Visualisation of the fibrillar and pore morphology of cellulosic fibres applying transmission electron microscopy

Abstract

Applying transmission electron microscopy (TEM) on ultra-thin cross-sections of fibres, the main characteristics of the internal morphology of cotton and the main man-made cellulosic fibres (modal, viscose and lyocell) could be visualised. To obtain an appropriate contrast for TEM, isoprene was polymerised into the swollen fibres after a stepwise solvent exchange from water to acetone. The included polymer is stainable with osmium tetraoxide. Significant differences in distribution of pore sizes and pore arrangements in the cellulosic fibres were seen. Cotton showed very small pores in the bulk of the fibre, but drying cracks and flat pores between the sheets of the secondary wall appear as larger pores. Lyocell contains only nanopores in the bulk of the fibre with a slight gradient in pore density, and a very porous skin layer. In viscose and modal, a very wide pore size distribution from nanometer to micrometer size can be seen.

The study of water behaviour in regenerated cellulosic fibres by low-resolution proton NMR

“…Comfort is also associated with the interaction of water with cellulose at the molecular level [5], which induces a strong exothermic sorption response, with an equivalent endothermic response induced as water is evaporated [6,7]. The nanoscale textures created in cellulosic fibres during regeneration have a high liquid holding capacity, as pore spaces are opened between cellulose polymer domains [8][9][10]. The rapid uptake of water into the fibre internal volume is ideal for technical applications where high absorbency is required [11].…”

Morphology of cellulose objects regenerated from cellulose–N-methylmorpholine N-oxide–water solutions

“…Some pores and defects could be also present in the amorphous regions. Abu-Rous et al (2006) showed that Lyocell fibres contain only nanopores in the core of the fibre and a very porous skin layer. Schurz et al (1995) proposed a structural model for fibres spun from cellulose-NMMO-water solutions.…”

Properties of osmanthus fragrance‐loaded chitosan–sodium tripolyphosphate nanoparticles delivered through cotton fabrics

“…Although the treatment decreased the number of nanoparticles on the cotton fabrics, there were still a little bit of nanoparticles dispersed on the surface of the cotton, which was attributed to the chemical structure and framework structure of the cotton fabrics. Holes (50–200 nm) on the surface of the cotton fibers26 could make the nanoparticles penetrate into themselves depending on the osmotic pressures. Besides, cotton was a natural fiber consisting of cellulose with 1,4‐ D ‐glucosepyranose as its repeating units 27.…”