Identification of New Textile Fibers
The differences in composition such as macrostructure and microstructure between new fibers such as lyocell fibre, modal fibre, soybean protein fiber, bamboo fibre, milk protein fibre and chitin fibre must result in discrepancies in macroscopic features, physical and chemical properties, which can be used to distinguish different fibers. Some efficient methods of identification the six new textile fibers listed above are presented.
Identification of Lyocell Fiber
The nature or generic type of a cellulosic material may be determined by a burning test and then the longitudinal feature may be observed by micro-scopic examination, referring to the information from fibres such as modal, bamboo, chitin, cotton and regular viscose fibers. Sodium hypochlorite may be used as a solvent to investigate the dissolution behaviour further. In addition, a tensile test may be carried out to find out the tenacity of the fibre, as the tenacity of lyocell fibre is the highest among the cellulosic fibres.
Identification of Modal Fiber
The nature or generic type of a cellulosic material may be determined by a burning test and then the longitudinal feature may be observed by micro-scopic examination, referring to the information from fibres such as modal, bamboo, chitin, cotton and regular viscose fibres. In addition, the modal fibre cross-section may be observed by microscope taking the reference as bamboo fibre and regular viscose. Subsequently, 75% sulfuric acid may be used as a solvent to observe the solubility. Tensile and wet elongation tests may be performed to determine the tenacity.
Identification of Soybean Protein Fiber
Firstly, the nature or generic type of a protein fibre may be determined by a burning test. Then, an iodine–potassium iodide staining test may be performed to exclude wool and silk. A solution of boiling 5% sodium hydrox- ide may be used as a solvent to find out the dissolution behaviour: soybean protein fibre does not dissolve, milk fibres swell and become moist, and chitin fibre dissolves. Finally, boiling dimethyl formamide (DMF) may be used as a solvent to examine the protein fibre further.
Identification of Bamboo Fiber
Firstly, the nature or generic type of a cellulosic material may be determined by a burning test and then the longitudinal feature may be observed by microscopic examination, referring to the information from fibres such as modal, bamboo, chitin, cotton and regular viscose fibres. Subsequently, 37% hydrochloric acid may be used as a solvent to observe the solubility at normal temperature: modal fibre dissolves quickly, while regular viscose dissolves slowly and bamboo fibre dissolves partially. Finally, a density test may be used (using a density grading column) to determine the density. The density of bamboo fibre is lower than those of regular viscose, lyocell, modal and cotton fibres.
Identification of Milk Protein Fiber
Firstly, the nature or generic type of a protein fibre may be determined by a burning test. Then an iodine–potassium iodide staining test may be performed to exclude wool and silk. Microscopic observation may help reveal surface features. While the surface of milk fibres appears smooth and nonmicroporous, soybean protein fibres are not smooth and show random microporous surfaces with a spot-welding effect. Subsequently, boiling dimethyl formamide (DMF) may be used as a solvent to find out the dissolution behaviour. Milk fibers moisten and swell, whereas other protein fibres such as wool, silk, chitin and soybean protein fibres exhibit no changes.
Identification of Chitin Fiber
Firstly, a burning test may be used to observe the fibre’s burning behaviour. Chitin fibre does not melt or shrink upon being subjected to a flame, but it burns rapidly like a cellulosic fibre with the odour of burning a protein fibre.
The distinguishing features of chitin compared to other fibers are that it burns rapidly to black while keeping its original shape, the ash produced being greyish in colour and easily crumbled. After initially observing its burning behaviour by a burning test, the surface may be observed using a microscope. The surface of the fibre is characterized by small openings and cracks. An iodine–potassium iodide test may reveal important information: while in a wet state, lyocell, modal, bamboo and regular viscose fibres look alike, but upon drying, iodine on the chitin fibre sublimes easily, resulting in a blackish-blue to red-brown colour. As in other protein fibres, 5% boiling sodium hydroxide may be used as a solvent to observe the solubility. Chitin fibre dissolves in this solvent. Alternatively, 88% boiling formic acid may be used: here only chitin fibre dissolves, whereas all other fibres show no dissolution.
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
