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CHARACTERIZATION, COMPATIBILIZATION, PROCESSING AND PROPERTIES OF RECYCLED POLYOLEFINS

Periodic Reporting for period 1 - REPOL (CHARACTERIZATION, COMPATIBILIZATION, PROCESSING AND PROPERTIES OF RECYCLED POLYOLEFINS)

Período documentado: 2020-02-01 hasta 2022-01-31

Polymers play a vital role in our lives, as plastic materials are used in healthcare, energy, electronics, security, transport and sustainable development. Nevertheless, the whole value chain connected to polymers has come under scrutiny for its implications in the economy and the environment. A linear plastics economy means that after a first-use cycle, 95% of plastic packaging material value is lost to the economy – some USD 80-120 billion. In addition, a million tonnes of plastic litter end up in the oceans every year causing an alarming problem. In response, polyolefin industries have created the Polyolefin Circular Economy Platform (PCEP), as a European joint industry value chain initiative. For example, Borealis with its partner company NOVA Chemicals and the joint-venture Borouge have started the project STOP (Stop Ocean Plastics) to prevent 10,000 tons of ocean plastic leakage in South-East Asia. The global commitment is to combine the power of innovation, industry, business, policy, and education to eradicate plastic pollution at the source. This commitment implies that all plastic packaging should be collected and safely reused, recycled, or composted. This will offer a root cause solution to plastic pollution with profound economic, environmental, and societal benefits. In addition, another important benefit is that plastic recycling helps cut CO2 emissions, in line with the Paris Agreement and Circular Economy Solutions.

The transition to the circular economy must be made as eco-efficiently as possible, but circularity has to be a priority together with quality and performance to ensure acceptance. Two of the most highly produced polymers are polyethylene (PE) and isotactic polypropylene (iPP) due to their low cost, ease of manufacturing and excellent properties. More than 70 million and 50 million metric tons of PE and PP, respectively, are produced annually and one of the main producers is Borealis group (our REPOL-EID non-academic beneficiary).

Polymer blending is an economic alternative to developing products with tailored properties. However, polymers are frequently thermodynamically immiscible. In the case of PE and PP, their immiscibility produces phase separation and inhibits interfacial adhesion with damaging consequences to thermo-mechanical properties. Roughly 5% of the value is retained when these plastics are mechanically recycled, typically into lower-value products (down-grade recycling), as a result of sorting expenses and degraded physical properties. Compatibilizers open opportunities for upgrade-recycling recovered PE/PP into equal- or higher-value materials with lower categorisation costs during recycling. Because PE and PP are of great economic importance (more than ~$200 billion in annual sales, worldwide), strategies to compatibilize these materials may have considerable potential to affect sustainability and the economy.

The REPOL European Industrial Doctorate (EID) project (Characterization, compatibilization, processing and properties of recycled polyolefins) has the overall objective of training a new generation of doctoral students on cutting edge characterization of recycled polyolefins, compatibilization of recycled PP/PE blends through the selection of suitable compatibilizers or the preparation of polymer blend nanocomposites (PBNANOs) based on recycled polyolefin/PET blends and nanoparticles, while exploring innovative processing routes to tailor morphology and properties. In other words, they will be trained to design and produce plastic materials based on post-consumer recycled plastic waste with an innovative up-grade philosophy, while being coached by expert polymer researchers from academia and industry. The Early Stage Researchers (ESR) will be offered a high-quality individual and networking training program, following the EU Principles for Innovative Doctoral Training, while strengthening the transfer and exploitation of knowledge for circular plastic solutions. Experts at the interface between polymer science and recycling will be highly needed in the near future. REPOL-EID will be established by a consortium of leading European scientists in the academic and private industrial sector of polymer chemistry and materials engineering. The 2 academic beneficiaries: University of the Basque Country (SP) and University of Genoa (IT), together with Borealis as industrial beneficiary (AT) will collaborate on the training through research of three early stage researchers (ESRs) with a highly inter-sectoral and interdisciplinary approach by combining frontier research projects and industrial applications.
Within the first reporting period, there have been advances on each of the three technical workpackages of REPOL project. Thus, model and recycled polymer blends have been molecularly characterised through different characterization techniques (DSC, NMR, CFC) in addition to specialised thermal protocols such as self-nucleation and annealing SSA (WP1). In WP2, the mechanical, morphological, and thermal properties of various blends with and without compatibilizers and nanoparticles were investigated. Compatibilization in model blends was analysed initially for the selection of the best candidates to be tested in recycled materials. Consequently, recycled materials were compatibilized with the best candidates resulting from the selection of the best compatibilization in the model blends, obtaining potentially functional materials in up-graded applications. Finally, in WP3 some preliminary results related to the crystallization kinetics of recycled PE/PP blends under fast cooling conditions have been investigated.

The project objectives are expected to be accomplished within the next two years of the project.

Regarding training activities, the three fellows have attended the 1st REPOL Summer School as well as the local training activities organised by their research host institutions. Besides training activities, fellows have also participated in international scientific conferences where they have had the chance to present their results obtained so far.
The synergetic collaboration between academia and industry within REPOL project will allow the transfer of knowledge and promote the industrial applications of polymer recycling according to market expectations. This will allow us to address economic, ecological, and societal challenges in the framework of the sustainable development goals (SDG).

So far in the consortium of the REPOL project, various significant results have been obtained regarding the complete molecular characterization of polymer blends as well as the obtention of potentially applicable recycled materials with interesting properties. The thermal characterization is also a key factor in the project because it links the inherent properties of the materials with the processability aspects in a way that allows producing efficiently such blends. The generation of scientific knowledge and new products related to polymer blend nanocomposites impacts significantly different economic, environmental, and societal aspects.

This project is seeking a circular economy of plastic, which will allow to reduce the amount of current non-degradable plastic waste as well as reduce gas emissions to the atmosphere. Therefore, the potential socio-economic impact is huge, not to forget the benefits to society.
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