22 February 2021

Developing bio-based materials for a greener world.

Researchers at the University of Sheffield have been developing a range of bio-based materials with the potential to replace non-recyclable plastics in packaging applications and are now making progress on up-scaling production processes.

SEM image of freeze dried Bacterial Cellulose, showing the fibrous nature of the material.

Having developed a range of bio-based materials with the potential to replace non-recyclable plastics in packaging applications, scientists at the University of Sheffield are now making progress on up-scaling production of a selection of these materials in preparation for potential commercialisation.

Due to the high annual consumption of polymers/plastics, green, biodegradable and biocompatible polymers are in high demand both for bulk applications and for medical applications. 

The ECOFUNCO project involves institutions from around Europe working on the development of eco-friendly bio-based coatings which can be used in applications including food packaging, personal hygiene, disposable food and drink containers and non-food packaging. The aim of the project is to create coatings that exhibit improved performance compared to existing products, but with more sustainable end-of-life options. 

The research taking place at the University of Sheffield, led by Professor Ipsita Roy of the Department of Materials Science and Engineering, centres around the development of the base materials for the green coating formulations. Other collaborators in the consortium are formulating novel coatings using these and other materials, to be applied to plastic and paper substrates in order to impart hydrophobic (water stable), oxygen barrier and anti-microbial properties.

Cellulose is the most widely-available renewable material on Earth. Using cellulose-derived materials to replace fossil-based plastics in a range of consumer products, such as disposable food products or personal care items would make a considerable contribution to Europe’s environmental ambitions.

However, because cellulose materials in their current form have some limitations (such as poor barrier properties), they are often mixed with polyethylene, which limits its recyclability and undermines the environmental benefits. That is why alternative bio-based coatings are being developed to achieve the properties required. It is the combination of the substrate and the coating that will lead to the use of biodegradable, biocompatible and environmentally friendly materials in packaging applications where today non-recyclable materials are used.

The materials under development in the Sheffield labs fall into two classes: Bacterial Cellulose and Polyhydroxyalkanoates (PHAs).

Pure Bacterial Cellulose in pellicle form

Bacterial Cellulose is produced by bacteria, as an extracellular polymer in the form of a pellicle, or a thick layer. It is highly biocompatible and biodegradable, and possesses hydrogel properties which make it suitable for use in medical applications, eco-friendly coatings, and as a substitute for paper substrates without the need for further purification. It has a highly porous and crystalline nanofibrillar structure, has high water holding ability, hydrophilicity and excellent mechanical properties.  In ECOFUNCO this is being used for water-based coating applications.

Sample of Purified Polyhydroxyalkanoate

PHAs are polyesters produced as intracellular granules by bacteria and can be produced using low value substrates such as waste frying oil, agricultural waste, biodiesel waste and municipal waste. The polymer is produced by bacterial fermentation followed by extraction of the polymer from freeze dried cells. These polymeric materials are environmentally friendly and biodegradable in both soil and marine environments, recyclable, and have a range of mechanical and thermal properties. The low melting elastomeric PHAs are excellent for packaging and coating applications. PHAs are also highly biocompatible and bioresorbable, hence are highly promising medical materials.

For both types of materials, researchers in ECOFUNCO have been experimenting with different coating formulations, and so far results are looking very promising. A variety of other candidate materials are being shared with other ECOFUNCO consortium members for investigation into their suitability for use as green coatings.

In addition, the Sheffield research group, which comprises Dr David A. Gregory, Dr Lakshmi Tripathi and Mr Emmanuel Asare, has developed methodologies for scaling up the production of PHA materials in preparation for potential commercial applications.

The ECOFUNCO project is funded by the Bio-Based Industries Joint Undertaking (BBIJU)/H2020, and is led by Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM) in Italy. The consortium includes academic and industrial partners from Italy, Spain, Germany, Turkey, Croatia, Belgium and Israel. Industrial partners include Consorzio Prosciutto di Parma  CPP  Italy (Parma Ham producers) and Huhtamaki HUH Germany.

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