Considering the limits of petrochemical availability and their toxicity, bio-based alternatives to petrochemical adhesives are necessary.1–3 The aim of this study is to develop bio-based epoxy-cured resins for wood adhesives through chemical modifications. As illustrated in Scheme 1, a simple and effective method for synthesizing fully renewable polyphenol-based composites with epoxide functionality is presented. The modifications, based on hydroxyl-epoxide chemistry, were explored using polyphenols (tannins and lignin) and glycerol diglycidyl ether (GDE) as the components. GDE acted as the crosslinker for the polyphenols,4 facilitating the formation of durable three-dimensional networks. The properties of the formulations were influenced by several factors, including the catalyst, GDE-to-biomass ratio, reaction time, and temperature. These factors impacted the degree of crosslinking and conjugation, which in turn affected viscosity and adhesion strength. The produced adhesives, with honey-like physical properties and ease of application to wood surfaces, demonstrating an excellent adhesion performance of 33.50 ± 4.65 MPa (as shown in Scheme 1), which is more than three times stronger than the European Standard requirements (EN 301–2005, ≥10 MPa).5 Remarkably,
even after being submerged in water for five months under a 1 kg load, the adhesive bond remained intact. The promising results highlight the potential of polyphenol-based epoxy-cured resins for industrial applications and provide valuable insights for the design of sustainable wood adhesives.
Keywords: polyphenols, glycerol diglycidyl ether, epoxy-cured resins, wood adhesives
Authors
Junjie Kang
CNRS, University of Poitiers, Institute of Chemistry of Environments and Materials of Poitiers-IC2MP, Poitiers, France
Karine De Oliveira Vigier
CNRS, University of Poitiers, Institute of Chemistry of Environments and Materials of Poitiers-IC2MP, Poitiers, France
François Jérôme
CNRS, University of Poitiers, Institute of Chemistry of Environments and Materials of Poitiers-IC2MP, Poitiers, France
Sandra Tapin-Lingua
Institut Technologique FCBA, All de Boutaut, 33000 Bordeaux, France
Gilles Labat
Institut Technologique FCBA, All de Boutaut, 33000 Bordeaux, France
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