A biobased adhesive capable of competing with industrial adhesives

Used to join two parts and create a compound resistant to high mechanical stress, structural glues contain synthetic materials (polyurethane, epoxide, etc.) made of volatile organic compounds (voc) that are potentially toxic to health and the environment. Given the wide range of applications for these structural adhesives, one of the most pressing challenges is to find alternative materials that are both non-toxic and provide equivalent performance.

This is the task that researchers at the Irstea Center and the Institut Pascal in Clermont-Ferrand have set themselves.[1] By combining their knowledge of the mechanics of materials (specifically, modeling adhesive behaviors) and the design of biomaterials, they created a 100% natural glue using chitosan, a biopolymer manufactured industrially from chitin, found in the exoskeleton of crustaceans or in mushrooms. "Formulated from chitosan, an organic acid and a polyol, the glue we have developed is as efficient as industrial structural glues. It has a mechanical resistance to shearing along the glue line (the reference measurement) that is higher than 7 megapascals and that can reach up 40 MPa,” specifies Jean-Denis Mathias, researcher at the Irstea Clermont-Ferrand Center and co-inventor of the bioglue. This is a remarkable result as until now, no biosourced glue has achieved this threshold.

A promising future

Subject to an international patent[2] and jointly owned by Irstea and the University of Clermont Auvergne (UCA), in 2017 this innovative discovery was awarded the Eco-Innovation trophy by Innovergne, a public organization supporting innovation in Auvergne. With its simple manufacturing process and corresponding low costs, which are in themselves a formidable advantage, this new generation glue seems to have a promising future. “Our belief that this innovation is full of potential is supported by the interest that manufacturers of glues and their raw materials have shown in the product. We are currently working to implement partnerships that will make it possible to start a pre-manufacturing development phase,” notes Véronique Vissac-Charles, head of the Promotion and Transfer unit at Irstea.

An initial trial has already been carried out. The bioglue was used as part of the Demether project,[3] which aims to use agricultural by-products - sunflower stalks ground and bound together using the glue - to create insulation panels for buildings. The resulting composite material was able to rival the mechanical and thermal properties of currently available products on the market.

Potentially transferable to a wide variety of sectors, such as construction, packaging or interior design, the bioglue created by the Irstea and UCA laboratories in Clermont-Ferrand is destined to have a big impact.

Watch the Eco-Innovons 2017 Trophy video

For more information

[1] GEPEB and MMS research themes at the Institut Pascal and the LISC laboratory at Irstea.

[2] High mechanical quality biosourced glue - Patent FR2962738 (Cemagref; Blaise Pascal University; Auvergne University), 2011. Extended to 14 countries, including Russia and the United States in 2017.

[3] ANR Project (2011-2015). Partners: Irstea (LISC, ITAP), GEMH, ENSACF, ENSAM Cluny, Institut Pascal. Coordinator: Jean Marc Gonthier