Cellulosic fibres characterisation

AUi AUiuthali, A., Low, I. M., Dmig, C. Characterisation of the water absorption, mechanical and thermal properties of recycled cellulose fibre reinforced vinyl-ester eco-nanocomposites. Composites Part B - Eng. 43 (2012) 2772-2781. 

Belgacem M.N., Gandini A., Natural Fibre-Surface Modification and Characterisation, in Cellulose Fibre Reinforced Polymer Composites (Eds. Sabu T. and Pothan L.), Old City Publishing, 2007. Chapter 3... 

Gar side and Wyeth [30] have used Fourier transform infrared spectroscopy to characterise cellulose fibres such as jute, sisal, and cotton. The technique has also been used to determine... 

Thermochromatography is useful in studying flame-resistant materials, e.g., cellulose fibres [122]. Phosphorus-containing antipyrenes increase the amount of water present in the degradation products, which, in turn, increases flame resistance of a polymer. The amount and composition of the burning products should also be taken into account in characterising the flame resistance of cellulose fibres [123]. In the thermochromatograms... 

Most fibres made from regenerated cellulose such as viscose, lyocell, and Celsol are characterised by stiffness as well as a fuzzy and uneven surface that makes fabrics susceptible to pilling, even over a short period of use. In order to modify the surface properties of cellulosic fibres and fabrics and to improve their quality biotechnological approaches based on specialised enzymes are widely used. Finishing processes, employing cellulases and xylanases, can replace a number of mechanical and chemical operations, which have been applied until now to improve comfort and quality of fibres and textiles. The principle of enzyme action in the finishing process is controlled hydrolysis of cellulose, in which impurities and fuzz are removed from the surface of fibres, without decreasing their mechanical tenacity or the elasticity of the fabric. 

Parsons, D., Waring, M. J. (2001). Physico-chemical characterisation of carhoxylated spun cellulose fibres. Biomaterials, 22, 903—912. 

Garside and Wyeth [60] have used Fourier transform infrared spectroscopy to characterise cellulose fibres such as jute, sisal, and cotton. The technique has also been used to determine low levels of polyvinyl pyrrolidinone in polysulfone [61]. Weiss and co-workers [62] used Fourier transform infrared microspectroscopy in the study of organic and inorganic phases of an injectable hydroxypropylmethylcellulose-calcium phosphate composite for bone and dental surgery. 

TXRF has also been used for the characterisation of single, colourless textile fibres (polyesters, modified cellulose and wool), yielding a fingerprint trace-element pattern, suitable for forensic purposes [276,277], Sample preparation involved dissolution/predigestion in HN03 and matrix removal (O2 cold plasma). 

Notwithstanding this great variety of mechanical properties the deformation curves of fibres of linear polymers in the glassy state show a great similarity. Typical stress-strain curves of poly(ethylene terephthalate) (PET), cellulose II and poly(p-phenylene terephtha-lamide (PpPTA) are shown in Fig. 13.89. All curves consist of a nearly straight section up to the yield strain between 0.5 and 2.5%, a short yield range characterised by a decrease of the slope, followed by a more or less concave section almost up to fracture. Also the sonic modulus versus strain curves of these fibres are very similar (see Fig. 13.90). Apart from a small shoulder below the yield point for the medium- or low-oriented fibres, the sonic modulus is an increasing, almost linear function of the strain. 

The section ends with some comments on fracture of biological fibres. These fibres are characterised by a hierarchical structural design with length scales ranging from molecular to macroscopic. Clearly, detailed quantitative models for prediction of tensile strength of biological fibres are far from being available. However, some trends in connection with cellulose and keratin fibres are briefly discussed. 

For the common textile uses, fibres are characterised by flexibility, fineness and a high ratio of length to width (McIntyre and Daniels, 1995), but, they must also have an intermediate extensibility. Most have at least partially recoverable extensions up to typical break extensions of 7 to 50%, much higher than for brittle solids or the yield extension of elastic-plastic materials and much lower than for elastomers. Such properties are achieved by partially oriented, partially crystalline polymers, and are almost completely satisfied by six chemical types cellulose, protein, polyamide, polyester, polyacrylonitrile and polypropylene. 

Microbial synthesis of ceUulosic fibres affords the opportunity of obtaining products with unique properties suitable for practical application in medicine and the electronics industry. For synthesis of modified bacterial cellulose, the Acetobacter subsp. strains have been applied. The selection of suitable polyaminosaccharide modifiers allows the production of bacterial cellulose characterised by valuable mechanical, electro-acoustic and biological properties. Practical applications of this ceUulosic composite material for manufacture of novel wound-heaUng dressings as well as diaphragms for loudspeakers have been tested. ... 

The application of IR spectroscopy with respect to the characterisation of cellulosic (plant) fibres is demonstrated. The ability to characterise fibres is of importance to textile conservators, as this information aids in the determination of the age and origin of the artefact from which they are taken, and may influence the choice of treatment. The fibres under examination are taken largely from the bast group (flax, hemp, jute and ramie) in addition, sisal and cotton are compared. FT-IR microspectroscopy and ATR techniques are employed. To complement the conventional use of these methods, the inherent polarisation effects of the equipment are exploited to record polarised IR spectra. Jute, sisal and cotton are readily differentiated, but flax, hemp and ramie prove more difficult to distinguish. Peak ratio techniques are apphed in the latter case. 2 refs. 

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