Volume 5, Issue 2

This paper presents a comparative study of the methods used to determine the technological value or overall quality of cotton fibre. Three existing methods, namely the fibre quality index (FQI), the spinning consistency index (SCI) and the premium-discount index (PDI) have been considered, and a new method has been proposed based on a multiple-criteria decision-making (MCDM) technique. The efficacy of these methods was determined by conducting a rank correlation analysis between the technological values of cotton and yarn strength. It was found that the rank correlation differs widely for the three existing methods. The proposed method of MCDM (multiplicative AHP) could enhance the correlation between the technological value of cotton and yarn strength.

The tensile behaviour of fully degummed filaments of two commercial varieties of silk produced in India, namely mulberry (Bombyx mori) and tasar (Antheraea mylitta), has been investigated in dry and wet state. The tensile properties were correlated with the structures and morphologies of these two varieties of silk. The tenacity and elongation at break of these silks were not significantly different in dry and wet state; however, a slight reduction in initial modulus was noticed in wet state. The stress-strain behaviour of mulberry silk filament was different from that of tasar in that it demonstrated a characteristic yield point, lower modulus and elongation at break twice as high as that of mulberry. The characteristic stress-strain behaviour of theses two varieties of silk was correlated with density, birefringence, orientation index, sonic modulus and amino-acid composition. Poor orientation and less order in tasar are related to the higher percent of bulky groups present in fibroin.

The mechanism of twist insertion to the strand during ring spinning has been studied. The twisting of the strand occurs not only due to the rotation of twisting elements, but also due to the winding of yarn on the package. When the yarn is wound on a stationary cop by gripping and winding the yarn by hand, for every coil of yarn wind one turn of twist to the yarn is inserted. But the same yarn is over-end withdrawn from the cop, and all twists inserted during winding are removed during unwinding. Over-end unwinding rotates the yarn in the opposite direction. Since the yarn from the cop is over-end withdrawn during winding, the spindle speed is taken for calculating the twist in the yarn, whereas the flyer speed is taken for calculating twist in the roving due to the parallel unwinding of roving during spinning.

An experimental design method was used in order to determine the most relevant parameters as well as the crossing effects to be considered in mechanical splicing. This approach was applied in order to establish a statistical model to predict the splicing properties of thick and medium cotton yarns for denim fabrics. This model shows that the change in the value of drafting has no influence on the properties of the mechanical splicing. Moreover, high values of untwisting and low re-twisting values improve those properties. The result proved that in optimal conditions, and in contrast to pneumatic splicing, the yarn linear density has no influence on the properties of splice. Therefore, mechanical splicing may be used for a wide range of yarns.

Carpet waste is of growing concern both to environmentalists and manufacturers pressured by increasing costs of landfill dumping. The challenge for carpet producers is to find ways of minimising their waste or find alternative uses for their unwanted byproducts. This paper builds on an earlier study (Taylor, A.: ‘Novel underlays from carpet waste’, Ph.D. thesis, Bolton Institute, U.K., 2004) where carpet tile wastes have been successfully used to produce underlays for domestic as well as commercial markets. To add value, the acoustic behaviour of these underlays, where granular/fibre mixing ratios, binder concentration and particle size distribution play a major role, has been examined in this study. The results show that it is possible to maximise the impact sound insulation capabilities of these underlays by selective control and adjustment of the above variables. Manufacturing formulation consisting of 60:40 granular/fibre mixture ratio, 60% binder concentration and granule particle size dimensions of <2mm is shown to be most appropriate in achieving effective impact sound insulation.

Different regeneration conduits braided from biodegradable material poly (glycolide-co-L-lactide) (PGLA) for peripheral nerve repair and their radial compressive properties are presented. The influences of the braided structure and braiding angle are discussed. The results have shown that the nerve conduit braided with the triaxial structure at 60 degrees of the braiding angle has a greater ability to resist radial compression.

The biodegradability of dispersants (naphthalenesulfonate formaldehyde condensates), used with disperse dyes, has been evaluated using different techniques such as chemical oxygen demand (COD), UV-spectroscopic analysis and tonometry. A biomass was used from industrial waste water which was acclimated for six months prior to use. The study has shown that biodegradation involves two steps: first, the cleavage of the CH2 bridges; second, the degradation of the aromatic nuclei. We identified a series of bacteria (Pseudomonas cepacia, Pseudomonas vesicularis, Pseudomonas stutzeri, Pseudomonas pichetti, Shevanella putrefacians, Agrobacterium radiobacter and Aeromonas hydrophila) that proved to biodegrade the dispersant very efficiently .