The rapid depletion of fossil resources and rising environmental concerns are serious challenges facing the polymer industry which relies on petroleum. The synthesis of green polymers from renewable resources has become a real solution for fossil fuel consumption and the consequent rising environmental menace. Polyesters are one of the foremost versatile polymers widely used in fibres, plasticizers and plastics; the majority of which are produced from petrochemical resources. ECOSYSTEM represents a greener, circular and more sustainable option for the obtention of high performance bio-based polyesters to produce food and pharma packaging and biodegradable agricultural films.
Obtention and application context
Broadly used in plastics and films production, polyesters are polymers formed by ester linkages between the acid group of one monomer and the hydroxy group of a second monomer. For example, a conventional polyester like Polyethylene terephthalate (PET) is typically produced by polymerising ethylene glycol with terephthalic acid to form long ester-linked chains, which are then processed into films, bottles or fibres. In contrast, biopolyesters refer to polyesters that are either partly or wholly derived from renewable bio-based feedstocks, or that are inherently biodegradable, or both. For example, biopolyesters such as Polylactic acid (PLA), Polyhydroxyalkanoate (PHA) and Polybutylene succinate (PBS) are derived from biomass and/or are designed to biodegrade (Polymers, 2020).
Conventional polyesters are obtained via transesterification of diols and di-acids under high temperature and catalytic conditions. They can be conformed either by aliphatic or aromatic monomers or in a combination of both. The resulting polymer is then extruded, drawn or moulded. Biopolyesters follow similar polymer chemistry but use monomers derived from renewable sources such as lactic acid from fermentation of sugar, hydroxyalkanoates made by microbial fermentation and succinic acid from biomass feedstock. In the specific case of PHA-derived, biopolyesters are produced via bacterial biosynthesis of hydroxyalkanoate monomers which are then polymerised (Paradigm, 2022). As for PLA, it is the most well known aliphatic polyester with a worldwide demand of 360 kilo tones in 2013; and it is widely used to as thermoplastic to produce packaging materials (EJCHEM 2022).
Biopolyesters offer several benefits: they are an excellent option for tuning mechanical and barrier properties; and they have great potential for biodegradability or compostability. Biopolymers are mostly used in food packaging such as rigid trays, films, bags. In this context, PLA is a clear example of a widely used biopolyester, especially to produce disposable food containers and trays (Polymers, 2020). Biopolymers are also used in pharmaceutical packaging like blister films, vials, sachets; and also, in agricultural mulching films and covers that can be ploughed into the soil for further biodegradation (Letters in applied microbiology, 2020).
Europe wakes up
The European bioplastics / bio-based polymer market remains relatively small but rapidly growing. According to the industry association European Bioplastics, bio-based plastics account for around 0.5% of total plastics production globally, but production capacity is forecast to rise from ~2.18 million tonnes in 2023 to ~7.43 million tonnes by 2028 (European Bioplastics, 2023).
Conventional polyester production uses fossil feedstocks, high energy input and greenhouse gases yields. Biopolyesters use renewable feedstocks reducing fossil carbon; and often enabling end-of-life options like biodegradation or composting. A study carried out by the European Commission in 2019 reported science-based evidence supporting the benefits of innovative bio-based plastic products and their environmental impact if compared with the corresponding petrochemical-based counterparts. This is a useful tool that reinforces the need of updated bio-economy policies and recommendations as well as urgent EU-level decision making for further implementation of plastic strategies (EU publications, 2019). One of the relevant conclusions of the study states that bio-based plastic products made from good-quality waste matter could bring up 65% greenhouse emissions savings, meaning that products achieved with engineered and intended end of life are a clear opportunity for a more sustainable economy.
The role of ECOSYSTEM in this transition
When sustainably sourced, bio-based production reduces dependency on fossil resources, lowers net carbon emissions and allows to close the loop by obtain products designed for biodegradability and recyclability. Additionally, agriculture and packaging sectors stand to benefit from lighter, compostable or soil-biodegradable materials, which reduces post-consumer accumulation and therefore final release to the environment.
ECOSYSTEM is compromised with this transition. The project seeks to develop a new generation of biopolyesters using building blocks prepared from sustainable sources and technologies while advancing green chemistry and circular economy principles. More specifically, ECOSYSTEM aims to achieve the conversion of furfural and lignin compounds into bio-based aromatic building blocks via mechanochemistry; more specifically into bifuran-type and divanillin-type monomers with high yield and purity levels. Later, the achieved compounds will be transformed into high-performance biopolyesters and copolyesters with good barrier properties for food and pharma packaging applications as well as the manufacture of mulching films. The achieved biopolyesters will be strategically designed to be recycled via solvolysis via microwave assistance and aiming to obtain yields of furan derivatives higher than 95%, consuming only up to 50% of energy if compared to traditional solvolysis; and in a considerably shorter time.
Additionally, ECOSYSTEM aims to produce data and knowledge on the degradability of the achieved biopolyesters in seawater and under composting conditions, as well as testing their reusability into difuran-type catalysts in association with earth abundant metals via mechanochemistry. The project will consider regulatory aspects at every stage during the development and incorporation of chemical additives, as well as a sustainable by design assessment of all technologies involved. An LCA covering social and economic aspects will be performed along the project; and a strategic communication, exploitation and dissemination strategy will be carried out.
In summary, biopolyesters combine the performance advantages of polyesters with more sustainable feedstocks and end-of-life options. Their application in food & pharma packaging and agriculture is growing in Europe under regulatory and market pressure. Though still small in share, the upward trend is clear and initiatives such as ECOSYSTEM demonstrate that it is possible to excel the environmental benefits when the supply-chain is well managed.
References:
- Polymers (2020). Bio-based packaging: materials, modifications, industrial applications and sustainability. – Corina L. Reichert, Elodie Bugnicourty, Maria-Beatrice Cotelli, Patrizia Cinelli, Andra Lazzeri, Ilaria Canesi, Francesca Braca, Belén Monje Martínez, Rafael Alonso, Lodovico Agostinis, Steven Verstichel, Lasse Six, Steven De Mets, Elena Cantos Gómez, Constance Issbrücker, Ruben Geerinck, Dacid Nettleton, Inmaculada Campos, Erik Sauter, Pascal Pieczyk and Markus Schmid.
- Paradigm (2022). Polyhydroxyalkanoate (PHA) biopolyesters Emerging and major products of industrial biotechnology – Anindya Mukherjee and Martin Koller.
- EJCHEM (2022). Bio-based polyesters for ecofriendly packaging materials – Mona H. Abdel Rehim.
- Polymers (2020). Advances in manufacturing and characterization of functional polyesters – Rafael Balart, Nestor Montanes, Octavio Fenollar, Teodomiro Bonorat and Sergio Torres-Giner.
- Letters in applied microbiology (2020). Polyester-based biodegradable plstics: an approach towards sustainable development- S. M. Satti and A. A Shah.
- European bioplastics (2023): Bioplastics market development update 2023.
- Publications office of the EU (2019): Environmental impact assessment of innovative bio-based products. Task 1 of “Study on support to R&I policy in the area of bio-based products and services” – European Union