Cotton pore structure

Gel-permeation chromatography" is used to compare the pore structure of jute, scoured jute and purified cotton cellulose. Both native and scoured jute have shown greater pore volumes than cotton. The effects of alkali and acid treatment on the mechanical properties of coir fibers are reported." Scanning electron micrographs of the fractured surfaces of the fibers have revealed extensive fibrillation. Tenacity and extension-at-break decrease with chemical treatment and ultraviolet radiation, whereas an increase in initial modulus and crystallinity is observed with alkali treatment. FTIR spectroscopy shows that the major structural changes that occur when coir fibers are heated isothermally in an air oven (at 100, 150 and 200 °C for 1 h) are attributable to oxidation, dehydration and depolymerization of the cellulose component. 

Physical evidence of crosslinking on a microstructural or morphological level can be seen by response of cotton to methacrylate layer expansion (44). Electron photomicrographs of cross sections of uncrosslinked and crosslinked fibers show differences in responses to this agent after sv lling. The uncrosslinked fiber is expanded to show the lamellae and a pore structure (Figure 5). The fiber that had been crosslinked in a convaitional manner, i.e. in the dry state, exhibits a monolithic cross section with no lamellae separation or visible pore structure. 

Formaldehyde cross-linking is used extensively on a commercial basis, and the pore structures of formaldehyde-cottons have been characterized. Formaldehyde cross-linked cellulose appears to have some application as a medium for gel filtration of carbohydrates, and an Escherichia coli lipopolysaccharide cross-linked with glutaraldehyde has been used in the isolation of anti-polysaccharide antibodies. ... 

An important parameter influencing the mode of action of cellulases is the accessibility of the cellulose to the enzymes. The molecular weights of cellulases range between 30 and 80 kDa. A comparison of the size of cellulase (3-8 nm) and the pore size of cotton swollen in water (1-7 nm) shows very clearly that cellulases can penetrate the cellulose to a limited extent only. In addition, the enzyme reaction takes place preferentially on amorphous cellulose because the more compact, crystalline cellulose structures do not offer any space for such macromolecules. Thus - provided of enzyme and process parameters have been selected correctly -cellulases act mainly on the textile surface. In this way interesting effects on cellu-losic fibers can be achieved. 

Russell, E.W. (1938), Measurement of Pore-space and Crumb or Aggregate Structure of Soils. Proc. Third Conf. Cotton Growers-problems, Rothamsted Exp. Stn. 

As melt intrusion proceeds, air is displaced from the porous silicon flake and air bubbles may be evident. Depending on viscosity and the layer thickness, the pores can be completely filled within a couple of minutes. On removal from the melt, any excess on the surface of the flake can be wiped off with filter paper or a cotton swab - slightly wetting these items, first, with a solvent that is known to dissolve the active, minimizes any residual surface excess this is particularly useful when measuring payload, since it is the active that is in the pores, alone, that contributes to the calculation. Flakes are therefore useful as model structures, since information such as how payloads vary with porosity can readily be obtained. Fig. 1. 

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