Novel Highly Branched Polymer Wood Adhesive Resin

Abstract

We propose a new idea for facile and green synthesis of urea-based highly branched polymers (HBPs) using polyamines and urea via deamination. More importantly, our strategy is to directly use the synthesized HBPs to construct plywood. The HBPs would be further condensed and solidified during the hot pressing process, resulting in the aldehyde-free wood adhesive with a high bonding performance. In this work, water-soluble HBPs were synthesized by one-pot and one-step strategy via polycondensations between urea (U) and tris(2-aminoethyl)amine (TAEA), with no solvents and catalysts used, as well as purification was also avoided. Here, the TAEA was selected as a model compound of polyamine. Urea was used in this synthesis because of it is one of the cheapest chemicals. Structure characterizations show that the polymers contain both terminal amine and urea groups and their relative contents varied with respect to different monomer ratios. For the first time, the performances of the HBPs water solutions directly used as wood adhesive resins were investigated. The resins showed excellent water resistance, as the bonding strengths were still greater than 1.8 MPa after 7 h boiling water soaking, indicating that the cured resins that consist of polyurea and biuret linkages are quite stable toward hydrolysis. In a wide range of monomer ratio of 1.5−2.5, the bonding performance of the resins did not vary significantly. This study extended the potential applications of HBPs to the wood industry and provides a possible and potential solution to the formaldehyde emission problem of the wood-based products. The advantages of HBP resins over traditional wood adhesives in the synthesis and applications make large-scale application of such resins practical and attractive.

From Wastes to Functions: A New Soybean Meal and Bark-Based Adhesive

“…Low solids content and high viscosity are typical limitations associated with soy-based adhesives which negatively influence the flowability and gluability of the adhesive to decease their range of applications. , The solids content of the developed adhesives is given in Table . The solids content of SM-only adhesive is 26.92%, and this means that more water has to be evaporated from the adhesive and the wood veneer during the plywood manufacturing process, which lowers the production efficiency and bonding quality.…”

Developing High-Performance Cellulose-Based Wood Adhesive with a Cross-Linked Network

“…The enhancement of adhesive viscosity via introducing hyperbranched polymers has been the concern of numerous research studies by virtue of its highly branched 3D structure, low chain entanglement, versatile terminal functional groups, and brief synthetic route for the past decades. − Beyond functioning in ensuring low viscosity, fine solubility, elevated reactivity, increased cross-linking sites, reduced formaldehyde emission level, − additionally, free volume and internal cavities formed when the hyperbranched polymer is cross-linked with the target molecular structure will induce the cavitation effect, which can absorb energy under stress, so making the material more tough . Plenty of studies, including our previous work, , have demonstrated that the application of hyperbranched polymers in wood adhesives is feasible; herein, it is expected to be used to modify cellulose-based adhesives.…”

“…42−44 Beyond functioning in ensuring low viscosity, fine solubility, elevated reactivity, increased cross-linking sites, reduced formaldehyde emission level, 45−47 additionally, free volume and internal cavities formed when the hyperbranched polymer is cross-linked with the target molecular structure will induce the cavitation effect, which can absorb energy under stress, so making the material more tough. 48 Plenty of studies, including our previous work, 45,49 have demonstrated that the application of hyperbranched polymers in wood adhesives is feasible; herein, it is expected to be used to modify cellulose-based adhesives.…”

Green Wood Adhesives from One-Pot Coacervation of Folic Acid and Branched Poly(ethylene imine)

“…Wood-based products, such as plywood, particleboard, fiberboard, and oriented strand board, are closely related to the everyday life of human beings. For example, furniture is used in every house and offices, and most furniture is an ensemble of different pieces of wood joined together with adhesives. , However, most of the adhesives used in wood products like furniture are formaldehyde-based chemicals, such as phenolic resin, urea formaldehyde resin, and melamine urea formaldehyde resin, which would release formaldehyde and other volatile organic compounds during the process of use. − Because formaldehyde is a human carcinogen, people have to make a lot of efforts to get rid of formaldehyde emitted by furniture . Since formaldehyde release could be a life-long process for some furniture, the formaldehyde-based adhesives have loaded unneglectable harms to human beings.…”

“…For example, furniture is used in every house and offices, and most furniture is an ensemble of different pieces of wood joined together with adhesives. 1,2 However, most of the adhesives used in wood products like furniture are formaldehyde-based chemicals, such as phenolic resin, urea formaldehyde resin, and melamine urea formaldehyde resin, which would release formaldehyde and other volatile organic compounds during the process of use. 3−5 Because formaldehyde is a human carcinogen, people have to make a lot of efforts to get rid of formaldehyde emitted by furniture.…”