Totally Nuts – Circular Biobased Thermosets from Cashew Nut Shells

Epoxy thermosets are extensively used as coatings, adhesives and in structural applications as they typically impart outstanding mechanical and electrical properties as well as chemical resistance. The currently used epoxy thermosets are produced from fossil-based non-recyclable materials. To be able to meet the circularity and sustainability goals set by the EU, this needs to change. Biobased epoxy thermosets from residual streams are considered a promising and urgently needed alternative to regular epoxy thermosets.
The Cashew Nut industry could play a significant role in the development of these biobased epoxy thermosets. Global cashew nut production is about 4 million tons/year. The cashew nutshell is currently discarded as waste or used as an inefficient fuel, creating environmental issues. The cashew nutshell contains Cashew Nutshell Liquid (CNSL), which consists of the valuable chemical component cardanol. Cardanol can be used to produce biobased epoxy thermosets with balanced rigid-flexible performance. However, systematic studies about the production, properties, recyclability and commercial opportunities of the cardanol based epoxy thermosets are lacking.
In this project consortium partners Avans, RUAS, Maastricht University, TU/e, Nuts2, Charcotec, NPSP, SABA, and Prokol jointly aim to answer the question: How can we develop sustainable and economically viable biobased epoxy thermosets and composites from cashew nutshell residue?
First the pyrolysis process will be optimized for the effective production of CNSL. Next, the cardanol in the CNSL will be purified and modified to make the recyclable biobased epoxy thermoset. Finally, by adding biocarbon (which is also produced during the pyrolysis of cashew nutshell) to the biobased epoxy thermoset, a composite with enhanced mechanical, electrical, and thermal properties is expected to be obtained.
The success of this project serves as a catalyst for the development of sustainable solutions in the thermoset industry and contribute to a sustainable application of cashew nut residue.

Eindrapportage

Totally Nuts explored how cashew nutshell residues could become a source of chemicals and materials for a more circular economy. The project ran from September 2022 to August 2026 and brought together Avans University of Applied Sciences/MNEXT, Eindhoven University of Technology, Maastricht University and Rotterdam University of Applied Sciences with industrial partners Nuts2, CharCoTec, SABA, Puroc, JiaHua and NPSP. The consortium investigated a stepwise approach combining extraction of cashew nutshell liquid, purification of valuable components such as cardanol, and pyrolysis of the remaining material to produce biochar. Analytical methods and process models improved understanding of the feedstock and supported process evaluation. The project established methods for cardanol modification and developed promising epoxy materials, primers and biochar-reinforced composites. Laboratory experiments and selected industrial processing trials demonstrated their potential for coatings, adhesives and composite applications. The research also identified priorities for further development, including curing behaviour, processing reproducibility and recyclability. Initial economic and environmental assessments helped identify opportunities to improve resource use, reduce processing impacts and guide future development. These assessments provide a foundation for further feasibility studies and scale-up. Students contributed through course projects, internships and graduation research. Scientific publications, conference presentations, workshops, a webinar and public communications shared the findings with researchers, companies, students and wider audiences. Totally Nuts strengthened collaboration across the cashew nutshell value chain and created a knowledge base for turning agricultural residues into useful biobased materials.