Identifying soya bean protein fibres

These fibres have few surface features and a circular cross-section - see Fig. 13.12(a) and (b). However, these features cannot be used as the sole basis for identification. In common with other man-made fibres, such characteristics may be influenced by the temperature of extrusion, the viscosity of the spinning solution or pressure exerted by processing equipment, depending upon the degree of plasticity in different stages of production. Fine marks and striations may therefore be visible on the surface of all such fibres.  

Fletcher reports that soya bean fibres responded like wool to chemical and burning tests. Press describes their behaviour in bum tests soya bean protein fibres melt away from the flame before touching the flame and melt and burn in the flame with a smell of burning feathers although they do not combust easily, tending to melt before burning. The black ash is said to be brittle, puffy and easily crushable. 

12 (a) Longitudinal view (x75) of mid-twentieth century soya bean protein fibre. From Harris, M. (1954). Handbook of Textile Fibers. Washington Harris Research Laboratories, 82. (b) Cross-sectional view (x380) of mid-twentieth century soya bean protein fibre. From Harris, M. (1954). Handbook of Textile Fibers. Washington Harris Research Laboratories, 82. 

2 Late twentieth and early twenty-first century fibres 

SPF has irregular striations running longitudinally along the surface which are said to contribute to the fibre s moisture-absorbing properties (Fig. 13.13). 

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