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Abstract

The wood industry relies heavily on thermosetting resins such as urea-formaldehyde, polyurethanes, and epoxies for the manufacturing of engineered wood products. While these adhesives offer strong mechanical performance and moisture resistance, their environmental and health impact raise concerns. Additionally, the irreversible nature of these cross-linked networks prevents efficient material separation and recovery at the product's end-of-life.Bio-based debondable adhesives, capable of undergoing controlled debonding under specific stimuli, present a promising solution to enable disassembly and recycling of multilayer wood products, improving their sustainability.In the initial phase of this research, efforts were directed towards modifying potato starch (St) with maleimide moieties (6-maleimidohexanoic acid, 6-MHA). Both suspension and solution methods were explored. Maleimide grafted St (St6MHA) synthesized via the solution method was selected for further study due to the higher degree of the starch’s hydroxyl groups substitution by 6-MHA and the lack of St granule structure preservation of the suspension method .Kraft lignin (KL) was functionalized with furan groups to enable the formation of a Diels–Alder (DA) network with St-6MHA. Experimental results confirmed the successful formation of a reversible DA network, which formed at 65 °C over 48 h and dissociated at 135 °C after 3 h. Blends of these materials were used to bond furfurylated beech veneer, achieving an average tensile strength of 5.00 ± 0.5 MPa. Controlled debonding was observed at 135 °C after 4 h, demonstrating the system’s potential for recyclability of wood products.In a final step, a Schiff base network was developed using dialdehyde starch (DAS), hexamethylene diamine (HMDA), and amino-functionalized carbon dots. The incorporation of carbon dots showed promise in accelerating the curing process and enhancing the mechanical strength of the DAS:HMDA adhesive system. A tensile strength of 3.96 ± 0.18 MPa was achieved after just 300 sec of pressing at 160 °C, highlighting its potential as a fast-curing, bio-based adhesive.

Keywords

starch; Kraft lignin; click-chemistry; covalent adaptive networks; ondemand debonding; carbon dots

Published in

Acta Universitatis Agriculturae Sueciae
2025, number: 2025:55
Publisher: Swedish University of Agricultural Sciences

SLU Authors

UKÄ Subject classification

Other Environmental Biotechnology
Bio Materials

Publication identifier

  • DOI: https://doi.org/10.54612/a.115vp2i3dk
  • ISBN: 978-91-8124-039-9
  • eISBN: 978-91-8124-085-6

Permanent link to this page (URI)

https://res.slu.se/id/publ/142456