Progress 09/15/01 to 09/30/04
Outputs
This research is to investigate how to convert soy protein to a strong and water resistant wood adhesive, using marine adhesive protein as a model. The marine adhesive protein, a superior adhesive in seawater contains high amounts of phenolic hydroxyl groups (especially catechol moiety), di-sulfur linkages and amino groups. We demonstrated that poly(4-vinylphenol) (a polymer with phenolic hydroxyl groups) could bond maple veneers very strongly in the presence of an amino compound such as 1,6-hexanediamine. We synthesized poly(N-acryloyldopamine) (PAD) and used it as a surrogate of marine adhesives for production of wood composites. PAD The shear strengths of wood composites bonded with PAD increased, rather than decreased, after the wood composites underwent a water-soaking-and-drying treatment. A mixture of PAD and polyethylenimine resulted in much higher shear strengths than PAD alone. The adjacent two phenolic hydroxyl groups in poly(N-acryloyldopamine) play
essential roles in the strong adhesion. Condensed tannins contain the same phenolic functional group; i.e., the catechol moiety, as marine adhesive protein. We found that a mixture of condensed tannins and a polyamine was a strong and water-resistant wood adhesive. We further demonstrated that chitosan (a polymer with amino functional groups), could bond veneer strongly in the presence of a phenolic compound such catechol and an oxidative enzyme laccase. These results suggest that functional groups in a polymer, rather than the polymer backbone, play a crucial role in the strong bonding. With this concept in hand, we grafted a phenolic compound to soy protein through an amide linkage. As expected, plywood bonded with the grafted soy protein has much higher shear strengths than with unmodified soy protein. More impressively, the plywood bonded with the grafted soy protein (12 duplicated measurements) is very water resistant: the shear strengths of the plywood did not decrease after the
plywood was soaked in water for 24 hours and then air-dried in a fume hood for 20 hours. We also grafted cysteamine to soy protein via an amide linkage to increase the free mercapto (-SH) group content in soy protein. Cysteamine-modified soy protein had superior adhesive properties than unmodified soy protein. Our results revealed that introduction of a key functional group in marine adhesive protein to soy protein can convert soy protein to a strong and water-resistant wood adhesive. In other words, change of a single amino acid in soy protein can greatly enhance adhesive properties of soy protein.
Impacts
We have demonstrated that natural adhesion principle found in marine adhesive protein could be applied to development of a strong and water resistant wood adhesive. We are establishing a new adhesion concept for wood adhesives. Based on this new concept, we could develop a formaldehyde-free wood adhesive with competitive properties from a renewable natural resource.
Publications
- Peshkova, S. and K. Li. 2003. Investigation of poly(4-vinylphenol) as a wood adhesive. Wood Fiber Sci. 35(1):41-48.
- Liu, Y. and K. Li. 2004. Modification of soy protein for wood adhesives using mussel protein as a model: The influence of a mercapto group. Macromol. Rapid Commun. (In press).
- Liu, Y. and K. Li. 2002. Chemical modification of soy protein for wood adhesives. Macromol. Rapid Commun. 23(13):739-742.
- Li, K., X. Geng, J. Simonsen and J.J. Karchesy. 2004. Novel wood adhesives from condensed tannins and polyethylenimine. Int. J. Adhesion Adhes. 24(4):327-333.
- Zhang, C., K. Li and J. Simonsen. 2003. A novel wood-binding domain of a wood-plastic coupling agent: development and characterization. J. Appl. Polm. Sci. 89(4):1078-1084.
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Progress 01/01/03 to 12/31/03
Outputs
This research is to investigate how to convert soy protein to a strong and water resistant wood adhesive, using marine adhesive protein as a model. The marine adhesive protein, a superior adhesive in seawater contains high amounts of 3,4-dihydroxylphenylalanine (DOPA) and lysine. Condensed tannins from Douglas fir bark contain the same catechol moiety as that in DOPA. It was found that a combination of condensed tannins and a polyethylenimine was an excellent wood adhesive system. We demonstrated that poly(4-vinylphenol) (a polymer with phenolic hydroxyl groups) could bond maple veneers very strongly in the presence of an amino compound such as 1,6-hexanediamine. We further demonstrated that chitosan (a polymer with amino functional groups), could bond veneer strongly in the presence of a phenolic compound such catechol and an oxidative enzyme laccase. These results suggest that functional groups in a polymer, rather than the polymer backbone, play a crucial role in
the strong bonding. With this concept in hand, we grafted a phenolic compound to soy protein through an amide linkage. As expected, plywood bonded with the grafted soy protein has much higher shear strengths than with unmodified soy protein. More impressively, the plywood bonded with the grafted soy protein (12 duplicated measurements) is very water resistant: the shear strengths of the plywood did not decrease after the plywood was soaked in water for 24 hours and then air-dried in a fume hood for 20 hours. We have thus far demonstrated that modification of a single amino acid in soy protein could dramatically enhance the adhesive ability of the modified soy protein. We have obtained some very exciting results and have basically achieved the objectives proposed in this project. One of the formaldehyde-free wood adhesives resulted from this financial support is heading toward a mill trial.
Impacts
We have demonstrated that natural adhesion principle found in marine adhesive protein could be applied to development of a strong and water resistant wood adhesive. We are establishing a new adhesion concept for wood adhesives. Based on this new concept, we could develop a formaldehyde-free wood adhesive with competitive properties from a renewable natural resource.
Publications
- Li, K., X. Geng, J. Simonsen and J.J. Karchesy. 2003. Novel wood adhesives from condensed tannins and polyethylenimine. Int. J. Adhesion Adhes. (In Press).
