Diameter dependence of tensile strength by Weibull analysis: Part I bamboo fiber

Abstract

Fibers stripped of from the bamboo culm by longitudinal cutting are being considered as reinforcement of polymer composites owing to environmental benefits related to their biodegradable and renewable characteristics. The manual cutting process allows bamboo fibers with different diameters to be extracted from the culm. Since a lignocellulosic fiber usually presents tensile strength dependence with its diameter, this possibility was investigated on bamboo fibers by means of the Weibull statistical analysis. It was found that the smaller the fiber diameter, the greater the tensile strength. Fracture observation of ruptured bamboo fibers by scanning electron microscopy, identified possible mechanisms associated with this inverse strength/diameter correlation.

Natural Lignocellulosic Fibers as Engineering Materials—An Overview

“…The already mentioned recent works [10][11][12][13][14][15][16][17][18][19] on the tensile strength variation with the LCF equivalent diameter showed a consistent inverse correlation similar to what was earlier reported on pineapple. [4,8] Consequently, very thin diameter LCFs could eventually be selected with relatively high strength.…”

“…[10][11][12][13][14][15][16][17][18][19] The statistical distribution of diameters was based on 100 randomly picked fibers from the lots. For each type of fiber overviewed in the PW, histograms corresponding to the frequency of diameter distribution were obtained [10][11][12][13][14][15][16][17][18][19] and reproduced in Figure 3. Diameters and cross-sectional areas along the fiber length were evaluated by means of profile projector measurements.…”

“…[8] For palmirah fibers, the strength and the elongation decreased with the test length. [9] Recent works [10][11][12][13][14][15][16][17][18][19] have shown that not only pineapple but also many LCF species display an inverse correlation between the fiber diameter and its tensile strength. This appears to be a common feature to all fibers owing to the role played by microstructural defects and an intrinsic statistical distribution of microfibril strength.…”

“…This appears to be a common feature to all fibers owing to the role played by microstructural defects and an intrinsic statistical distribution of microfibril strength. [12][13][14][15][16] As a consequence of the inverse correlation, tensile strengths comparable to or even above those attained by conventional high-strength lowalloy steels were exhibited by several LCFs with the additional advantage of a much lower density. Previous works [4,[20][21][22] reported on relatively high tensile strengths for a restricted number of LCFs; however, no systematic investigation was attempted to characterize a location or field of properties associated with a corresponding class of engineering material.…”

Interfacial Characterization by Pull-Out Test of Bamboo Fibers Embedded in Poly(Lactic Acid)

“…The F max values in Figure 6 are spread over a range of equivalent diameters from about 250 µm to almost one millimeter, but regular tests were obtained only for samples processed with fibers having a diameter less than 500 µm, whatever the value of L emb . As a matter of fact, Da Costa et al [41] already observed that, when performing tensile tests on bamboo fibers with the aim of Weibull analysis, thinner fibers showed a more uniform fracture associated with lesser fibrils, while fibers with larger diameters would display a relatively non-uniform fracture with participation of more fibrils. Statistically, the probability that one of the many fibrils of the thicker bamboo fiber would prematurely break and then act as a flaw to cause the fiber rupture at a lower stress is higher, when compared to the thinner fiber.…”