The effect of moisture on the modulus of elasticity of several representative individual cellulosic fibers

Abstract

Understanding the effect of moisture absorption on the mechanical properties of fibers at cellular level is key important to the application of natural fibers in reinforcement composites. This study focused on the variation of the modulus of elasticity (MOE) of several representative individual cellulosic fibers (bamboo, Chinese fir, ramie and Kevlar) under different relative humidity condition (RH: 40 %, 70 %, 90 %), dedicating for the screening of appropriate candidates of fibers used in outdoors. A special custom-designed microtester (SF-I) with the micro humidity control box was devised in order to observe stress-strain behavior of fibers under different humidity condition. Among the fibers investigated, ramie fiber presented the most sensitive to the humidity, Chinese fir and bamboo fiber was followed, and Kevlar fiber showed the bluntest to moisture variation since it belonged to artificial fiber. Compared with the fibers tested at RH of 40 %, the MOE of Bamboo, Chinese fir, Ramie fibers increased at RH 70 %, and decreased at RH 90 %, respectively. The optimal tensile properties were observed for the bamboo fiber among tested single plant fibers, with a MOE value of 26.3-30.7 GPa, and RH of 70-80 % was deduced for obtaining the highest value of MOE under various humidity testing condition.

Characterization and Research on Mechanical Properties of Bamboo Plastic Composites

“…The tensile property of BPF is presented in Table 3, the strength and the elastic modulus were 508.49 MPa and 6.73 GPa, respectively, while the elongation was 7.44%. These results were lower than that previously reported for bamboo fiber [28]. This may be due to the main constituents of bamboo cell wall being different, the contents of cellulose, hemicelluloses and lignin, which provide the specific mechanical properties and ultimately affect the properties of the BPF [27].…”

Effects of Fiber Surface Grafting with Nano-Clay on the Hydrothermal Ageing Behaviors of Flax Fiber/Epoxy Composite Plates

“…The tensile modulus retention rates of C, S and O were 30.7%, 32.9%, and 41.1%. After the water molecules enter flax fibers, because water molecules can exist in the amorphous structure [8,9], it makes the amorphous structure soften, resulting in a decrease in the modulus of the fiber. Another reason for the decrease in the modulus of the wet sample can be explained by the weakening of the cellulose structure of the natural fiber by the water molecules in the cellulose network structure, where water acts as a plasticizer and allows the cellulose molecules to move freely.…”

“…Cellulose, called micro fibrils, is wrapped by hemicelluloses and lignin, and glued together or linked by hydrogen bonds [7]. Crystalline cellulose cannot store water, but water molecules can store them inside the amorphous hemicellulose and lignin [8,9]. In addition, flax fiber cells contain cell cavities that can store water.…”

Effect of laminated structure design on physical and mechanical properties of laminated bamboo sliver lumber

“…As one of the strongest and fastest-growing plants, bamboo has received increasing attention as an alternative raw material to wood due to its rapid growth rate (just two to five years per cycle), sustainable utilization (i.e., the bamboo culm can be harvested multiple times from a single planting), high specific strength, and stiffness (two to three times when compared to wood), superior toughness, and surface hardness (Liese 1987;Jiang 2007;Xian et al 2015). It has been processed into different forms for decades, and corresponding composites have been manufactured as both non-structural and structural material (Chung and Yu 2002;Albermani et al 2007;Xiao et al 2009;Deng et al 2014a, b).…”