own dedicated discussion. Sustainable compounding involves not just selecting the right materials but also managing challenges such as handling, feeding, and mixing more heat- and shear-sensitive materials. Careful equipment selection and conservative processing conditions are critical to maximising the potential of sustainable raw materials. Aimplas, with its focus on sustainability, is directing its research efforts toward these important aspects of compounding.