Fractal Dimensions of Cell Wall in Growing Cotton Fibers

Michael Ioelovich

doi:10.3390/fractalfract4010006

Abstract

In this research, fractal properties of a cell wall in growing cotton fibers were studied. It was found that dependences of specific pore volume (P) and apparent density (ρ) on the scale factor, F = H/h, can be expressed by power-law equations: P = Po F(Dv−E) and ρ = ρo F(E−Dρ), where h is minimum thickness of the microfibrilar network in the primary cell wall, H is total thickness of cell wall in growing cotton, Dv = 2.556 and Dρ = 2.988 are fractal dimensions. From the obtained results it follows that microfibrilar network of the primary cell wall in immature fibers is loose and disordered, and therefore it has an increased pore volume (Po = 0.037 cm3/g) and low density (ρo = 1.47 g/cm3). With enhance days post anthesis of growing cotton fibers, the wall thickness and density increase, while the pore volume decreases, until dense structure of completely mature fibers is formed with maximum density (1.54 g/cm3) and minimum pore volume (0.006 cm3/g). The fractal dimension for specific pore volume, Dv = 2.556, evidences the mixed surface-volume sorption mechanism of sorbate vapor in the pores. On the other hand, the fractal dimension for apparent density, Dρ = 2.988, is very close to Euclidean volume dimension, E = 3, for the three-dimensional space.

Highlights

Cotton is known to be an important source of natural cellulose [1]
Electron microscopy studies showed that the primary cell wall of the fibers consists of microfibrilar network with a thickness (h) of about 0.1 μm, which is embedded in a hydrophobic lipid matrix [5,6]
The studies have shown that dependence of cell wall thickness (H) on days post anthesis (DPA)

Summary

Introduction

Cotton is known to be an important source of natural cellulose [1]. In particular, cotton is a source of long natural textile fibers, while short cotton fibers (linters) and residues (e.g., fluff) are used to produce micro- and nano-cellulose, cellulose derivatives, special paper, and many other products.Cotton cellulose is biosynthesized in living cells—short and thin fibers (seed-hairs), as follows.After flowering cotton flower, a seed boll is formed, in which the seed-hairs, i.e., immature cotton fibers, begin to grow out from these seeds [2]. Cotton is known to be an important source of natural cellulose [1]. Cotton is a source of long natural textile fibers, while short cotton fibers (linters) and residues (e.g., fluff) are used to produce micro- and nano-cellulose, cellulose derivatives, special paper, and many other products. Cotton cellulose is biosynthesized in living cells—short and thin fibers (seed-hairs), as follows. A seed boll is formed, in which the seed-hairs, i.e., immature cotton fibers, begin to grow out from these seeds [2]. The growth and development of cotton fibers take place in two main stages [3,4]. 15–20 days post anthesis (DPA), a thin primary cell wall is biosynthesized; immature fibers lengthen extremely to 25–30 mm due to growth mechanism by stretching without change in thickness of the primary cell wall. Electron microscopy studies showed that the primary cell wall of the fibers consists of microfibrilar network with a thickness (h) of about 0.1 μm, which is embedded in a hydrophobic lipid matrix [5,6]

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Conclusion