PSI - Issue 14

Ramesh Babu Adusumalli et al. / Procedia Structural Integrity 14 (2019) 150–157 R.B. Adusumalli / Structural Integrity Procedia 00 (2018) 000 – 000

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Table 1. Mechanical properties of single fibres. Indentation modulus is a longitudinal modulus obtained by indenting on fibre cross-sections Fibre type Indentation modulus (GPa) Tensile modulus ( GPa ) Tensile strength ( MPa ) Tensile elongation ( % ) Flax (Bast cellulose fibre) 12-23 28-40 500-900 1.4 Pulp (bleached cellulose fibre)

10-13 11-17 8-11 4-7 10-20 70-75

3-6 20-25 8-12 2-4 65-90

200-350 420-520 400-420

4-8 6-7 15-20

Lyocell (man made cellulose fibre) Viscose (man made cellulose fibre)

Hair (single keratin fibre) Kevlar (Polyaramid fibre)

200-350 2800-3000

40-50 1.5-3.5

E-glass (amorphous ceramic fibre)

70

2900

3-4

Fig. 6. SEM fractographs of single hair fibres subjected to tensile testing. Fracture pattern are split fracture (a) smooth fracture (b) and step fracture (c & d).

Fig. 7. Weibull distribution of single fibre tensile strength values. Note the lowest values of Weibull modulus (β) for natural fibres such as pulp (β=1), flax (β=2.1) and hair (β=3.4) compared to synthetic fibre such as lyocell (β=7). Lower values of β indicates broader distribution of strength.

SEM fractography revealed brittle fracture (smooth) for pulp fibres and different fracture patterns (smooth, step and split) for hair fibre as shown in Fig. 6. Smooth fracture is evident in both cellulose and keratin fibres because of the