Enhancing and toughening bamboo interfacial bonding strength by reactive hyperbranched polyethyleneimine modified phenol formaldehyde resin adhesive

作者：Jinhui Wang, Ruisong Wang, Xiaoxiao Ji, Chunde Jin, Yutao Yan · 发表于：Journal of Materials Research and Technology · 年份：2023 · DOI：10.1016/j.jmrt.2023.09.176 · 被引用次数：31 · 研究领域：Natural Fiber Reinforced Composites、Bamboo properties and applications、Wood Treatment and Properties

Phenol formaldehyde (PF) resin adhesives are widely used in the production of bamboo-based composites owing to their excellent bonding strength and durability. However, the inherent brittleness of cured PF resin may result in notable stress concentration at the interface between PF resin and bamboo bonding, leading to the generation of cracks. In this study, a hyperbranched compound polyethyleneimine (PEI) with high reaction activity was incorporated into a PF resin adhesive to toughen the adhesive and the bonding interface. And the effects of PEI incorporation on the properties of the adhesive and the bonding performance between PF resin and bamboo were comprehensively investigated. The results showed that introduction of flexible PEI chains could effectively facilitated stress transfer, avoiding stress concentration, thus enabling efficient energy release and play a toughening effect. In addition, PEI could react with PF resin and bamboo components during hot pressing, forming a three-dimensional network structure and enhancing the bonding interface, which was proved by FT-IR and XPS analysis. When 1 wt% PEI was incorporated, the bending strength and Charpy impact toughness of the modified PF resin was significantly increased by 38.88% and 76.02%, respectively, compared with the pure PF resin. While the dry and wet shear strength of the bamboo composite bonded by the PEI modified PF resin were also obviously increased. This study is expected to address the problem of cracki...