Multi-scale characterization of bamboo bonding interfaces with phenol-formaldehyde resin of different molecular weight to study the bonding mechanism

Abstract

<jats:p>Understanding the bonding mechanism of the interfacial region between bamboo and adhesives is essential for accelerating the development of improved adhesives for advanced bamboo-based materials. In this study, Br-labelled phenol-formaldehyde (PF) resins with four different molecular weights (MWs) were used to make bamboo–adhesive interfaces for tracing the adhesives in bamboo. Ultra-depth-of-field microscopy and scanning electron microscopy in conjunction with energy dispersion spectrometry were used to access the distribution and penetration of resin in the bamboo polymer. Fourier transform infrared images and solid-state cross-polarization/magic angle spinning nuclear magnetic resonance spectra were used to access the molecular-scale interactions between PF resins and bamboo cell walls. The results showed that the PF resins with high MW infiltrated into the lumina of damaged bamboo cells near the bondline to form glue nails, while those with low MW penetrated into the bamboo cell wall to form nanomechanical interlocking. Chemical bonds and secondary forces such as polar forces and hydrogen bonds were generated between bamboo and PF resin. Finally, the twice-adhesive dispensing method combining low-MW resins with high-MW resins was used to improve the bonding strength of the interface.</jats:p>

Hydrodeoxygenation of condensed lignins followed by acid-mediated methylolation enables preparation of lignin-based wood adhesives

“…The image at the glue line region of the slice was recorded with a Spectrum Spotlight 400 FTIR microscope connected to a Spectrum FTIR Frontier spectrometer (PerkinElmer Inc., Shelton, CT, USA) with a transmission mode. 24 Measurements provided a pixel resolution of 6.25 × 6.25 μm 2 . The FTIR absorption image at a size of 2200 × 2200 μm 2 was calculated from the absorbance at a wavenumber of 1597 cm −1 after atmospheric compensation.…”

Processing composites reinforced with wood fibers into an ultra‐strong structural materials

“…The detailed synthesis of Br-labeled PR resin has been published in the literature. [19] 2.4 | Characterization…”

Enhanced bamboo interfacial bonding performance on the basis of toughening phenol formaldehyde resin by flour

“…However, currently most of bamboo‐based composites are inseparable from the bonding effect of adhesives, and effective interface bonding strength is the key to ensuring the excellent performance of these composite materials. [ 10 ]…”

“…However, currently most of bamboo-based composites are inseparable from the bonding effect of adhesives, and effective interface bonding strength is the key to ensuring the excellent performance of these composite materials. [10] Phenol formaldehyde (PF) resin, due to its excellent bonding strength, heat resistance, water resistance, and abrasion resistance, [11,12] currently is considered as one of the most commonly used adhesives in wood and bamboo bonding. [13][14][15] .…”