Figure 7

Orientation parameters vs. modulus of toughness. (a) Hermans orientation parameter and (b) orientation index plotted against the modulus of toughness. Degrees of orientation reached in this work (filled circles) were very similar to those of actively oriented fibers (empty circles) and films (empty squares) reported in the literature^9,12,13,14. Note that the films by Sehaqui et al.²¹ were oriented by drawing before drying whereas those by Henriksson et al.³¹ were not drawn. Additionally, the shown values for orientation parameters of films are for the in-plane orientation. Both Hermans orientation and orientation index are plotted because both the values are not available for all relevant works. (c) and (d) Modulus of toughness vs. Young’s modulus for natural cellulosic fibers (empty squares and empty stars)^43,44, regenerated cellulose based fibers (empty triangles)⁴⁷, reported CNF based fibers from literature^{6,17,19,20,21,31,32} (empty circles) and this work (filled circles). Materials are numbered in order of decreasing toughness value.