A lignin-epoxy resin derived from biomass as an alternative to formaldehyde-based wood adhesives

Wood products are extensively used to make furniture items and construction materials; however, the majority contain formaldehyde-based adhesives that raise serious health concerns. Here, we report a formaldehyde-free adhesive formulation comprised of two high-volume biorefinery biproducts, namely K...

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Bibliographic Details
Published in:Green chemistry : an international journal and green chemistry resource : GC 2018, Vol.20 (7), p.1459-1466
Main Authors: Li, Russell Jingxian, Gutierrez, Jose, Chung, Yi-Lin, Frank, Curtis W., Billington, Sarah L., Sattely, Elizabeth S.
Format: Article
Language:English
Subjects:
Adhesion
Adhesive bonding
Adhesives
Aldehydes
Biodiesel fuels
Biofuels
Biorefineries
Carcinogens
Chemical analysis
Chemical bonds
Construction materials
Crosslinking
Curing
Epoxy resins
Failure rates
Formaldehyde
Formaldehyde resins
Furniture
Glycerol
Green chemistry
Hydroxyl groups
Lignin
Mechanical properties
Mechanical tests
Polymers
Pulp
Pulp & paper industry
Resins
Shear stress
Wood
Wood products
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Summary:Wood products are extensively used to make furniture items and construction materials; however, the majority contain formaldehyde-based adhesives that raise serious health concerns. Here, we report a formaldehyde-free adhesive formulation comprised of two high-volume biorefinery biproducts, namely Kraft lignin (pulp and paper) and glycerol (biodiesel), and its adhesion properties as determined by ultimate shear stress as well as wood failure rates. We show that this lignin-based resin displays the same desirable characteristics as formaldehyde-based resins including water-tolerance, fast curing, and comparable adhesion performance. Chemical analysis indicates that resin curing occurs uncatalyzed via formation of ether bonds between lignin hydroxyl groups and the glycerol-derived crosslinker epoxide. We also show that different lignin and crosslinker feedstocks can be used in the formulation, in some cases with water as a cosolvent, to generate a set of lignin-derived resins with similar properties and mechanical strength. In contrast to the majority of formaldehyde-free adhesives, this lignin-epoxy formulation does not require the use of caustic base and known carcinogens. Furthermore, we demonstrate through mechanical testing and attention to processing conditions that this lignin-based resin has the potential to be a viable alternative to widely used formaldehyde resins.
ISSN:1463-9262
1463-9270
DOI:10.1039/C7GC03026F