Shear strain and microscopic characterization of a bamboo bonding interface with poly(vinyl alcohol) modified phenol–formaldehyde resin

Abstract

The study of the shear strain distribution at the bonding interface helped us to understand the bamboo bonding interface response mechanisms to solve problems of ply bamboo deformation or bonding failure. The shear strain distribution across a twoply bamboo sheet bonded with a ductile phenol-formaldehyde resin (PF) modified by poly(vinyl alcohol) (PVA) was measured by means of electronic speckle pattern interferometry, along with tensile strength measurements to prove the shear stain distribution on a macroscopic scale. This research effectively combined macroscopic mechanical properties with microcosmic interfacial mechanical properties. The shear strength and shear strain results showed that PF modified with 20% PVA performed better than common PF and PF modified with 5 and 10% PVA. Microscopic fluorescent characterization of the bonding interface also provided evidence that a new bonding mechanism was adequate for bamboo bonding under the ductile PF modified with 20% PVA. Moreover, we suppose that the results of this study will help in the choice of bamboo-specific adhesives under different strain conditions.

Fluorescence microscopy characterization of the bonding interface of scrimbers made of alkali-treated finely fluffed poplar veneers

“…Figure 5 shows the distribution of the PF resin on the bonding interface of the scrimbers. The average penetration depth (AP) and the effective penetration depth (EP) are two important indexes to assess the permeability of the adhesive at the wood bonding interface (Guan et al 2013;Qin et al 2015). Meanwhile, the average glueline thickness was also measured in this study.…”

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

“…On the other hand, bamboo is innately lacking in transverse structure like wood rays, which is not conductive to the flow of adhesives in bamboo. Guan et al characterized the penetration depth of PF resins and poly(vinyl alcohol) modified PF resins in bamboo by using fluorescence microscopy [9]. However, this observation remained at the cellular level.…”

Assessing the tensile shear strength and interfacial bonding mechanism of poplar plywood with high-density polyethylene films as adhesive

“…To facilitate adequate mechanical interlocking, the adhesive must penetrate the wood before it is cured. Traditional wood plastic composites take wood powders or fibers as raw materials, and many authors have reported results for the penetration of adhesives (Gavrilovic-Grmusa et al 2012a,b, 2016Guan et al 2013). However, in such composites the wood unit is tiny and does not have its complete structure, so it is poorly suited to research concerning the impregnation path of resins in wood (Li et al 2013;Sheshmani et al 2013;Shamsul and Srivastava 2016;Ye et al 2016).…”