Influence of assemble patterns on bonding strength of glued bamboo
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Journal of Wood Science
Open Access
ORIGINAL ARTICLE
Influence of assemble patterns on bonding strength of glued bamboo Yu Zheng1* , Bao‑long Yi2, Ya‑qi Tong1 and Zhen‑zhen Peng1
Abstract As a kind of natural composite material, the outer side of bamboo was quite different from its inner side in micro‑ scopic structure and mechanical properties. In order to research the effect of these differences on bonding strength of glued bamboo, bamboo strips were bonded by three different forms: outer side to outer side, outer side to inner side and inner side to inner side. Shear strength results indicated that the bamboo sample glued by inner side to inner side has the greatest shear strength value, which is 18.35 MPa, and the other two types have similar shear strength values (approximately 14 MPa). In particular, for the sample glued by outer side to inner side, the broken part is always the outer side. The scanning electron microscope (SEM) images indicated that bamboo fiber cells and paren‑ chyma cells have different failure patterns in compression shear test. For bamboo fiber cells, dominant destruction occurred at the interface between the fibers. And for parenchyma cell, fracture occurred on cell wall and broken the parenchyma cell itself. The interface between bamboo fiber cells was very weak, thus parenchyma cell was the major contributor to shear strength of bamboo. The inner side had higher shear strength because it had higher content of parenchyma cells. The SEM image and shear strength curve also indicated that in the early period of shearing process, the deformed parenchyma cells are in a relax status, and until the later period of shearing process, the parenchyma cells begin to contribute to shear strength. Keywords: Nature composite, Glue bamboo, Bonding strength, Parenchyma cells, Fiber cells Introduction Bamboo is a kind of renewable material, and in recent years, it has attracted increasing attention. Because of its fast-growing speed, high strength and high fracture toughness, bamboo has been expected to be a sustainable alternative for traditional construction materials, such as wood, concrete, steel and timber [1–8]. The bamboo culm is mainly composed of bamboo fiber cells and parenchyma cells [9–14]. Bamboo fiber cell is sclerenchymatous and has excellent mechanical properties [15–17]. The parenchyma cell is hollow and exhibit poor performance on mechanical properties [4, 9, 11, 18, 19]. If we treat bamboo as fiber-reinforced composite material, obviously, bamboo fiber is the reinforcement, *Correspondence: [email protected] 1 Beijing Research Institute of Synthetic Crystals Co., Ltd, Beijing 10018, China Full list of author information is available at the end of the article
and parenchyma is the matrix. As a kind of biomass materials, bamboo appears uneven on microscopic structure. The content of bamboo fiber decreases from outer side to inner side (along the radius, as shown in Fig. 1). The outer side of bamboo has higher density of bamboo fiber, thus the outer side often has better mechani
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