- Rogers, J., X. Geng and K. Li. 2003. Soy-based adhesives with 1,3-dichloro-2-propanol as curing agent. Wood Fiber Sci. (In Press).
- Peshkova, S. and K. Li. 2003. Investigation of chitosan-phenolics system as wood adhesives. J. Biotechnol. 102(2):199-207.
- Li, K. and X. Geng. 2003. Investigation of formaldehyde-free wood adhesives from kraft lignin and a polyaminoamide-epichlorohydrin resin. J. Adh. Sci. Technol. (In Press).
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Progress 01/01/02 to 12/31/02
Outputs
This research investigated how to convert soy protein to a strong and water resistant wood adhesive, using marine adhesive protein as a model. The marine adhesive protein, a superior adhesive in seawater contains high amounts of 3,4-dihydroxylphenylalanine and lysine. We demonstrated that poly(4-vinylphenol)(a polymer with phenolic hydroxyl groups) could bond maple veneers very strongly in the presence of an amino compound such as 1,6-hexanediamine. We synthesized poly(N-acryloyldopamine) (PAD) and poly (N-acryloyltyramine) (PAT) and used them as surrogates of marine adhesives for production of wood composites. PAD had much higher adhesive ability than PAT. The adjacent two phenolic hydroxyl groups in poly(N-acryloyldopamine) play essential roles in the strong adhesion. The shear strengths of wood composites bonded with PAD increased, rather than decreased, after the wood composites underwent a water-soaking-and-drying treatment. A mixture of PAD and polyethylenimine
resulted in much higher shear strengths than PAD alone. We further demonstrated that chitosan (a polymer with amino functional groups), could bond veneer strongly in the presence of a phenolic compound such as catechol and an oxidative enzyme laccase. These results suggest that functional groups in a polymer, rather than the polymer backbone, play a crucial role in the strong bonding. With this concept in hand, we grafted a phenolic compound to soy protein through an amide linkage. As expected, plywood bonded with the grafted soy protein has much higher shear strengths than with unmodified soy protein. More impressively, the plywood bonded with the grafted soy protein (122 duplicated measurements) is very water resistant: the shear strengths of the plywood did not decrease after the plywood was soaked in water for 24 hours and then air-dried in a fume hood for 20 hours. Our results revealed that introduction of a key functional group in marine adhesive protein to soy protein can
convert soy protein to a strong and water-resistant wood adhesive. In other words, change of a single amino acid in soy protein can greatly enhance adhesive properties of soy protein. We recently demonstrated that conversion of tyrosine in soy protein to 3,4-dihydroxylphenylalanine greatly enhanced the adhesive properties of the soy protein. We are currently investigating the quantitative contribution of phenolic hydroxyl groups and amino groups to the adhesive properties of soy protein. We are getting some very exciting results and are ahead of schedule.
Impacts
We have demonstrated that the natural adhesion principle found in marine adhesive protein could be applied to development of a strong and water resistant wood adhesive. We are establishing a new adhesion concept for wood adhesives. Based on this new concept, we could develop a formaldehyde-free wood adhesive with competitive properties from a renewable natural resource.
Publications
- Peshkova, S. and K. Li. 2003. Investigation of chitosan-phenolics system as wood adhesives. J. Biotechnol. (In press).
- Peshkova, S. and K. Li. 2003. Investigation of poly(4-vinylphenol) as a wood adhesive. Wood Fiber Sci. 35(1):41-48.
- Zhang, C., K. Li and J. Simonsen. 2003. A novel wood-binding domain for a wood-plastic coupling agent: Development and characterization. J. Appl. Polym. Sci. (In press).
- Liu, Y. and K. Li. 2002. Chemical modification of soy protein for wood adhesives. Macromol. Rapid Commun. 23(13):739-742.
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Progress 01/01/01 to 12/31/01
Outputs
This research is to investigate how to convert soy protein to a strong and water resistant wood adhesive, using marine adhesive protein as a model. The marine adhesive protein, a superior adhesive in seawater contains high amounts of 3,4-dihydroxylphenylalanine and lysine. We demonstrated that poly(4-vinylphenol) (a polymer with phenolic hydroxyl groups) could bond maple veneers very strongly in the presence of an amino compound such as 1,6-hexanediamine. We further demonstrated that chitosan (a polymer with amino functional groups), could bond veneer strongly in the presence of a phenolic compound such as catechol and an oxidative enzyme laccase. These results suggest that functional groups in a polymer, rather than the polymer backbone, play a crucial role in the strong bonding. With this concept in hand, we grafted a phenolic compound to soy protein through an amide linkage. As expected, plywood bonded with the grafted soy protein has much higher shear strengths
than with unmodified soy protein. More impressively, the plywood bonded with the grafted soy protein (12 duplicated measurements) is very water resistant: the shear strengths of the plywood did not decrease after the plywood was soaked in water for 24 hours and then air-dried in a fume hood for 20 hours. We are currently quantifying the contribution of a phenolic hydroxyl group to the shear strength. We are getting some very exciting results and are ahead of the schedule.
Impacts
We have demonstrated that the natural adhesion principle found in marine adhesive protein could be applied to development of a strong and water resistant wood adhesive. We are establishing a new adhesion concept for wood adhesives. Based on this new concept, we could develop a formaldehyde-free wood adhesive with competitive properties from a renewable natural resource.
Publications
- Peshkova, S. and K. Li. 2002. Investigation of poly (4-vinylphenol) as a wood adhesive. Wood Fiber Sci. (Accepted for publication).
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