Experimental Study on Single Fiber Tensile Properties of Sisal Fibers Using a Digital Image Correlation Method as a Strain Measurement

Figures & data

Figure 1. Diameter measurements of sisal fiber using LSM.

Figure 2. Determining CSA of the fiber using ImageJ software.

Figure 3. Specimen preparation for single fiber tensile testing.

Figure 4. Setup of single fiber tensile testing according to ASTM C1557–03 (a): universal testing machine, (b): detail of clamps and (c): specimen gripped with clamps.

Figure 5. (a) Single fiber tensile testing, and (b) image data processing using limess key and vic-2D software.

Figure 6. Microstructures of sisal fiber using SEM at magnifications of (a): 500× and (b): 2000 × .

Table 1. Densities of the various sisal fiber types using helium gas pycnometer.

Sample fiber type, fiber length	Weight [g]	Mean Pressures [Pa]		Density [g/cm3]	Standard deviation
		P1	P2
Retted, 10 mm Unretted, 10 mm Retted, 5 mm Unretted, 5 mm Milled powder	1.23 1.40 2.24 2.16 3.84	124.24 × 10^3 124.18 × 10^3 124.45 × 10^3 125.07 × 10^3 124.18 × 10^3	36.75 × 10^3 36.82 × 10^3 37.44 × 10^3 37.58 × 10^3 38.47 × 10^3	1.32 1.37 1.41 1.42 1.45	0.010 0.004 0.005 0.007 0.002

Figure 7. Diameter histograms of (a) water retted fibers by calculation, (b) water retted fibers by measurement, (c) unretted fibers by calculation and (d) unretted fibers by measurement.

Figure 8. Images of CSSs of sisal fibers captured by LSM.

Figure 9. Tensile strengths of water retted and unretted sisal fibers.

Table 2. Summary of ANOVA analysis for tensile strength of water-retted and unretted fibers.

Summary of tensile strength [MPa]		Fiber diameter measurement
		Calculated		Measured
Water-retted	Average	678.5		511.7
	Variance	8806.2		26337.9
Unretted	Average	717.9		547.0
	Variance	11469.6		37322.2
ANOVA	Source of variation	F-value	F critical value		P-value
	Water retting	4.2	3.9		0.043
	Diameter measurement	16.4	4.0		0.001

Figure 10. Digital image correlation retrospective through image data processing.

Figure 11. Strains at failure of water retted and unretted sisal fibers.

Table 3. Summary of ANOVA analysis for tensile strain of water-retted and unretted fibers.

Summary strain at failure [%]		Measurement methods
		Direct		DIC
Unretted	Average	2.19		1.54
	Variance	0.10		0.05
Retted	Average	3.08		2.01
	Variance	0.56		0.22
ANOVA	Source of variation	F-value	F critical value		P-value
	Water retting	29.29	4.05		0.002
	Measurement method	65.61	4.05		0.000

Figure 12. Elastic moduli of water retted and unretted sisal fibers.

Table 4. Summary of ANOVA analysis for elastic modulus of water-retted and unretted fibers.

Summary modulus of elasticity [GPa]		Measurement methods
		Direct		DIC
Unretted	Average	44.62		48.33
	Variance	24.12		39.47
Retted	Average	27.92		34.03
	Variance	55.60		52.76
ANOVA	Source of variation	F-value	F critical value		P-value
	Water retting	83.93	4.05		0.000
	Measurement method	5.19	4.05		0.027

Table 5. Obtained mechanical properties of the sisal fiber with respect to the results reported by previous studies.

Density [g/cm^3]	Tensile strength [MPa]	Elastic modulus [GPa]	Strain at failure [%]	Reference
1.45 1.50 1.40 1.31 1.42 1.33 1.39	718 606 555 297 354 650 584	48 16 16 18 13 38 24	1.5 2.3 3.2 2.5 4.5	(*** Results of this study ***) (Gupta and Singh 2018) (Mohapatra and Kar 2019) (Mydin 2022) (Ndoumou et al. 2022) (Veerasimman et al. 2022) (Neto et al. 2019)

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Data availability statement

The data used to support the findings of this study are included within the article.